Report of the Atlantic Biological Station for 1951

Confidential

FISHERIES RESEARCH BOARD OF CANADA

REPORT

of the

ATLANTIC . BIOLOGICAL STATION

for

1951

A. W. H. NEEDLER, Director

With Investigators Summaries as Appendices

DEC 26 1951 1 /

`_d _firdrEfir OF fe---d

M. V. "Mallotus"

Built early in 1951 for the Atlantic Biological Station by VI. larren Robar, Upper LaHave, N.S., on plans developed by the Nova Scotia Department of Trade and Industry in co-operation with him and modified slightly for our purposes. Length overall 55.5 feet; beam 14.2 feet; gross tonnage 29.11; 106 h.p. Cummins diesel engine. Ordinary crew includes Captain, Engineer and cook-deck- hand with special observers frequently aboard. In 1951 the "Mâllotus" has been engaged in exploratory dragging in the upper Bay of Fundy and south-eastern Gulf of St. Lawrence, in scallop investigations and other minor work. The vessel is suitable for inshore work of many kinds, including dragging with various types of gear, long-lining, and general scientific and fishing operations. A varied program for 1952 includes participation in groundfish, herring, lobster and tuna- billfish investigations. REPORT FOR 1951 OF TEE 4 ATLANTIC BIOLOGICAL -STATION ST. ANDREWS N B By A. W. H. Needier, Ldrector

44 14 414 44 de * * 414 * 414 * * 044

' -- The general failure of other sources of animal pro- teins and fats to keep pace with the rapid growth of human ' populations is producing a world-wide intensification of use of the fishery resource.- In the waters off the Atlantic coast of" Canadafishing.is steadily Increasing not only by our own . fishermen but by those of other countries, some of them thou- sands of miles away. There is'every•reason to believe that this trend will continue both in our own inshore fisheries and in the international offshore fisheries; it will affect species as yet little used as well.as those already fished intensively. The problem of obtaining the best use of our resources can be solved intelligently only with the help of information which can be obtained neither easily nor quickly. It is the impor-' tant and interesting job of biological fisheries Investiga- tions, by. this and others of the Fisheries Research Board's -- Stations, to Obtain this information and pass it on - to the fishing industry and the administration. t e A few of our commercial species are very intensively . and the yield can be maintained at its most profitable . fished -level only by careful regulation; others are intermediate„._ '— perhaps fished intensively in some areas but not in others; . still other species, and apparently the majority, do not yet yield nearly as much as they could with more intensive or effective fishing. On the whole we must regard our fisheries as under-developed and, while regulating some and holding a ' watching brief on others, put emphasis on development rather . than on restriction. We must learn how to regulate intensive fisheries to the best advantage but must also help tà obtain better use of the resource by more positive means such as exploration for new stocks and improvement , of methods of find- ing and catching some species and of cultivating others. Our efforts in all these directions depend on bettering our * knowledge of how fish behave, survive, reproduce and grow in relationfto the conditions around - them. EM.1=112n0 The discovery of new stocks of fish, whether to extend well-eStablished fisheries or to develop new ones, depends to a high degree on better knowledge of the physical conditions in'our waters and how the various species react to them, and on the use of fishing methods new to us. This branch of our work suffers from the limitations inherent in any attempt to cover such a wide field with a very few boats and men. Exploration is, however, very important in the long run.and can sometimes yield fairly immediate benefits. Whether or not these are forthcoming we must improve - 2 - our knowledge of the fish stocks available to our industry if it is to have its full share of the long-term expansion which is taking place. Work in this field must continue and should be extended, both through hydrographie and general biological investigations and through exploratory fishing. Exploratory work in 1951 included, in addition to hydrographic investigations, a number of particular attempts to find new stocks reported in greater-detail below. Among them were continued search for , soft-shelled clams, scallops, shrimp, bait-worms and,flounders, more exploratory drift-netting for - high-quality summer herring, encouragement of the first commercial use of razor clams and some minor investigations on tuna. Improvement of-fishing methods. Most of the fish .' which we attempt to catch are out of sight and must be found and caught by a great variety of mechanical means developed - slowly over the centuries by trial and error. The development of fishing methods is - hindered by our ignorance of how the fish 'react.t6 them and, since our knowledge of the abundance and . movements of fish depends entirely on catching or seeing them, it is very important to thellsheries biologist as well as to the fisherman to improve fishing Methods and to understand more about how they work. Progress In this field is slow, being plagued by the infinite variety of gear, fish and circumstances and by the indirect and remote observation which is often the

• best we can do. It is, however, important for us to improve our knowledge of fishing gear - sometimes as a direct attempt to introduce a better method in our fisheries, and sometimes as a prerequisite for sound interpretation of our aen observations or of changing commercial catches. In 1951 the study of fishing methods has been an integral part of many of our investigations, including the development of "savings gear" for scallops, introduction of commercial Danish seining for'flatfish, further experiments with mid-water trawls for herring, exploratory drift-netting for herring; studies on the operation of small otter trawls, - and assessment of the-effects of hydraulic means of taking' soft-shelled clams. A proper attack on these problems needs the combined critical and open-minded attention of biologist and engineer, and the employment of an engineer, Mr. C. E. Petite, on the Station's staff is already bearing fruit. Regulation of intensive fisheries. A number of our fisheries are'highly intensive; in some areas, for example, two thirds or more of the lobsters of Marketable size are ' caught each year. In some of these cases it is believed possible for properly designed regulations to maintain the catch at a more profitable level than it would otherwise reach.' The fisheries administrations and public, especially on this 'continent, have shown an unaccountable willingness to , believe that restriction of fishing is necessary to preserve fisheries and that it can be made to increase the catch, and undesirable restrictions seem to have resulted in some cases. -j

Close study of intensive fisheries is necessary to determine 4 ■

-whether restriction would probably make them> more profitable - and, if so, what kind and degree of restriction is likely - to be - beneficial. A great deal of investigation Is needed in order.to give a sound opinion on these cases. Tut crudely, it is necessary to know what expectation there is of the fishery.having a second chance.to_catch and_keep any-fish- the „ restriction prevents - it from*using', and'whether the increased' : of the fish will.make -Up for the possibility that there *size will be no second chance. This requires knowledge of the.' growth, abundance, movements and survival of the fish and of

- the proportion caught by the fishery. . In 1951 investigatioàs of this kind were continued on ,the intensive and impbrtant lobster fishery and a number of -recommendations were made on its regulation. Periodic closure Of clam flats is emerging as a possibly beneficial:measure, though further study is required. Work was also continued on the smelt and scallop fisheries. We continue to hold a watch ing brief on the important groundfish fisheriés to recognize over-fishing should it occur and much effort is being spent on 'a study of the fishery and'thé - fish populations. A second

attempt to estimate the 'size of the harp seal population by • 'aerial,ph6tography confirmed the 1950 estimate of its order, - the increased take In. 1951 led to the view that.som9 Fe- but

- striction would be desirable, especially on the killing,of 'adult. seals. An increasing effort is being.madé to discover the complex background for regulation of the commercial and sports fisheries for Atlantic salmon. Increasing production bv positive cultural measures. Only in sheltered inshore waters and in fresh waters is it possible to improve*the conditions for reproduction, growth or survival enough to increase the production of valuable species of fish or shellfish. The measures used are often -cdmplex themselves and their success - is always affected by the many and very complex ways in which an animal -reacts to the conditions under which it lives. A great deal of investigationls, therefore, needed to develop the best cultural - procedures or "farming- methods", but the fact that these procedures and - their effects are more readily observed than in the cases of .fishing or fishery regulation in the deep sea, makes them :more easily:investigated by the scientist and understood by the layman, who also sees in them analogies with the more familiar agriculture. The Station'S work in thiS very varied field in7 eluded in 1951 continued experimental farming of oysters with its'associated_investigations, studies on the pond culture ot. trout and the use of predator control and fertilization to increase troUt production, study of the effects of predator

- control (both birds and eels) and of various planting procedures on Atlantic salmon production, continued observation of the effects of better access to spawning areas on the production of smelt and limited observation of the few - 4 - -remaining attempts at profitable clam farming. In all of these progress was made toward the development and assessment of cultural procedures. Imerovement of •ualit and handlin: methods. The assessment and improvement of the quality of shellfish from the public health point of view presents problems for the marine biologist and the Station has co-operated to a major and effective- degree in the public health supervision of the shellfish industries generally. Work continued in 1951 on the problem of making as full use as possitle of softshelled clams without danger to the 'public from paralytic shellfish poisoning, and investigations on the cleansing of sewage-contaminated clams have been commenced'and already show promise. Study of the physical factors influencing the survival of lobsters, and more direct holding experiments, were intensified in 1951 and offer good prospects for improvement of methods of holding live lobsters commercially both at the shore and inland. Investigation continued on the possibility of controlling the infestation of cod by round worms through reduction of the numbers of seals in which the worms mature. The results are not yet promising but the importance of the problem to the 'industry justifies continued work. Basie research. Attempts to solve problems directly concerned with better use of our fish resources constantly lead to other questions on which the solutions of the so-called practical problems depend. No line can be drawn between the practical and the theoretical, but in pursuing aims which are , primarily practical the crucial ramifications of the problems must be followed to their solution. Some may be solved by other research bodies, such as universities; many the fisheries biologist must solve himself, and it must not be forgotten that progress - towards the practical goals of the industry depends on a broad general knowledge of the kinds and conditions of life in the sea which can only be obtained by research at sea. Too close application to immediately practical problems and conse- quent neglect of broader or more basic research, whether at

- sea or in the laboratory, might well dry up the sources of . new ideas and facts which must be tapped for practical purposes. ,For these reasons the Station has striven to continue work of a basic and general nature in the face of strong and persistent pressure on all members of •its scientific staff for attention to immediate practical problems. It has co-operated with the Atlantic Oceanographic Group of the Joint Committee on Oceanography in hydrographie investigations designed to reveal the broad physical background for life in our waters. Its biological research has included such items as experiments on the reaction of lobsters to changes in their physical environment, study of the movements of bivalve larvae in response to • various factors, and investigation of many aspects of the-life - 5 - histories.of many species. The Station provided facilities for A A*

- scientists from other institutions working . on a variety of problems in.the general-field of marine biology. , - Application of results.. ,à1 great deal of effort on the part of the scientific staff has gone into maintenance of the close contacts with the administration and with industry which are necessary.if the results of research are to be used and if new work is to be directed along'useful lines. In addition to ! the co-operation with other bodies noted below, there has been frequent consultation with various branches ofthe Department_ on fishery regulation and development,.and numerous communica- • tions and discussions with representatives of the - industry. Such contacts are essential and in some aspects of the work need to . be strengthened; they - are also time-consuming and sometimes difficult to carry out without interruption of actual research or of the reporting of results through scientific publication. -= Co-operation with other bodies

• • International Commission for the Northwest Atlantic - Fisheries. In February, 1950, two North American and_eight European nations concluded a convention "for the investigation, protection and conservationof the fisheries of the Northwest Atlantic Ocean, in order to. make possible the maintenandeof a . maximum sustained catch for these fisheries". The resulting - Commission.held its first meeting In April, 1951, Canada, - Denmark, Iceland, - the United Kingdom and the. United States . having then.ratified the Convention. As the principal duty of

the Commission . is to .bring about international co-operation in • the investigation of the Northwest Atlantic fisheries and.to recommend joint action to the respective governments to regu-' late those fisheries to maintain maximum yield, and as it is .. the expressed policy of the Commission to fulfill.its purposee insofar as possible by co-ordinating research by the various.. . nations themselves, its work was from the start closely related to that of the Board's two biological stations on the Atlantic coast. The relationship was made even' closer at its first . meeting by (1) selecting the Station as its.temporary headquarters, (2) appointing Dr. W. R. Martin, on leave from the Station's staff for that purpose, as - its Acting Executive Secretary for one year from July 1, 1951, and (3) electing . the Director, already scientific adviser to the Canadian Commissioners, as.chairman of its Standing Committee on Research and Statistics. Mr. F. D. McCracken, Dr. G. F. M. Smith and the Director.took an active part in discussions with scientists of the U. S. Fish and Wildlife Service at Woods Hole in late April and at St. Andrews, September 15-17, at . which were formulated recommendations .of an experimental minimum mesh size for otter trawlers engaging in the haddock . fishery in the New England area and of a research program to follow its results. Prince Edward Island Fisheries Develo ment Committee. This Committee was appointed early in 1951, with representatives of the Dominion and Provincial governments, of the - 6 - fishermen and of the fishing industry under the chairmanship of the Chief Justice, to recommend to the two governments a program for development of the fisheries of the province. As representative of the Dominion government on the Committee, the Director enlisted the assistance of the Station in a consideration of its biological fisheries problems, and presented among other memo- randa a preliminary inventory of the province's fishery resour- cesl and recommendations on the regulation of the lobster fishery. Joint Committee on Oceanography. The Station continues to house the Atlantic Oceanographic Group and there is close co- operation with its activities, Dr. Lauzier of the Station's staff working with the Group and the Group undertaking hydrographic investigations planned to meet the Station's needs. Newfoundland Fisheries Research Station. There has again been close co-operation between the two Stations and mutual assistance in groundfish, seal and other investigations. Public Health. The close co-operation between the Department of National Health and Welfare, the Department of Fisheries and the Station deserves special mention. A co- ordinated attack on the problems of protecting public health with a minimum of interference with the commercial use of shellfish has been brought about through the Interdepartmental Shell- fish Committee and by continual close contact. The Committee, of «which the Director is chairman, Mr. Logie secretary and Dr. Medcof a very active member, is entering on its second decade of useful life. Its work has included discussion and planning of investigations and administrative policies concerning closure of polluted areas, self-purification of oysters and clams, closure of grounds when and where paralytic shellfish poisoning is a threat, and other matters important both to the public health and the shellfish industries. The considerable efforts along these lines have been well repaid. One of the important current projects is the development of procedures for the self- purification of clams, in which the Station, through Dr. Medcof, is co-operating with the Fish Inspection Laboratory. Co-ordinating Committee on Atlantic Salmon. This Federal-Provincial advisory committee, with representatives of the governments of the five Atlantic provinces and of the Federal government, was formed in 1949 to co-ordinate research, regulation and development activities of the various administrations for Atlantic salmon. The Station has co-operated closely with the Committee, the Director being chairman and

Dr. Kerswill secretary, and the findings of the Committee from • time to tim'e will have a strong influence on the research programs of both this and the Newfoundland Station. - 7 - progress of Investigations A brief summary of progress in some of the more important aspects of the Stations work is given below. More detail on any particular subject can be obtained by enquiry addressed to the Director, Atlantic Biological Station, St. Andrews, N. B. Lobsters

Regulation of the fishery. Major investigations were continued on the very valuable and intensive lobster fishery to answer the question 'That restrictions can be confidently expected to improve the yield?" The results point to minimum size limits as the most valuable measures for maintenance of the long- term yield at its maximum; size limits have the added advantage of protecting the fishery without the administrative difficulty or arbitrary nature of limiting catches or fishing effort. The latter measures are of more doubtful value, and seasonal closures, although sometimes justified on economic grounds, are believed to have little conservation value, a higher percentage of the stock being taken in the shorter than in the longer open seasons in our waters. The case for a size limit depends on the rate oP growth, the survival and the catching rate. Studies started in 1947 to determine the growth rate under natural conditions were continued in 1951 in three areas and are now concluded. Since 1947 over 27,000 lobsters have been marked with holes punched through the tail fan and liberated on the fishing grounds. The 2400 that have been recaptured show the annual growth to be relatively uniform over the size range studied, varying from 12.3% to 14.5% in total length and 44% to 52% in weight (Appendix 2). The high proportions caught annually (as much as three quarters in some • localities) have been shown by recaptures of over 75,000 lobsters tagged over the past seven years in several areas. The total mortality rate can now be estimated from extensive records on the numbers of lobsters of various sizes, combined with our new knowledge of the growth rate. It is apparent that the natural mortality rate is low under present conditions. Thus, with an annual growth in weight approaching 50%, a relatively good survival and a very high proportion caught each year, there is reason tofbelleve that it would pay in many areas to let lobsters grow to a larger size before catching them. A change of this kind, by increasing the numbers of lobsters on the grounds, might change survival and growth rates appreciably and other üilknown factors may enter the picture. Any change in size limit - must therefore be regarded as experimental to some degree and its effects followed closely. Since 1947 when the size limit at Fourchu, N. S 0 9 was raised from 7" to about 9" (total length).the catch of the valuable "market" lobsters (over 9") has continued to rise and in 1951 exceeded slightly the combined catch of "canners" (below 9") and "markets" before the change was -made,- the - landed - value - at 1951 prices would be increased by about one third (Appendix 1). - 8 - The size limit in those areas where it has been 3 118" carapace measure is now being increased in two annual steps to 3 1/4". Extensive carapace measurements showed that in the first year, when the limit is changed from 3 1/8" to 3 3/16", • the proportion of the catch affected will be on the average 11% by count and 8% by weight (Appendix 7). Continued population studies will indicate the eventual effects of the change in key areas. To evade minimum size limit regulations certain fishermen dismember live sub-legal lobsters and sell the separated claws and tails. This practice could be curtailed by a supplementary regulation establishing a minimum tail size. Measurements indicate that tail width is the most satisfactory measure of tail size (Appendix 8). Effects of environmental factors on lobsters. Better knowledge of the conditions under which lobsters will live is needed both to improve the handling of live lobsters and to understand natural changes in abundance. Experiments on the factors limiting the survival of lobsters were largely restricted in 1951 to a study of oxygen requirements. The oxygen concentration at which 50% of the lobsters died in 48 hours varied from 0.55 to 0,90 c.c 0 per litre, showing some relation to the temperature at which they had been acclimated. The data suggest that the concentration of dissolved carbon dioxide plays an Important part (Appendix 3) 0 Experimental lowering of salinity led to a decrease in blood concentration to almost the concentration of the external medium, but before this equilibrium was reached the blood concentration went much lower and rose again. Lobsters acclimated to 8° C. and tested at 8° C. can stand about 10A and corresponding internal salinity of about 12A but If tested at 25° C. the lower limit of both internal and external salinity is higher (Appendix 4, work by Dr. G. F. M. Smith and Miss M. Myers under National Research Council grant).' Commercial holding of live lobsters. An experiment concluded in December, 1950, showed that copper, monel metal, zinc and lead are toxic to lobsters in that order and that iron, aluminum and stainless steel are non-toxic (Appendix 5). During this experiment lobsters were held for more than seven months in stagnant but aerated water. Preliminary experiments in 1951 indicated that lobsters could be held commercially in stagnant artificial sea water supplied with compressed air bubbled through air stones (Appendix 6). These experiments will be continued in the hope that holding techniques can be developed to a point where they help inland marketing. Production survival and rowth of lobster larvae. Continued sampling of lobster larvae in Northumberland Strait has not shown great annual variation in abundance of first- stage larvae since 1949 since when collection techniques have been uniform, survival to the fourth stage (after three moults) was only 1% to 5%. It is planned to continue the sampling and to attempt to relate changes in abundance to their causes and to subsequent changes in £ ,Dundance of lobsters. Shrimps Exploratory trawling in 1947 to 1949 had failed to reveal commercial quantities of shriffip (Pandalus borealis); in 1951 further trawling at the place (off —CarIFF)-7nd the time (February and March) which the previous survey had indicated to . be most promising again failed to take commercial quantities. It now appears doubtful whether the inshore concentrations of large egg-bearing females, on «which the Maine fishery depends, will be found in our waters and it is planned to discontinue these explorations (Appendix 10). Oysters Oyster farming. Oyster investigations continued, in close co-operation with the oyster culture services of the Department of Fisheries, to assist the oyster farming industry with such routine services as prediction of settlement of spat and advice on the potentialities of areas proposed for development. Exploration of the prospects for oyster farming in the Richibucto area, N. B., in co-operation with the New Brunswick Department of Industry and Reconstruction revealed some promising areas for spat collection in the upper reaches of the Richibucto River and some good maturing grounds in the more seaward areas (Appendix 13). e - A general failure in production of spat for the second consecutive year will have adverse effects on commercial production and hindered our investigations designed to improve techniques of predicting settlement and of spat collection. An apparently normal spawning was followed by scarcity of larvae even in their early stages, indicating an early heavy mortality from unknown causes. Studies of vertical distribution of larvae and of larval abundance and resulting spatfall were continued using improved quantitative techniques. Prospects are emerging for improving prediction by determining the -minimum abundance of larvae at various stages which can be expected to produce worthwhile "sets" of spat (Appendix 16). Experimental control of barnacle sets, which - sometimes - conflict seriously with "sets" of Spat, was inconclusive because of scarcity of larvae (Appen- dix 15) and needs repetition in a more favourable season to confirm or dinrove the apparent efficacy of DDT dissolved in oil as shown by experiments in 1949. Further experiments have failed to reveal the definite superiority of the fixed, open, wire-bottomed trays used in Holland for rearing small oysters, over - the floating, - wooden- covered, wire-bottomed trays we have developed for that purpose. The need and search for inexpensive rearing techniques continues (Appendix 14). Progress In control of eel-grass is outlined later in this repor,r. Oyster diseas.:.3Q In 1914 a contagious disease of oysters was introduced tz ralpeque Bay, P. E. I,, and spread throughout the Malpeque-C2umpeque area in the next few years; it was carried to the Enmo:e-Percival area on the south coast - 10 - of the province in 1935 and to the Charlottetown inlets in 1935. In all affected areas high enough proportions of the oysters were killed to interrupt commercial production for a number of years. The present Malpeque stock, bred from the survivors of the disease, is resistant to it and for a number of years we have been comparing the survival of susceptible native and - resistant Malpeque oysters of the same ages held side by side in the Enmore and Charlottetown areas. A reconsideration of the data already at hand to show accumulated mortalities, including those occurring over winter, reveals that the course of the disease is characterized by heavy mortalities during the winter following the first open-water season of exposure. The data for the mortalities in oysters introduced into Malpeque Bay from 1947 to 1950 show a very similar pattern. The causative organism should be most profitably studied during the first season of exposure and the subsequent winter (Appendix 11). Histological examinations suggest that the recent serious mortalities of oysters from West River, Charlottetown, Pe Ee Ie, while held in storage are probably caused by a true disease due to an organism as yet unknown, and studies of West River oysters in situ indicate that it is not very contagious and that it does not develop the characteristic symptoms in the natural habitat. Examination of oysters held in cold air storage in Charlottetown and Montreal showed development of the symptoms to a maximum at the same time as in previous years. These examinations also showed that most of the affected oysters eventually recover a normal appearance and presumably throw off the disease while in hibernation in cold air storage. The symptoms appeared with the same timing regardless of the distance transported or the characteristics of the storage plant itself. It therefore follows that this condition is only aggravated by cold air storage and that oysters must be infected when taken from the rater even though they then show none of the symptoms of the disease and do not develop them if left there (Appendix 12)e Soft-shelled clams (Mya)

A review of the recent history of the soft-shelled clamlndustry of the Maritime Provinces (Appendix 17) shows that the annual take has risen In the last six years from 10,000,000 to 25,000,000 pounds, the marketed value passing well above the million-dollar mark and exceeding that of scallops or oysters. This production has been reached by rapid expansion to new areas stimulated by the great demand for shucked clams. Continuation of the exploration for unused clam stocks, which has been part of the Station's clam investigations for a number of years, failed in 1951 to discover any major producing areas, although areas were discovered in 1950 which have come into active production this year (Appendix 22). With no new areas to exploit and the known areas already subjected to very intensive digging 9 it may be expected that the yield will reach an equilibrium below its present level. The Station's efforts to develop profitable clam farming Included many years of careful experimentation on - 11 - methods of planting, growth and survival of various stocks - under various conditions of bottom, tidal level and crowding, control of enemies and damage by digging. Although clams can be grown, costs are too high, partly because of the very slow growth in our waters, and even the few remaining field tests on the most promising grounds are proving discouraging (Appendix 23). The future of this valuable industry depends, therefore, on using natural production to the best advantage and attention has been concentrated on problems of management for maximum continued yield. Earlier work had shown that digging causes considerable mortality among the clams which are left, and recent observations (Appendix 19) have shown that commercial diggers are able to take 60% of the marketable clams each time they dig an area over. As flats may be combed several times in a year, the annual proportion of the clams taken may be very high and the frequent digging at the same time causes serious mortality among those that are left. Experiments are now in progress in three areas with various types of soil to determine the effect of frequency of digging (semi-annual, annual, biennial or triennial) on the yield. The preliminary results which are now emerging indicate that the long-term yields of our clam flats could be increased by some'Scheme of rotational digging which would reduce the frequency with which they are now dug over. If confirmed,' these results can be very important to the clam industry (Appendix 18). Observations in 1951 indicated that "digging" clams with the water blast from the propellers of outboard motors, now illegal, is an efficient means of making use of clam stocks which are infrequently exposed by the tide and, if properly used, apparently causes less damage than the usual digging methods (Appendix 20). It offers a means of bringing additional' stocks into use and large-scale trials seem warranted. Recent investigations have shown that winter hounders (Pseudopleuronectes) cause serious reduction in the numbers of small clams, and rank with clam drills (Polinices) as important enemies (Appendix 21). Razor clams (quill Razor clams have been used commercially in New England for some years in clam chowders . and have come Into greater demand as supplies of soft-shelled clams dwindled. The discovery of large stocks at the head of St. Mary Bay, N. S 09 and encouragement of their usé by the Station led, in 1951, to their first commercial use in the Maritime Provinces with promising results. This species may become a valuable supplement to the supply of clams (Appendix 24) 0

222_1111=_PI_IDIAMftzL2DIaminated clams Dense stocks of clams in extensive polluted areas constitute a risk to public health through illegal sale and a- potential source of valuable supplies if they - can be made safe for himan Consumption. In 1951the Station cooperated -with the Fish Inspection Laboratory in a study of. purification methods. Preliminary results indicate that self-purification is - rapid when the clams are placed in clean water and it is hoped that a satisfactory procedure can be developed as has been done in the case of oysters (Appendix 25), • Paralytic shellfish poison The Station's major investigations in this field were concluded with the adoption a few years ago of policies which protect public health with a minimum of loss to the shellfish industry. Co-operation with the Departments of Fisheries and' National Health and Welfare has continued in the implementation of these policies and their extension to new areas. It was found in 1951 that whelks (Buccinum) which feed on toxic bivalves themselves become toxic - a fact of some importance in areas where whelks are considered a delicacy (Appendix 26). Bait worms Further brief exploration for "sand worms" (Nereis) and "blood worms" (Glycera) in 1951 revealed no commercial quantities of either species in eastern Prince Edward Island but blood worms were found in certain areas in western Nova Scotia In sufficient numbers for an inexperienced digger to gather in one low tide between Lkoo and 500 worms worth about $1050 per hundred. Trial shipments by air reached New York in good condition and it is hoped that this will lead to the establishment of a lucrative side-line to clam digging (Appendix 27). Scallops Forecasting trends in scallop production. Forecasts of general trends in the Digby scallop fishery.were seen as a possibility in 1948 when it was shown that the abundance of commercial-sized scallops regulates catches and that the abundance of young scallops born each year is determined to a large 'extent by hydrographic conditions at spawning time. That year the catches were low but it was predicted from what was known of hydrographie conditions in 1945 that there should be a recovery in catches under way by 1952. The reliability of this general method of prediction and of this particular prediction has been examined each year since then by measuring the catches of all sizes of scallops taken in series of standardized hauls made across the main beds in a three-day fishing program. The results indicate that the predicted recovery in abundance is under way and suggest that this method of prediction is reliable (Appendix 29). Examination of nine years' detailed records of scallop purchases, kindly made available by Mr. E. B. Richardson of.' 11iltaked1lSeaiProductS,- -Lt4support the conclusion, already reached from a study of Department of Fisheries statistics, that - 13 - year-to-year changes in catch are caused largely by changes in abundance of scallops; weather is mainly responsible for regular month-to-month variations within each season. The decline in abundance caused by the fishery as the season progresses also plays a small part in these but price changes seem to have little effect, if any (Appendix 29). Development of a "savings gear". Further progress has been made in the development of scallop drags which will reduce the catch of the sub-legal-sized scallops. Three types of modified mesh are being tested against the standard in a series of experimental hauls and it is planned to subject the most promising of these to commercial-scale trials later in the season. Preliminary results indicate that it effects a 50% reduction in the catch of sub-legal-sized scallops and a 10% increase in the catch of legal-sized. There seems to be good prospect of sub- stituting an effective minimum mesh for the size limit which cannot be enforced because scallops are shucked at sea (Appen- dix 30). Exploration for scalloug_in the Gulf of St. Lawrence area. This work was continued in 1951 for the third successive year. No new beds were discovered in the several areas explored but checks were made of the three beds discovered in 1949 and 1950. The heavy stock on the two-square-mile Richibucto bed has survived well and its scallops should be large enough to be worth fishing commercially in 1952. Another new bed was heavily exploited in 1950 and 1951 and is now "fished out". The third bed, although nearly obliterated by mass mortalities in 1949 and 1950 and by some fishing in early 1950, is showing signs of recovery but even if the young scallops now appearing survive they will not be of fishable size until 1954 (Appendix 31). Trials with small drags hauled by two-man lobster - boats and hoisted by lobster trap haulers showed that these can be operated profitably, making it possible to use the scallops when they are available without heavy capital expenditure which is hardly justified by the spasmodic production of the region. Groundfish The groundfish, including demersal species of the cod family andeflatfish, are the main material of the trade in fresh, frozen and salted fish. The groundfish fishery, though not as valuable inshore as lobsters, is by far the largest branch of the industry in the Maritime Provinces and even more important in Newfoundland. The rapidly increasing fishing effort by many nations on the grounds off our coast, and the ihipôrtance - Of this branch of the fishery to our economy, makes it imperative to watch closely the effects of fishing on the stocks and recognize and attempt to remedy over-fishing should it occur. On the other hand, the Canadian groundfish fishery is still under-developed and capable of expansion. Our investigations have, therefore 9 proceeded along tNo rather different lines - holding a watchini; brief to guard against either over- fishing or unnecessary restriction, and seeking improvement of our use of the resource. The fishery and the stocks. Especially since 1945 a great deal of effort has been spent on obtaining accurate and thorough information on when and where groundfish are caught and with what fishing effort, and in sampling the populations for age and size. The establishment of the International Commission for the Northwest Atlantic Fisheries (ICNAF) improves the prospect for obtaining similar information on the activities of all nations in the area and for putting it to use. As it is ICNAF policy to co-ordinate the work of the nations themselves rather than to set up a large organization itself, the Board's work in this field will have to be increased if ICNAF's needs are to be met. The value of work of this kind depends on collection of information over a long term so that changes in the fishery, the fish stocks and physical conditions can be correlated. Valuable results are, however, emerging already. Information being collected on the quantities of small fish discarded at sea (Appendix 34) is of direct importance to assessment of the value of minimum mesh sizes of otter trawls, now being considered by ICNAF. Prediction of changes in abundance is becoming possible, based on statistics of catch, catch per effort . and age and size composition of the catch (Appendix 33) 0 Methods of catching groundfish. The Station again co-operated in experiments in long-lining with "Cape Island" type boats in the Bonavista area, financed by the Department of Fisheries and supervised by the Newfoundland Biological Station. On the basis of the experimental Danish seining carried out by the M. V. "J. J. Cowie" in 1948 and 1949, commercial trials were arranged in 1951. Gear was loaned to a commercial fisherman operating a 39-foot boat in Chedabucto Bay, N. S., and his outstanding success shows that in that area Danish seining was more efficient than small otter-trawling in catching flatfish (Appendix 35) 0 The method needs such smooth bottom that suitable areas are restricted; they have not, however, been fully explored. Development of flounder dragging. Exploration in 1949 led to the development of commercial flounder dragging In that area; further exploratory dragging at the head of the Bay of Fundy in 1951 failed to extend the present grounds (Appendix 36). Exploration in the south-eastern Gulf of St. Lawrence, using the 55-foot M. V. "Mallotus", yielded good catches of hake, haddock and witch from East Point to Prim Point, P. E. I, in depths of 15 to 21 fathoms (Appendix 37) 0 Special records of catch, fishing effort and age and size composition of catch, together with tagging to measure movements and fishing Intensity, indicate that the inshore dragging for flounders in the Bay of Fundy, which resulted from our explorations from 1947 to 1949, can be expanded -l5 - substantially only by the discovery of new grounds (Appendix 38). The :Landings of flounders could be increased and extended to new areas if the industry would handle somewhat smaller sizes, as it does in New England. Parasites. Efforts have been continued to discover the complete life history of the "cod-worm" (Porrocaecum) and to carry out experimental control through reduction of seals in the Bras d'Or Lakes, N. S. (Appendix 40, see also below under Seals). Investigation of the life history and incidence of a trematode which encysts in flounders and affects the quality of flounder fillets was continued (Appendix 39). Herring Most parts of the herring stocks on our Atlantic coast are very lightly fished and could support a much larger industry. Except for the small herring or "sardine" industry of the lower Bay of Fundy and the winter fishery for larger herring in certain Newfoundland areas, our catches are made during short seasons and consist mainly of thin spawning fish. Improved catching methods, by extending the season and catching fatter herring, might well lead to a much greater use of herring whether for meal and oil or for high quality food., The Station has continued on a reduced scale the exploratory fishing and population studies initiated by the Atlantic Herring Investiga- tion Committee. Exploratory fishing. Exploratory drift-netting in the Gulf of St. Lawrence in 1951 did not yield such good catches as in 1950 but this is apparently attributable to deficiencies in gear and inadequate knowledge of herring movements. Improved gear is already being obtained for 1952 and it is planned to concentrate efforts in a few promising areas so that the verti- • cal distribution of herring in relation to temperature, food and light can be studied more effectively _(Appendix 41). Fat- ness of the drift-net herring was again followed, indicating the very rapid recovery from the poor condition during spawn- - ing (Appendix 44). A further trial of the pelagic, two-boat Larsen trawl by two well-matched commercial boats using our nets demonstrated the abilityfof the gear to catch large quantities of herring but confirmed its inability to stand heavy strains. Further e±periments are planned with a net of heavier twine, and also with a smaller net in the St. Andrews area in the coming winter (Appendix 42). Herring year classes and populations. Further sampling In 1951 confirmed the presence of a number of more or less distinct herring popu7at1ons. A striking feature is the large number of year classes represented in most areas, indicating a low total mortality rate and, consequently, the low level of exploitation (Appendix 43). - 16 - Tuna (Thunnus thynnus) In 1951 the failure of the smaller "jumper" tuna (40 to 125 lb.) to appear cut the Nova Scotian production in half and prevented further trials of trolling and other fishing methods. The "jumpers" have been found to be principally in their fourth to seventh years; age estimations of the large tuna cannot be made from their scales and other methods are being tried (Appendix 47). Mr. Day, who carries out the Station's tuna investigations, attended a conference at the Bermuda Biological Station in May at which a number of aspects of the potentialities of oceanic fisheries were discussed and some plans made for co- operation in a study of tuna migrations. Smelt The smelt investigations have a general as well as a particular significance because of the similarity of the problems to those of maintaining or improving the fishery for other anadromous species. Benefits to the large Miramichi fishery are sought through improvement of conditions for reproduction and regulation of the fishery. Spawning, larval production and the commercial catch. Earlier investigations have shown that crowding on spawning grounds can be reduced by the removal, at little cost, of obstructions in the spawning brooks and that this leads to increased production of larvae; work along these lines is being continued (Appendix 48). Estimation of the sizes of spawning runs, visually and by fishing, and systematic collection of larvae show that the volume of larval production depends more on other conditions than on the numbers of spawners (Appendix 49). Some of these conditions are beyond control but the value of increasing the number of larvae by such methods as clearance of spawning brooks is being assessed by observing the relationship between changes in the abundances of larvae and changes in the contribution of the same year classes to the fishery. Relative numbers of larvae from 1948 to 1951 were approximately 2:5:11:2. Smelt contribute to the fishery principally as.they approach 2, 3 and 4 years of age and the contributions of the 1948 and 1949 year classes are only partially evident, although with some indication that the 1949 year class will make the larger contribution. Granted normal weather, an increased catch is predicted this 'winter on the basis of year class strengths as they enter the fishery (Appendix 50). • The rate of growth in different year classes varies . enough to affect the agas at which they make their principal contribution to the fishery and, consequently to influence the size of the catch in any one year (Appendix 52). Early-srowning and late-spawning Populations. Further analysis of vertebral counts confirms the earlier conclusion that early- and late-spawning smelt are different and tend to -17- reproduce smelt of similar habit. Whether.or not this is an inherited tendency or the result of an environmental mechanism it has a bearing on the future regulation of a fishery which depends almost entirely on early spawners (Appendix 51). Trout The Station's trout Investigations attempt (1) to evaluate trout production in a variety of fresh waters and the environmental conditions associated rith various levels of production in order to discover what natural deficiencies are limiting it, (2) to develop procedures to overcome these deficiencies and thereby improve production, and (3) to acquire knowledge of the life histories of brook trout and associated species as a background for these developments. Fertilization of natural lakes. From a study of trout production and associated limnological conditions in eight Charlotte County lakes it was concluded that a poor supply of nutrient salts was primarily responsible for a low production of trout. Commercial inorganic fertilizers were added to Crecy Lake (50 acres) in 1946 and, in half the quantity per unit volume of water, to Gibson Lake (59 acres) in 1947 in an attempt to increase organic growths and specifically trout production in an economical and worthwhile manner. In Crecylake the growth rate of introduced trout was decidedly improved, especially in the case of fingerlings which by the spring following planting were for the first time sufficiently large to enter the anglers' catches, which consequently increased. A similar result did not obtain, however, in Gibson Lake. Thus the procedure met only with partial success, but gave promise of being worthwhile under certain conditions and both lakes were fertilized for the second time in 1951 with comparable amounts of nutrient materials (Appendix 57) 0 Predator control. The fertilization of Crecy Lake in 1946 resulted in a definitely better growth rate of the trout during the season following the addition of the nutrient materials. A comparable growth rate continued during the next two years but the survival of planted trout to the anglers' catches declined. Concurrently it was noted that fish-eating birds and mammals were attracted to the lake in greater numbers by a consistent annual stocking which provided a greater population of trout in Crecy than in neighbouring lakes. Attempts to control these fish-eaters were initiated in 1949. In 1950, and on an increased scale in 1951, the survival.of planted trout to anglers' catches ras much improved, but with the greater survival the growth rate fell and prompted a second fertilization in 1951 (Appendix 57) 0 Control of predators at Crecy Lake was extended in 1950 to the trapping of eels, which are the only serious fish competitors and predators of trout in the lake. A reduction In their number probably contributed to the greater survival of planted trout in 1951 than in 1950. Best control , - - 18 - involves the barring of the young, or elvers, from entering the lake. In 1951 a dam was built in the outlet just below the lake and appeared to be effective when made entirely water-tight except for the spill-way, although the proof will necessarily await observations to determine if the eel population in the lake becomes depleted in the future. Our results to date point to predator control in the fashion practised at Crecy Lake as a worthwhile procedure for betterment of trout angling. Its potentialities will probably be best realized in conjunction with fertilization to provide for improved- grawth of trout as predator control in non-productive waters would prove of doubtful value. At Crecy Lake it has required the attention of a field man on the lake throughout the year. The procedure is applicable only to waters that are small enough for proper supervision. General application would be limited by costs. Trout production in artificial ponds. The streams of Prince Edward Island, in contrast to the waters of the Maritime Province mainland in general, are highly productive of young trout because they offer very favourable environments for trout reproduction, survival and growth at early ages. However, they are generally small and there is a natural deficiency in bodies of water sufficiently large to harbour trout in abundance to angling size and make them readily available to the anglers. Mill ponds on Prince Edward Island streams have demonstrated their worth as fishing areas. A creel census at a 23-acre pond on the Montague River has shown that the anglers° annual take has varied between 22 0 4 and 440o pounds per acre over the last nine years, and that, notwithstanding the variations from year to year, there has been no evidence of over-fishing (Appendix 53). Pond formation is therefore indicated as one method for improvement of the trout angling and studies are in progress in three experimental ponds to determine their maximum carrying capacity for trout. The current investigations are concerned with the determination of the suitable density of stock for optimum production of trout.of angling size under natural conditions in these ponds. It is planned to investigate later the possibility of improving production by supplementary feeding and by fertilization of the waters. With an initial density of 400 marked yearling trout per acre, yields (final total weight of the market trout less initial total weight) as high as 29 pounds per acre have been realized over a summer period of about 2-1- months. However, the results have shown extensive variations which cannot be wholly ascribed to differences between ponds or seasons but may in part be accounted for by predation and by difficulty in controlling access of native stock Into the ponds from the tributary streams during spates. The physical difficulties of operating the ponds to give desired control of stock may necessitate revision of the program. Nevertheless, the results to date demonstrate that such artificial ponds are capable of producing more trout flesh than is generally appreciated (Appendix 54). Population and movements of trout in a Prince Edward Island stream. A study of the Prince Edward Island trout -19- fishery must consider not only the trout in the streams and ponds but also that part of the population that runs to sea and periodically returns to fresh water. Pond formation restricts the movements of the searrun trout into the streams, and affects their availability to the anglers and the areas accessible to them for spawning. An investigation was begun in 1946 at Ellerslie Brook to assess the effects of pond formation upon the trout population of a stream system, to study the relationship between the sea-run and brook populations, and to gain Information on the value of a fish-way as a means of overcoming restrictions imposed by dams. Trout have been captured, enumerated, measured and tagged throughout each year in a two- way fish trap situated near the head of tide. A creel.census is kept of the trout angled in the brook and estuary. In 1950 a second two-way trap was installed just above the proposed pond site to provide data upon the movements of trout within the stream and between stream and pond when the latter is formed in 1952. Assessments are also made of the summer populations in the stream, of special interest being the fish of the year which are not captured in the traps (Appendices 55 and 56). The annual count of trout moving both ways through traps at the head of tide has varied roughly from 3,000 to 5,000. These counts include duplicate records of individuals that moved more than once through the traps in the course l e a year, but they suffice to illustrate that a large number of trout are involved in the movements into and out of a small Prince Edward Island stream that has an effective length for trout production of only about 7,500 yards. Most of the trout involved are young; approximately 80% are in their third year of life. The catch by anglers during the last five years is between 1,000 and 2,000 individuals, taken at rates from 1.5 to 2.1 per rod-hour. The brook also supports a population of young salmon and in the spring of 1951, 585 smolts ran from the stream. Progeny from sea-run and brook stocks of trout were planted in Ellerslie Brook as fingerlings in 1948 and as yearlings in 1949, after being marked differently by fin-clipping, to learn if either of these groups exhibited a greater tendency than the other to run to salt water. A considerably greater number of the sea-run stock have gone to sea, but the picture is obscured by a size differential which may have an appreciable effect upon the movemehts and upon the number taken by anglers before going to salt water. It can be stated that the progeny from both groups will run to sea, with a possible greater tendency on the part of those from séa-run parents. A reduction by dams of areas available to the sea-run group for spawning may not be serious since this group can apparently be derived from populations of young trout in the stream irrespec- ttie of parentage. Electrical fishing Further field tests of electrical fishing, July 18 to 29, by a team of five scientists and two mechanics confirmed -20 - its value in small streams of water having moderate or low resistance and its limitations in deep, fast or resistant waters; its value must be assessed for each research project (Appendix 58). Experiments, with the co-operation of the Fish Cul- ture Development Service, showed that electric fishing can be seriously damaging to salmon eggs in various stages of development (Appendix 65). Salmon Atlantic salmon have a moderate commercial value and a great importance to anglers and the tourist industry. The Station's investigations have recently been concerned chiefly with attempts to increase production of the young in fresh water, especially through control of predators and the planting of hatchery-reared fingerlings. They are now being extended to include study of a large salmon river and its contribution to the fisheries.

Control of enemies as a means of increasing smolt *production. The year 1951 marked the practical termination of the experiment in the Pollett River, N. B., comparing production when mergansers and kingfishers were under control throughout the year against production when no such protection was afforded. On the average, smolt production with such protection was about eight times better than without, and the poorest yield with protection was three times better than the best without. These increases apply to a situation where protection was applied throughout the year (Appendix 59) 0 Predation by mergansers has been indicated as the chief factor limiting production of young salmon in several Maritime streams. Merganser habits, life histories and distribution are being intensively studied. The findings suggest that the limiting effect of merganser predations applies to nearly all important Maritime salmon streams (Appendix 63). Studies are in progress to discover what effect eels, as competitors or predators, have on the production of young ialmon, and include'observations on their natural history in salmon waters, experiments on the feasibility and effects of their removal and experimental study of their behaviour (Appen- dices 64 and 65). How densel should salmon be planted? Further results of experiments on the effects of degree of dispersal In planting salmon fingerlings indicate that within wide limits it has no important effect on smolt production. The productive capacity of an 11-mile section of the Pollett River is being studied by comparing the results from very heavy and very light plantings (using a constant degree of dispersal) with the production (already measured) from 250,000 salmon underyearlings. These results should indicate both the best survival rates froM hatchery stock and the highest production which can be expected from the stream. Thereafter comparisons will be made with reproduction by natural spawning, to determine capacity, and number of spawners needed for best production (Appendix 60). Measuring production of young salmon.- Evalùationof .fish crops is a most important aspect of studies on production. The counting of all descending smolts is a direct approach to this problem and is used in some salmon studies. Weirs which cut off an entire stream, however, are subject to hazards arising from weather conditions and industrial operations; those which do not are less liable to these hazards, so a method for estimating smolt runs through use of partial weirs is being developed (Appendix 62). Information on standing crops of young salmon and other species within a stream is useful for determining limiting factors at stages intermediate between seeding and smolt descent. For this purpose seining within small sample areas have been used. The reliability of total counts is subject to variables which cannot be measured, whereas estimation based on recapture of marked fish are less subject to such variables and are being developed further. With the accumulation qf e successive years , data, prediction of smolt production based on estimation of parr populations is being attempted (Appen- dix 62). Salmon production of the Miramichi. Continuation of the program started in 1951 9 to estimate total production of smolts, discover their contribution to various commercial fisheries and study the biology'of the salmon in this river system generally involved the operation of counting fences on . two major branches (Appendices 67 and 68). About 49,000 were marked; 48 of these were found among 19 671 smolts caught in the estuary (Appendix 69) suggesting a total production of over a million and a half smolts. A search will be made for the marked fish in both commercial and sports fisheries. Times and sizes of salmon runs were recorded and variations will be related to physical conditions and to parr and smolteproduction. Removal of mergansers from one branch, started in 1950, was continued and assessments of abundance of parr by seining indicated that its smolt production is likely to be doubled (Appendix 66). Cod-worms and Seals The cod-worms, which are perhaps the main obstacle to the use of cod fillet3 in the expanding markets for fresh and frozen fish, have been shown to be the immature stage of a worm which matures in scls. The two species of seals resident in Maritime Province waters - harbour and gray seals - are being studied to improve our knowledge of the need for and means of reducing their numbers in the hope that the cod-worms can in that way be reduced to harmless levels. In the Bras d'Or Lakes a study of cod-worms and Èeals is in progress in preparation for an experimental attempt to reduce the numbers of seals in that area. If ways can be found of doing this the results will indicate the prospect for improving the - eality of cod- in respect of cod-worms by a general reduc= tion of seals. The prospects for success are none too good but the stakes are high enough to justify the effort. Food of seals and incidence of cod-worms. This year, as last, a considerable variety in food items was found in harbour seal stomachs, with a concentration on herring, squid and flounders (Appendix 70). Incidence of cod-worms in seal stomachs continues to support the evidence of previous years that harbour and gray seals are major vectors of this parasite, and that harp seals during the southward migration from the Arctic, the whelping season on the ice and the entire sojourn in waters east of Newfoundland are involved to an insignificant extent. Harp seal stomachs from the Magdalen Islands in April and May, however, contained cod-worms, many of them mature, and this may render reduction of the worms in Gulf of St. Lawrence cod difficult, since about 300,000 adult harp seals visit the Gulf although they feed only for short periods (Appendix 71).

Effects of the bounty on harbour seals. Analysis of • harbour seal bounty returns over the past two and a half years shows that the annual kill of this species has substantially increased since 1949, when jaws were required in support of bounty claims in order to prevent the payment of claims on other species. Raising the bounty on seals older than one year to $10.00 in the summer of 1950, leaving pup bounties at $5.00, has raised the percentage of this older group in the kill, with Indications that it will almost be doubled. Maturing and breeding seals, which are the cod-worm vectors and which do the damage to nets and fish in them, are thus being killed off at a greater rate, which should result in the desired over-all reduction in the population. For such general reduction the bounty system as now organized appears to be the best method. It has a widespread coverage, fraudulent submission of claims is . negligible, and it makes use of the best hunters with local knowledge of their areas who otherwise would not be available for control work. Detailed age studies of the bounty kill will be carried out through sectioning of canine teeth from the jaws which are forwarded to this Station, and the effects of the bounty control and of other local measures will be followed closely (Appendix 72). Attempted experimental control in the Bras d'Or Lakes. During the past autumn and winter an investigation of the occurrence of seals in the Bras d'Or Lakes, N. S., was begun to prepare for an attempt to reduce the seal population there and discover the effect on the incidence of cod-worms in the localized cod populations. Harbour and gray seals, several hundred in number, occur in the lakes only during the late autumn and winter mnths. Movement into the lakes begins in November, and up to Ch.2-istmas the dominant species is the gray seal. After Christmas the harbour seal appears to be the most common species and the adult female grays apparently leave the lakes to pup on the outside coastline early in February. The most successful seal hunter in the Maritimes managed to kill only 22 seals (11 grays and 11 harbours) during open water. Local interest in hunting for the bounty, even when augmented by a substantial additional reward, could not be aroused, Hunting experiments on the winter ice, when the seals congregate in open leads, was planned but the lakes failed to freeze over for the first time in 50 years. Further control efforts and study are planned in the winter of 1951-52 (Appendix 73). Status of the gray seal., Our recent investigations have revealed the status of this species, believed by some to have been approaching extinction (Appendix 74) 0 It is now known that there are whelping groups on Deadman Island in the Gulf of St. Lawrence, in Northumberland Strait, on Miquelon Island, along the north-east Cape Breton coast, on Sable Island, on the north-east coast of Nova Scotia near Marie Joseph, and around Grand Nanan Island. There is a seasonal movement in the spring into the Miramichi estuary, where the seals stay until early winter, and another into the Bras d'Or Lakes. In these two areas the gray is an important vector of cod-worms and local 1----__control measures are being undertaken. The gray seal on this coast pups in February instead of in September as in the British Isles, and it is possible that it represents an undescribed species. Field work in the Miramichi estuary was commenced in 1951 in an attempt to discover some means of reducing the population there (Appendix 74). Harp seals Investigations to lay the basis for maintenance of the valuable harp seal fishery at its maximum long-term level were intensified in 1951. A general picture of the life history and migrations is emerging and informationhas been obtained which raises important questions of the need for international regulation of the increasing take (Appendix 76). The apparently distinct breeding populations in the Gulf of St. Lawrence and east of Newfoundland (the "Front") both spend the summers in the Arctic, move southward in the autumn and early winter as far as eastern Nova Scotia, return northward in February to have their pups on the ice in the Gulf or off southern Labrador, mate and drift southward with the ice, only to migrate north in May and June. Pups marked in the Gulf in March have been recovered in Greenland and further tagging is planned to discover how distinct the two populations really are and to learn more of their movements (Appendix 78), Females first mate at the end of their third year, as shown by pregnancy scars and corpora lutea, combined with age estimation from annual rings in canine teeth, and males when they are two or three years older. The immature seals take part in the migrations congregating by themselves somewhat later than the whelping "patches". The age composition of seals, mature and immature, netted at the Strait of Belle Isle during the southward migration, indicates a total annual mortality of about 20% after maturity, and observations in the White Sea show a natural mortality of 20% from 1 year to 2 and 12e from 2 to 3; natural mortality from birth to 1 year of age is probably higher than 20%. Aerial photography in 1950 and 1951, in spite of difficult weather conditions, showed a certain consistency and yielded an estimate of the annual production of. pups on the . Front of the order of 430 1 000 and in the Gulf of half this number. In the catches by nets before the breeding season the sexes are about equal in numbers and the immature seals ("bedlamers", a corruption of bête de la mer) about equal to the mature. On this basis we may estimate on the Front about 430,000 pups, 860,000 immature and 860,000 adults, and about half these numbers in the Gulf. In 1951 the combined Canadian and Norwegian kill on the Front was about 340,000, about double that in 1950, and of these about 250,000 were pups and the rest older. This leaves a pup "escapement" of only 180,000 which must suffer one year of natural mortality and two years of natural mortality plus killing as bedlamers before entering the breeding population. To maintain the herd it must replace -the kill of 90,000 adults and bedlamers as well as the natural mortality of these groups (itself about 180,000 on a 10% basis). Although the population estimates can claim no high degree of accuracy they suggest strongly that the present kill could not be maintained. On the above basis it takes more than two pups to produce a breeding seal and each pup Is itself considerably more valuable to the industry. It has therefore been recommended that restrictions should be placed first on the killing of adults and discussions are under way attempting to find measures acceptable to both the Canadian and Norwegian industries and perhaps leading eventually to international agreement. Control of eel-grass on mister grounds Investigations on the biology and control of eel- grass were continued in 1951. Symptoms of the disease which decimated eel-grass in the early thirties are still present but the plants seem to be in normal health. Experimental results in 1951 confirmed the view that oysters on the bottom in eel-grass do not grow as well as those clear of it. Control methods employing various means of covering the eel-grass infested bottom continued effective wherever the coverage was complete to start with. Several of these areas have now passed through three full years since treated. In some cases where sand or gravel has been used a few seedlings have become established.

Cutting as an Immediate but temporary control method was practised again in co-operation with certain oyster farmers. - 25 - The plots treated in 1950 with high concentrations of Benoclor (0.43 qt. per 100 sq. ft.)„elther 3 or 3C„ in spray form remained clear of eel-grass as did those treated using sand as a means of spreading the chemical in concentrations as low as 1 gallon per 1000 square feet. Attempts to dilute Benoclor with engine oil in order to cut down the expense of the treatment proved unsuccessful. Results of a large-scale tréatment using Benoclor on sand were generally disap -pointing but were of value in that they showed that areas where a strong current occurs cannot be successfully treated with the concentrations effective elsewhere. Irish moss The Station co-operated with the Department in its efforts to improve the quality of semi-processed Irish moss by examining the raw material and the product in western Nova Scotia to discover what standards of quality are desirable. Develo Much of the work on the development of fishing gear has been mentioned in connection with the various investigations outlined above. A number of other projects are in progress, including tests of the value of a "tickler chain" in flounder dragging (Appendix 82). The Station's work in this general field is still in an early stage of development. The Station is co-operating with the National Research Council in its efforts to develop a small diesel engine suitable for fishing boats and assisted Messrs. Kuhring and Golitzine, in charge of this - work, to arrange contacts vith the industry. Reference collection • The development of the Station's reference collection proceeded slowly in 1951 with the help of only casual and volunteer assistance. New or unusual records of occurrence In 1951 a number of new or unusual fish and invertebrates weré recorded in the Maritime Provinces, most of them pelagic southern species associated with high temperatures (Appendix 81). Hvdrography The hydrographie investigations of the Atlantic Oceanographic Group, with headquarters at the Station (Appen- dices 83, 83-A to 83-M) are of basic importance to the Station's work in fisheries biology, and the close co-operation between the Station and the Group has continued. Perhaps of greatest long-term importance is the program of regular recording of representative hydrographic -26- observations over a long period. This program, developed by consultation between the Station and the Group, is now well under way. Our understanding of changes in abundance and movements of marine organisms, Including the fish and shellfish which are our main interest, depends on knowledge of the hydro-, graphic conditions and their changes. The possibility of discovering causal relationships increases as information becomes available over a longer period. Eventually we hope for prediction of these changes. Activities associated with development of the general oceanographic picture and basic principles included study of ' the chemical effects of ice formation in sea water (83-C), study of currents and associated conditions in Grand Manan Channel (83-I and J), study of the mechanism of water replacements on the Scotian Shelf (83-M) and of the flushing of estuaries and accumulation of varied records for later study (83-K and L). Results of a survey of conditions in the Strait of Belle Isle in 1923 are now being prepared for publication in co-operation with Dr. Huntsman who was in charge of the work (83-E). Changes in salinity in the surface waters of the southern Gulf of St. Lawrence have been related to run-off (83-A). Unusually high temperatures prevailed on the Scotian Shelf in 1950 and 1951 (83-D) and were accompanied by unusual distributions of fish which disturbed traditional fishing for groundfish. Surface water temperatures at the Station have shown a fairly definite upward trend for the past ten years, with temperatures in 1951 the highest in thirty years' records; this is associated with the appearance of warm-water Species (Appendix 82). A comparison of cumulated temperatures in the Gulf of St. Lawrence and Bay of Fundy was initiated in connection with studies of growth of lobsters (83-F), and study of conditions in the north end of Northumberland Strait with study of abundance of lobster larvae (83-G) 0 Special hydrographic work was commenced in the Miramichi estuary in association with salmon investigations (83-H). Use of Station by other scientists Facilities were again given to Miss Constance MacFarlane of the Nova Scotia Research Foundation for studies on the life-histories of seaweeds, and to Dr. Vibeke Englebert of the University of Toronto (assisted by Miss Mary E. Needler) for cbmparative cytological work on the blood of marine invertebrates. Dr. G. F. M. Smith (assisted by Miss Marjorie Myers) investigated changes in lobster blood .in reaction to changing salinity under a Natfonal Research Council grant. Such contacts are very valuable and stimulating. Dr. Huntsman again made his summer headquarters here; his presence is always welcomed because of his long experience in the field and his unusually great critical abilities and originality. - 27 - Visitors The many visitors to the Station included Dr. R. V. Truitt, Director of the Chesapeake Biological Laboratory, Dr. J. W. Burger of the Mount Desert Biological Laboratory, Dr. Birger Rasmussen of the Norwegian Directorate of Fisheries, Dr , D. L. Belding and Mr. H. J. Turner of the Woods Hole Oceanographic Institution, Dr. H. W. Curran of Queens Uni- versity, Mr. E. M. Gorman, Director of Fisheries for Prince Edward Island, Dr. Martin W. Johnson of the Scripps Institute of Oceanography, Dr. H. I. Battle of the University of Western Ontario, Mr. M. Oppedal, fisheries attache to the Norwegian Embassy, Washington, Dr. W. F. Hampton and Mr. P. P. Pratt of the Birds Eye Division of General Foods, Mr. Colin Storey, Director of Fisheries Engineering and Development and Mr. R. A. Harvey, Director of Vessel Construction and Inspection of Newfoundland. Mr. W. J. M. Menzies and Mr. Percy Nobbs visited the Station and some of its field investigations in connection with the former's review of the Canadian situation for the Atlantic Salmon Association. Dr. L. A. Walford, Mr. E. H. Dahlgren, Dr. Herbert Graham and Messrs. Homard Shuck, John Clark and Theodore Widrig, 'all of the United States Fish and Wildlife Service, visited the Station in connection with recommendations on minimum otter-trawl meshes to Panel 5 of ICNAF. Hon.Mr, Justice Thane A. Campbell, Chairman of the Prince, Edward Island Fisheries Development Committee„visited the Station in August. Frequent visits by fisheries investigators from New England continued, including this year Mr. Dana Wallace, Mr. Philip Groggins and Mr. L. W. Scattergood. Drs. D. R. Gascoyne and C. E. Atkinson and Messrs. Wm. Hagen and Jas. Mason, all of the U. S. Fish and Wildlife Service, and Mr. Jas. Fletcher of the Maine Game and Inland Fisheries Commission, visited the Station in August to discuss plans for salmon research in Maine. The President, Mr. Francis Millerd„ Honorary President, F. W. • Wallace, and Manager Gordon O'Brien of the Fisheries Council of Canada visited the Station during a five-peek tour of Eastern Canada. Last, but not least, there mere visits by a number of members of the fishing industry in the Maritime Provinces and Newfoundland, as well as a great many other members of the Federal fisheries service. Personnel and Ormnization The personnel of the Station to December 1 and organization as of September 1 are presented in the appended state- ments. There were no important additions to the staff and the limitation of the total number led to the employment of 12 seasonal scientists as compared with 24 in 1950 - an important loss. Dr. C. J. K,ceswill was seconded to Headquarters throughout the year, t- lthough able to give some supervision to salmon investigations. Dr. W. R. Martin went on leave of absence on July 1 as Acting Executive Secretary of ICNAF, leaving the groundfish investigations seriously poorer in senior scientific personnel. - 28 -

Buildings During the year plans for the fire-proof extension of the present main building were completed. In preparation for its construction a roadway ras built along the north side of the main building, as well as a retaining wall, with associated fill, along the seaward side of the proposed site, these improvements are valuable in themselves° Conditions at the Station remain seriously crowded, giving only about half of the space per person now accepted as best, and subject to considerable fire risk. A fire-proof record storage of concrete and steel construction attached to the largest frame building, formerly a residence and now used for working space, was nearing completion as the year 1951 closed. Boats The boats operated by the Station included the 65- foot "j. J. Cowie", the 55-foot "Mallotus"„ the 46-foot "Gulf Explorer" and the 39-foot "Pandalus", all diesel-powered and equipped for a variety of fishing operations. All of these except the new "Mallotus" are described in greater detail in the 1950 report and the "Mallotus" is described in the frontis- piece of this. Small gasoline boats are also operated at St. Andrews (the "Clupea H.") and at Ellerslie (the "Ardea"). Many aspects of the work are seriously hampered by the small size of all the Station's boats which limits the places and conditions in which they can do satisfactory work, as well as the actual operations which are possible. Information and Education Individual contacts and correspondence remain the principal means of bringing our results to those in the administration of the industry who use them. , Publications, a list of which Is attached, show some Increase over 1950 and the volume of material in preparation is much greater. Manuscript Reports are also listed and the distribution of material in this regular Board series is proceeding steadily. The Annual Report with Appendices remains the most complete and up-to-date summary of the Station's 'work. The Station did not assist in the preparation of any motion pictures during the year. A single radio interview was recorded by Mr. Saunders over CFCY on the trout work at Ellerslie Brook. No recordings have been made for the re- organized CBC Fisherman's Broadcast although some are planned early in 1952. This-year the Department of Fisheries display at the Lunenburg Exhibition, in which the Station has assisted in the past, was prepared entirely by the Information Services. The Station did, however, again prepare and supervise a display at the Shediac Lobster Festival. Five feature articles were - 29 - contributed to "Trade News". Co-operation with the Information Services included some provision of material and advice on articles prepared by their own writers; it is hoped that they can make regular visits to the Station for this purpose. Dr. Wilder addressed the annual meeting of the United Maritime Fishermen on the problems of lobster regulation. A number of addresses were made by members of the staff to Fish and Game associations, among which might be mentioned Dr. M. W. Smith's on "Problems of the Trout Fishery in the Maritimes" to the combined associations of the three Maritime Provinces on board the M. V. "Abegweit" in November. Mr. Hachey and the Direètor, as honorary members of the staff, gave a series of three seminars each on physical oceanography and fisheries biology at the University of New Brunswick in February. The senior class in biology and the summer school class in geology visited the Station for a day each. Biology classes from two local secondary schools (East Saint John and Calais, Maine) also visited the Station. Acknowledgements We are grateful for the continued co-operation of industry, of universities and of other agencies of both federal and provincial governments, and especially that of other branches of the Dominion fisheries service. We wish also to thank the scientists in other countries from whom we have received assistance.

***********#***** ORGANIZATION ************ (as of September 1, 1951, except for seasonals)

Director . A.W.H. Needier, Ph.D. Scientific Assistant to Director L.R. Day, M.A. A. Scientific and Investigational Staff 1. Lobster (including Shrimp) Sen. Scientist in charge D.G. Wilder, Ph.D. Technician II G.J.W. Sullivan Technician II R.C. Murray Assist. Tech. III L.G. Kervin Assist. Tech , III U.J. Walsh Assist. Tech. II W.W. Yorston Sen. Res. Assist. - Seasonal D.W. McLeese, M.Sc. 2. Oyster Assoc. Scientist in charge (also in charge of Dept. of Fisheries Oyster Culture field staff and Prince Edward Island Biological Station) R.R. Logie, M.A. Technician I A.A. Skinner, B.Sc. Main. Supervisor I P.C. MacCaull Jun. Res. Assist. - Seasonal P.L. Breau Jun. Res, Assist , A.J. Wilson, B.Sc. 3. Clam and Scallop (including Paralytic Shellfish Poisoning) Sen. Scientist in charge J.C. Medcof, Ph.D. Technician II J.S. MacPhail Jun. Scientist - Seasonal L.P. Chiasson, Ph.D. Groundfish Assist. Scientist in charge F.D. McCracken, M.A. Assist. Scientist L.M. Dickie, M.Sc, Technician II D.N. Fitzgerald Technician I M.F. Fraser eTechnician I R.J. Kerr, M.A.

Assist. Tech. II Jean M. Stuart, B.Sc. Stenog, IIA Shirley B. Cunningham Sen. Res. Assist. - Seasonal W.F. Black, B.Sc. Sen. Res. Assist. It • R.W. Wolfgang, M.Sc. Herring Sen. Scientist in charge S.N. Tibbo, M.A. Assist. Tech. III E.G. Sollows Assist. Tech , I Phyllis J. Gibson 6. Smelt Assoc. Scientist in charge R.A. McKenzie, M.A. Assist. Tech. III I.M. Jones

Assist , Tech. II Evelyn R. MacMillan 7. Trout Sen. Scientist in charge M.W. Smith, Ph.D. Assist. Scientist J.W.,Saunders, M.Sc. Assist. Tech. III C.R. Hayes Assist. Tech. II Emma A. C. Haskell, B.Sc. - ReMe Spence, B.Sc. Sen. Res. Assist. - Seasonal Jun. Res. Assist. S.E. Vass 8. Salmon Sen. Scientist in charge C.J. Kerswill, Ph.D. Sen. Scientist P.F. Elson„ Ph.D. Assoc. Scientist H.C. White, B.A. Jun. Scientist H. Godfrey, M.A. Assist. Tech. II H.W. Coates Assist , Tech. II P.R. Graves Jun. Res. Assist. - Seasonal P. Couillard, B.Sc , Jun. Res. Assist. - E. Harris, B.Sc. 9. Seals Assoc. Scientist in charge H.D. Fisher, M.A. Technician I B.A. Mackenzie 10. Fish taxonomy and distribution Prin. Scientist A.H. Leim, Ph.D. 11. Eel-grass Jun. Scientist - Seasonal A.R.A. Taylor, B.A. 12. Irish Moss Assist. Tech. II - Seasonal E.G. Nichols, B.Sc. 13. Miscellaneous (including Tuna, Museum and Library) Assoc. Scientist in charge L.R. Day, M.A. Clerk IIB M. Beryl Stinson 14. Statistical Consultant Assist. Scientist - Seasonal G.F.M. Smith, Ph.D. 15. Hydrographer Assoc. Scientist L.M. Lauzier, D.Sc. (see also Atlantic Oceanographic Group below) 16. Engineer Assist. Scientist C.E. Petite, B.Sc. 17. General Laboratory Assistance Assist. Tech. I Mary Holmes - 3 - B. Administrative and Maintenance Staff 1. Director's Secretary and Office Clerk IV Nina M. Parker Stenographer III Winifred E. Dougherty Stenographer IIA Lois G. McMullon Typist I (and switchboard operator) Mary E. Johnston 2. Accounts, Stores and General Administrative Officer II J.A. Rogers, A.C.B.A. Clerk III Frances L. Stinson 3. Buildings, Grounds and Boats Curator E.G. Rigby Main. Supervisor IV H.Y. Brownrigg Assist. Tech. II (Boatman) W.G. Carson Truckman F.E. Purton Caretaker III (Watchman) H.E. Lee Caretaker III (Groundsman) D.A. Stinson Caretaker III C.S. Tucker Caretaker II K.W. Johnston "J. J. Cowie" Technician II (Captain) H.H. Butler I t Engineer B.W. Hart Three additional crew "Mallotus" Technician II (Captain) V.K. MacDonald Engineer L.I. Cross One additional crew "Gulf Explorer" Assist. Tech. III (Captain) J.A. LeBlanc One additional crew "Pandalus" Assist. Tech. III (Captain) C.J. Bayers ******************** Atlantic Oceanographic Group (responsible to JCO) Principal Scientist (Senior Oceanographer JCO and Oceanographer-in-Charge AOG) H.B. Hachey, M.Sc, Associate Scientist H.J. McLellan, M.Sc. Assistant Scientist W.B. Bailey, B.Sc. Junior Scientist R.W. Trites, B.Sc. Assistant Technician III J.A. Sullivan, B.A. 'Assistant Technician II P.O. Hachey Assistant Technician I L.H. Brownrigg Assistant Technician I C.C. Cunningham Stenographer IIA Madelyn M. Meating Assistant Scientist - Seasonal D.G. MacGregor, M.A. STAFF ***** (To December 1st, 1951) (Total staff as of December 1st numbered 64, including 8 AOG) (Staff other than seasonals classified as of December 1st)

A.W.H. Needier, 0.B.E., M.A., Ph.D., F.R.S.C. Director A.H. Leim, B.A., Ph.D. Principal Scientist P.F. Elson, M.A., Ph.D. Senior Scientist C.J. Kerswill,.M.A.. Ph.D. Senior Scientist (seconded to Head- ' quarters) J.C. Medcof, M.A., Ph.D. SeniOr Scientist M.W. Smith, M.A., Ph.D. Senior Scientist S.N. Tibbo, M.A. Senior Scientist D.G. Wilder, M.A., Ph.D. Senior Scientist L.R. Day, M.A. Assoc. Scientist H.D. Fisher, M.A. Assoc. Scientist (on educational leave from Sept. 24) L. Lauzier, M.Sc., D.Sc. Assoc. Scientist R.R. Logie, M.A. Assoc. Scientist W.R. Martin, M.A., Ph.D. Assoc. Scientist (on leave of absence from July 1) R.A. McKenzie, M.A. Assoc. Scientist ! H.C. White, B.A. Assoc. Scientist L.M. Dickie, M.Sc. Assist. Scientist (term employment from May 22) F.D. McCracken, M.A. Assist. Scientist C.E. Petite, B.Sc., B.E. Assist. Scientist J.W. Saunders, M.Sc. Assist. Scientist W.F. Black, B.Sc. Junior Scientist (term employment from October 1) H. Godfrey, M.A. Junior Scientist (to October 1; half time from October 1) Seasonal: L.P. Chiasson, Ph.D. Junior Scientist (May 28 - Sept. 23) A.R.A. Taylor, B.A. Junior Scientist (April 23 - Sept. 20) G.F.M. Smith, Ph.D. Assist. Scientist (June 1 - Sept. 30) W.F. Black, B.Sc. Sen. Res. Assist. (May 7 - Sept. 30) D.W. McLeese, M.Sc. Sen. Res. Assist. (May 14 - Sept. 21) R.M. Spence, B.Sc. Sen. Res. Assist. (May 15 - Sept. 18) R.W. Wolfgang, M.Sc. Sen. Res. Assist. (May 1 - Oct. 31) P.L. Breau l .B.A. Jun. Res. Assist. (June 16 - Aug. 31) P. Couillard, B.Sc. Jun. Res. Assist. (May 10 - Sept. 9) E. Harris, B.Sc. Jun. Res.'Assist. (May 14 - Sept. 14) S.E. Vass Jun. Res. Assist. (May 15 - Sept. 15) A.J. Wilson, B.Sc. Jun. Res. Assist. (June 8 - Sept. 22) E.G. Nichols, B.Sc. Assist. Tech. II (June 29 - Aug. 28) Alfreda B. Needier, M.A., Ph.D. Volunteer Investigator Verna Z. Smith, M.A. Volunteer Investigator Mary E. Needler Volunteer Investigator E.G. Rigby Curator (on retirement leave from Nov. 1) H.Y. Brownrigg Maintenance Supervisor V P.C. MacCaull Maintenance Supervisor I F.E. Purton Truckman H.E. Lee Caretaker III (Watchman) (from July 26) D.A. Stinson Caretaker III C.S. Tucker Caretaker III K.W. Johnston Caretaker II W.D. Stuart Caretaker II (Watchman) (to July 25) J.A. Rogers, A.C.B.A. Administrative Officer II Nina M. Parker Clerk IV Winifred E. Dougherty Stenographer III Frances L. Stinson Clerk III . Shirley B. Cunningham Stenographer IIA Hazel L. Grant Stenographer IIA (from Sept. 10) Lois G. McMullon Stenographer IIA M. Beryl Stinson Clerk IIB B. June Field Stenographer I (to Sept. 1) Mary E. Johnston Typist I G.J.W. Sullivan Technician III D.N. Fitzgerald Technician II J.S. MacPhail Technician II R.C. Murray Technician II M.F. Fraser Technician I R.J. Kerr, M.A. Technician I (May 10 - Sept. 15) B.A. Mackenzie Technician I (from May 15) A.A. Skinner Technician I C.R. Hayes Assist. Tech. III I.M. Jones Assist. Tech. III L.G. Kervin Assist. Tech. III S.D. Sedgwick Assist. Tech. III (to Feb. 15) E.G. Sollows Assist. Tech. III (term employment from May 1) K.G. Sollows, B.Sc. As.sist. Tech. III (to Aug. 11) U.J. Walsh Assist. Tech. III Colleen C. Carten, B.Sc. Assist. Tech. II (from Oct. 15) H. W. Coates Assist. Tech. II P.R. Graves Assist. Tech. II Emma A.C. Haskell Assist. Tech. II (to Nov. 14) Evelyn R. MacMillan Assist. Tech , II Arlene R. McMorran, B.Sc , Assist. Tech. II (to Jan. 16) Jean M. Stuart, B.Sc. Assist. Tech. II (from Aug. 13) W.W. Yorston Assist. Tech. II Phyllis J. Gibson Assist , Tech. I Mary Holmes Assist. Tech. I Esther I. Lord Assist. Tech. I (* time to March 31; -- time from Nov. 16)

- 3 - H.H. Butler Technician II (Captain) V.K. MacDonald Technician II (Captain) (from April 23) C.J. Bayers Assist. Tech. III (Captain) J.A. LeBlanc Assist. Tech. III (Captain) W.G. Carson Assist. Tech. II H.F. Strum Master (to January 5) L.I. Cross Engineer (from Sept. 1) B.W. Hart Engineer H. Yarn Engineer (to Sept. 1)

Personnel of Atlantic Oceanographic Group with headquarters at Atlantic Biological Station H.B. Hachey, M.B.E., E.D.„ M.Sc., LL.D., F.R.S.C. Principal Scientist H.J. McLellan M• Sc • Assoc. Scientist W.B. Bailey, B.Sc. Assist. Scientist R.W. Trites, B.Sc. Junior Scientist (educational leave with half pay from Sept. 20) E.L. Graham Assist. Tech. III (to Jan. 23) J.A. Sullivan, B.A. Assist. Tech. III (from Aug. 1) P.O. Hachey Assist. Tech. II (April 1 - Sept. 22) L.H. Brownrigg Assist. Tech. I C.C. Cunningham Assist. Tech. I (from Dec. 28, 1950) Madelyn M. Meating Stenographer IIA D.G. MacGregor, M.A. Assist. Scientist (June 15 - Sept. 17) • 1951 PUBLICATIONS Bailey, W. B., and H. B. Hachey. "An Increasing Atlantic Influence in Hudson Bay." Proc. N. S. Inst. Selo XXII, pt. 4, pp. 17-33. Bailey, W. B., and H. B. Hachey. "The Vertical Temperature Structure of the Labrador Current." Proc. N. S. Inst. Sci. XXII, pt. 4, pp. 34-48. Battle, H. I. "A Morphological and Physiological Study of Developmental Processes in the Three- spined Stickleback (Gasterosteus aculeatus L.)." Accepted for J. Fish. Res. Bd. Can. Day, L. R. "The Herring, Alewife and Shad." Atl. Biol. Sta. Circ., no. 19. (in press) Hachey, H. B. "Physical Oceanography in Canada, 1948-51." Assoc. Ocean. Phys. Procès-Verbaux. (in press) Lauzier, L. "Effect of Storms on the Water Conditions in the Magdalen Shallows." J. Fish. Res. Bd. Can. (in press) r MacGregor, D. Go, and H. J. McLellan. "Current Measurements in the Grand Manan Channel." Accepted for J. Fish. Res. Bd. Can. MacPhail, J. S., and J. C. Medcof. "Survey of Bar Clam Resour- ces of the Maritimes." Submitted for Prog. Rept. Atl. McKenzie, R. A. "Greenland Cod (Gadus ogac) in Miramichi Bay, N. B." Accepted for 'Copeia". - McLellan, H. J. "Fluctuating Inshore Water Temperatu'res in I the Autumn." Prog. Rept. Atl. (in press) Medcof, J. C. "Modification of Drags to Protect Young Scallops." Prog. Rept. Atl., no. 52, pp. 9-14. Medcof, J. C., and J. S. MacPhail. "The Winter Flounder - a clam enemy." Prog. Rept. Atl., no. 52, PP. 3-8. Smith, M. W. "Further Observations upon the Movements of Speckled Trout in a Prince Edward Island Stream." Canadian Fish Culturist, no. 10, pp. 44-46. Smith, M. W. "The Speckled Trout Fishery of Prince Edward Island." Canadian Fish Culturist, no. 11, Pp. 1-6. -2 - Smith, M. W. "The Whitefish in Kerr Lake." J. Fish. Res. Bd. Can. (in press) Smith, M. W. "Limnology and Trout 4mgling in Charlotte County.Lakes, New Brunswick." J. Fish. Res. Bd. Can. (in press) Smith, V. Z. "Further Ostracoda of the Vancouver Island Region." Accepted for J. Fish. Res. Bd. Can. Wilder, D. G. "The Relative Toxicity of Certain Metals to Lobsters." Accepted for J. Fish. Res. Bd. Can. Wilder, D. G. "A Comparative Study of Anadromous and Fresh- water Populations of Brook Trout, Salvelinus fontinalis (Mitchill)." Accepted for J. Fish. Res. Bd. Can.

REPORTS DISTRIBUTED FROM THE STATION IN TEE "MANUSCRIPT REPORTS" SERIES IN 1951 No. 408 Thurber, L. W. Observations on the Attempts to Control the Greater Clam Drill, Polinices heros. No. 409 McLellan, H. J. Short Term Fluctuations in the Verti- cal Water Structure of the Gulf of St. Lawrence.

No. 414 Medcof, J. Co, and J. S. MacPhail. 1945 Investiga- tions - Clams and Oysters.

No. 415 Dickie, L. M. Boughton Island, P. E. 10 , Scallop Investigations 1946. No. 417 Lauzier, L., R. W. Trites and H. B. Hachey. Some Features of the Surface Layer of the Gulf of St. Lawrence. No. 418 Trites, R. W. Water Replacements on the Scotian Shelf. No. 419 Stevenson, J. A. On the Occurrence of Loligo Dealii (Lesueur) at St. Andrews, N. B., during summer, 1932. No. 420 Stevenson, J. A. Growth of the Giant Scallop, pun2QuIm grandis (Sol.), 1932. No. 421 Battle, H. I. Fundy Survey: The Mackerel Fishery. No. 422 Bailey, W. B., and H. B. Haehey. Hydrographie Features of the Strait of Belle Isle with a Preface on the Oceanography of the Strait of Belle Isle by A. G. Huntsman. No. 423 Chiasson, L. P. Scallop Investigations and Explorations In the Southern Gulf of St. Lawrence, 1950. No. 431 Rice, F. A. H. Experiments on the Preliminary Curing of Irish Moss, 1944. No. 432 MacGregor, D. G., and H. J. McLellan. Current Measure- ments in the Grand Manan Channel. No. 433 McLellan, H. J. A Survey of Water Conditions in the Grand Manan Channel in September, 1950. No. 434 Battle, Helen I. Contributions to a Study of the Life History of Hake. Spawning with Notes on Age Determinations. Nb. 435 McKenzie, R. A. Cod and Water Temperature. r No. 436 Borden, Mabel A. A. Contribution to the Study of Acmaea testudînalis (L.) No. 437 Davidson, Viola M. The Causation of Diatom Maxima. (a) . Report for 1926. (b) Report for 1927. No: 439 Godfrey, H. A Report en the Eel Investigation for 1950-51.

MISCELLANEOUS MANUSCRIPTS AND CIRCULARS 1 Day, L. R. "On the Trail of. the Bluefin" in Official Program of the 8th Annual International Tuna Cup Match, Wedgeport, Nova Scotia, 1951. Needier, A. W. H. Memorandum on Lobster Protection to Prince Edward Island Fisheries Development Committee. August, 1951. Tibbo, S. N. The Migrations of Herring. Multigraphed report to Committee on Biological Investiga- tions, as part of a Symposium on the Migra- tions of Marine?, Fishes, January, 1951. ARTICLES PREPARED FOR "TRADE NEVIS" Fisher, H. D. Seal Census. February Issue, 1951. Tibbo, S. N. Drift-net Fishing for Herring. March Issue, 1951. Kersvill, C. J. 1950 Miramichi Salmon Investigations. Or November Issue, 1950. Smith, M. W. Prince Edvard Island Speckled Trout. November Issue, 1951. Hachey, H. B. New Oceanogriuphio Vessel. November Issue, 1951.

INDEX TO SUMMARY REPORTS

Appendices LIAL Page

Lobster 1- 9 • 1 - 12 Shrimp 10 12 Oyster 11 - 16 13- 23 Soft-shelled clam 17 - 23 23- 28 Razor clams 24 28 Bivalves and public health 25 - 26 29 - 30 Bait worms 27 30- 31 Scallops 28 - 32 31- 36 Groundfish 33 - 40 37- i 5,4 Herring 41 - 46 51+- 65 Tuna 47 65- 68 . &nit 48 - 52 68 - 75 Trout 53 - 57 75- 85 Electrical fishing 58 85 - 87 Salmon 59 - 69 88.- 114 Seals 70 -78 114 - 135 Eel-grass 79 - 80 135 - 138 Records of occurrence 81 138 - 140 Fishing methods 82 140-- 141

Hydrography 83 - 83M 11.1.1 - 162

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BAN*, ir• , /5 LOC./0.0ot o .•. il000 r ,,•• .•• daelliaa4àg a s. s - • • : ••••• Appendix No. 1 LOBSTER POPULATIONS AND SIZE-LIMIT CHANGES Population studies were continued during 1951 at Grand Manan, N. B., Tignish and Miminegash, P. E. I., Port Maitland, Fourchu and L'Archeveque, N. S. Comparable data on landings, catch per unit effort, size distributions and fishing mortalities are now available for these six ports for the past seven years. Somewhat less extensive data have been collected at Capelin Cove, N. So, and Gabarus, N. S. The data for L'Archeveque, Capelin Cove, Fourchu • and Gabarus, adjacent areas on the outer coast of Cape Breton Island, are of particular interest. L'Archeveque and Capelin Cove have been "market lobster" areas since 1934 when the 3 1/16" carapace-length size limit was introduced. This limit was raised to 3 1/8" (about 9" total length) in 1942 where it has remained since. At Fourchu and Gabarus a minimum size of 6i" total length was introduced in 1940 and increased to 7" in 1942. This limit remained in effect at Fourchu until 1947 when canning operations ceased with the adoption of the 3 1/8" market-lobster size limit, Canning has

continued at Gabarus where the size limit has remained unl- e changed since 1942. The number of boats, total landings and catch per unit effort at these four ports since 1945 are shown in the accompanying table. At L'Archeveque, Capelin Cove and Gabarus, where the size limits have remained unchanged during the period of observation, the annual catch and the catch per unit of effort have remained relatively constant. At Fourchu the landings dropped drastically in 1947, the year the larger size limit was intro- • duced. This year was, however, a relatively poor year throughout the area investigated. Since 1947 the landings of market lobsters at Fourchu have risen, steadily, averaging 97,400 pounds in 1950-51 as compared to an average of 48,200 pounds fcr 1945-47, This 1950-51 average is slightly greater than the 1945-46 average landings of canners and markets combined. At 1951 prices (canners 18e, markets 380 the 1950-51 average catch would have a landed value one third greater than the average catch in 1945-46. Most of the field work at Fourchu, Capelin Cove and Gabarus has been conducted by R. C. Murray. The observations at L'Archeveque were made by W. W. Yonton. D, G. Wilder

L'Archemuml___ Camelin Cove Fourchu Gabarus Size limit: Size limit Size limit 7" 1945-46 • 3 1/8" 1945-51 3 1/8" 1945-51 3 1/8" 1947-51 Size limit 7" -1945-51 No. Mkts0 c/ue* No. Mkts. c/ue No. Can. Mkts. c/ue c/ue No. . Can. Mkts. c/ue c/ue boats cwt. mkts. boatS cwt. mkts. boats cwt.• cwt. can. mkts. boats cwt. cwt 0 can. mkts.

1945 12 409 103 3 185 -- 15 315 442 53 71 11•11• • OM, IM ■11M

■ 1946 14 438 72 11 561 -- 19 432 629 52 75 58 911 961 •• IMM 1947 15 303 86 12 389 91 14 374 64 58 531 590 39 43

1948 12 409 99 9 • 367 124 13 MI lib 624 MI> IMM 117 61 945 821 52 42

1949 13 393 78 8 450 124 • 13 791 MO MD 126 64 908 871 48 44

1950 14 410 79 7 413 123 18 alb MI, 931 ill. VW 124 55 1022 833 50

1951 14 395 85 7 366 128. 20 IBM 111» 1016 .1.1. 130 54 979 960 53 56

* Pounds per 100 trap hauls Appendix No. 2 LOBSTER GROWTH To determine the natural growth rate of lobsters, eight marking experiments have been conducted in six areas since 1947. The lobsters were sorted into five or six 1/8" carapace-length groups and distinctively marked by punching one or two 3/16" diameter holes through different sections of the tail fan. A total of 27,330 lobsters so marked have been liberated on the fishing grounds, principally during May and June. From November to June after one srmmer moulting period commercial catches were eamined for marked lobsters, a total of 2,419 being recovered. The results are summarized- . in the accompanying table. At Tignish and Lismore the marked lobsters were free on the average for about 11 months, at L'Archeveque for 11-1 months, at Abbott's Harbour and Port Maitland for 7 months and at Grand Manan for 6 months. In each experiment a few marked lobsters that had failed to moult were recovered. These have been excluded in calculating growth, it being assumed that virtually 100% of the lobsters in the size range marked would moult during a full twelve-month period. The average total length and weight of lobsters when marked and recaptured have been calculated from the corresponding carapace lengths by means of regression lines and are shown in the accompanying table. In each area only slight differences in growth related to sex or size were evident and no attempt is made to consider these differences here. In general the percentage growth is remarkably constant throughout the areas investigated. Nine-inch lobsters, however, off Grand Manan„ an area of low summer water temperatures, show a slightly greater percentage - growth than 7" lobsters off Tignish and Lise)re, areas of relatively high summer temperatures. This difference is related to differences In the size at maturity, some lobsters off Tignish and Lismore maturing at about 7" whereas at Grand Manan few lobsters less than 13" are mature. The natural growth of lobster larvae was determined by measuring fifty larvae in each of the first four stages caught off Richibucto, N. B., during August, 1950. The average carapace length of each stage ras as follows: Stage I - 1.92 mm., Stage II - 2.58 mm., Stage III - 3.40 mm., Stage IV - 4.43 mm. This indicates a growth of 34.4% from stage I to 31.8% from stage II to III and 30.3% from stage III to IV. These growth figures correspond closely to those given by Templeman for lobster larvae caught off Newfoundland but are much higher than the 18% calculated by Hadley for larvae reared In captivity.

Lobsters marked Lobsters recartured Growth Av. ..Av. 'Av. 'Av. total weight No. total weight Length Weight'Length Weight No. length ounces No. moulters length ounces inches ounces % P.E.I. 1947-8 2 9 446 7.00" 6.38 56 54 7.98" .9.66 0.98 3.28 14.0 51.4 It " 1950-1 3,502 6.94 6,28 337 333• 7.81 9.21 0.87 2.93 12.5 46.6 Lismore, N.S.1950-1 6,262 7.03 6.42 633 629 8.01 9.56 0.98 3.14 13.9 48.9 L'Archeveque 9 N.S.1948-9 3 9 431 8.78 13.58 193 178 9.89 20 ..18 1.11 6.60 12.6, 48.6 , Abbott's Hbr. 9 W.S01948-9 3 9 746 8.80 13.30 . 230 229 10.05 20.07 1.25 6.77 14.2 - 50.9 Port Maft1and 9 N.S.1948-9 2,901 8.83 13.44 145 121 9.92 19.33 1.09 5.89 12.3 . 43.8 Grand Manan 9 N.B. 1947-8 2 9 285 8.90 13.76 178 . 165 10.19 20.88 1.29 7.12 14.5 51.7 " 1950-1 2,757 9.08 14.71 647 622 10.40 22.29 1.32 7.58 14.5 51

TOTALS 27,330 2 9 419 2,331

- 5 - The tedious task of measuring, marking and culling the large numbers of lobsters involved in these marking experiments was ably carried out by field technicians Kervin, Murray, Sullivan, Walsh and Yorston. D. G. Wilder

Appendix No. 3 FACTORS LIMITING THE SURVIVAL OF LOBSTERS During the summers of i949 and 1950 the upper and • lower lethal temperatures and the lower lethal salinities were determined for lobÈters acclimated to different temperatures. Since mortalities that occur where lobsters are held commercially cannot be fully explained on the basis of lethal temperatures or lethal salinities alone, a study of the effects of low oxygen levels was started during the summer of 1951. Groups of ten lobsters were exposed to water containing various low amounts of dissolved oxygen. This low- oxygen water was obtained by exposure to a nitrogen atmos r in a specially constructed glass apparatus. Different phere values of dissolved oxygen were obtained by changing the rate of flow through the apparatus. Lower lethal oxygen tests were run at three levels of temperature acclimation: 8.0°C., 16.0°C. and 24.0°C. At each of these acclimation temperatures tests were run at approximately 0.4, 0.6, 0.8 and 1 0 0 cc 0 of dissolved oxygen per liter. The mortalities after 48 hours exposure to these test solutions may be summarized as follows: Acclimation temperature 8.0°C. 16.0°C. 24.0°C. cc.02/1. % Mort. cc.02/1. % Mort. Cc.02/1. % Mort.

0.4 100 0.4 90 0.5 100 0:6 100 0 0 6 40 0.7 100 0.8 50 0.8 10 0 0 8 6 0 1.1 o 1.0 o 1 0 0 o These data indicate that the 50% lethal levels for 48 hours exposure are 0.84 9 0.55 and 0.90 cc. 02/1 0 at 8, 16 and 24°C. respectively. It has been expected that the lethal oxygen level would be the least at the coldest temperature investigated, and the cause of the relatively high value for the 8.0°C. acclimated lobsters is unexplained at present. - 6 - Preliminary tests indicate that lobsters conditioned for a lowered oxygen content for four to five days survive longer than lobsters from fully oxygenated water when placed in lethal oxygen tests. Lobsters show a remarkable ability to recover from asphyxia. Specimens completely immobilized from asphyxia regained the apparently normal active state within two hours when replaced in normal conditions. The lethal oxygen levels given here were determined in the virtual absence of carbon dioxide and the low values found suggest the necessity of a study of the combined factors of low oxygen and high carbon dioxide tensions as related to the survival of the lobster. D. W. McLeese

Appendix No , 4 BLOOD CONCENTRATION OF LOBSTERS UNDER PHYSIOLOGICAL STRESS Lobsters were acclimated to 8°, 15° and 25° Centi- grade, and subjected in groups of four to physiological stress of higher or lover temperature and/or reduced salinity of 20 9 9 or 10 per mille. The blood concentration of these lobsters 15 was followed by analysis for blood chloride, and electrical conductivity measurements. These analytical procedures gave parallel results. In all cases of lowered salinity, the concentration of the blood fell to almost the concentration of the external medium; but, before this equilibrium was reached, the blood concentration went much lower and then came up again to about this external concentration. Experiments were not concluded until the lobsters had either died or survived for 96 hours. The results would indicate that lobsters acclimated to 8°C 0 can stand an external salinity of about 10 per mille, and the corresponding internal salinity of about 12 per mille when tested at 8°C 0 9 but if tested at 25°C 0 9 the lower limit of both internal and external Is higher. Similarly, lobsters acclimated to 15° or 25°C 0 will not withstand internal or external concentration as low as those at 8°C. The technical work for this study was performed by Miss Marjorie Myers, and part of the cost borne by the National Research Council.

G. F. M. Smith and M. Myers -a

Appendix No. 5 THE RELATIVE TOXICITY OF CERTAIN METALS TO LOBSTERS An experiment to determine the relative toxicity of copper, lead, iron, monel metal, zinc and aluminum to lobsters was started on May 23 9 1950. As the experiment progressed stainless steel was added to the series. Seven rater-tight tanks having inside dimensions of 41 x 41 x 8" were constructed of le dressed pine. Four- foot-square sheets of the metals to be tested were placed on the floors of six of the tanks, the seventh tank serving as a control. The tanks were then filled to a depth of 6" with 50 Imperial gallons of fresh sea water which was not changed during the course of the experiment, although on several occasions from 5 to 10 gallons of sea water were added to replace loss through evaporation. Oxygen was supplied by means of compressed air bubbled into each tank through two air stones at the rate of about one litre per minute. No attempt was made to control temperature which reached a maximum of 19 0 9°C 0 on July 13, 1950, and a minimum of -1 0 8°C. on December 21, 1950. Ten vigorous lobsters ranging in total length from 23 to 26 cm 0 were placed in t each tank. To delay the accumulation of organic decomposi- tion products the lobsters were not fed. The experiment was terminated January 2, 1951, because ice formation interfered with the observations. The experiment indicated clearly that copper, monel metal, zinc and lead were toxic to lobsters in that order, the average times to death being 14, 100, 181 and 251 hours respectively. Although none of the lobsters in the iron-floored tank survived to the end of the experiment the fact that seven survived for more than five months shows that this material is non-toxic. Six of the lobsters'held in the aluminim-floored tank survived for more than seven months and five of those held in the stainless steel tank survived for more than four months. D. G. Wilder f Appendix No. 6 LOBSTER HOLDING EXPERIMENTS F.; The excellent survival of lobsters in stagnant sea water oxygenated by means of compressed air as described in Appendix No. 5, together with reports that lobsters could be held satisfactorily in artificial sea water, stimulated holding experiments. If commercial quantities of lobsters could be held satisfactorily in artificial sea water for a week or more, inland marketing would be greatly facilitated. Only - 8 - three preliminary experiments have been conducted to date but the results are sufficiently promising to warrant further investigation. The artificial sea water tested was made up according to Schmalz's formula, a relatively simple mixture of five readily available salts, sodium chloride, potassium chloride, magnesium chloride, calcium chloride and magnesium sulphate. On January 25, 1951, ten vigorous lobsters were placed in a 41 x 41 x 8" wooden tank containing.50 Imperial gallons of artificial sea water. Oxygen was supplied by means of compressed air bubbled through two spherical 1 1/16" diameter air stones. All ten lobsters were alive and behaving normally on February 15 when the experiment was terminated (21 days). The average water temperature was 9.1°C 0 To determine the extent to which lobsters could be crowded, 78 vigorous lobsters (75 lb.) were placed in 45 gallons of artificial sea water on February 21, 1951. Oxygen was supplied by means of compressed air bubbled through five spherical air stones evenly spaced over the floor of the tank. Air was bubbled through each stone at the rate of about one litre per minute, sufficient to maintain the dissolved oxygen at about 75% of saturation. Only three deaths occurred to March 1 (8 days), but on March 2 the lobsters started to weaken and all died by March 5 (12 days). The average water temperature during the course of this experiment was 90 8°C. This water was then tested with nine vigorous lobsters and found to be very toxic, six of the lobsters dying within four hours. On March 6, 1951, a new experiment was started when 53 lobsters (52 lb.) were placed in 45 gallons of artificial sea water. On April 26, when the experiment was terminated (51 days), 40 lobsters (75%) remained alive, the same percentage survival as occurred in a control tank of running sea water. The average water temperature during this experiment was 10.4°C. These experiments indicate that lobsters can be held commercially in stagnant but aerated artificial sea water. Further work is necessary to determine the effect of higher temperatures on survival and to evaluate filtration as a method of cleaning the water to facilitate culling and possibly improve survival. Most of the observations involved in these experiments were made by R. C. Murray. D. G. Wilder Appendix No. 7 PROPOSED SIZE LIMIT INCREASES FOR MARKET LOBSTERS The Government of Massachusetts has passed legis- latiOn- which increases the minimum legal size of lobsters in that State - by- 1/16" à year for two years. On December 1, 1954 the minimum legal size will be increased from 3 1/8" . carapace length (9.0" total length) to 3 3/16" (9.2" total length) with a further increase to 3-1" (9.4" total length) effective December 1, 1952. Since Massachusetts is the principal outlet for Canadian live lobsters, these size-limit changes will have a marked effect on the Canadian lobster industry. To determine the immediate effect on landings if similar size-limit changes were adopted in Canada (now definitely proposed), a series of measurements was made in southrestern Nova Scotia during December, 1950, and April, 1951. In this area approximately 47,000 lobsters were measured to 1/32" carapace length. During June and July, 1951, an additional 1,000 lobsters were measured In district 6A, a small market-lobster area in Rich- mond County. The results are summarized by counties to show the percentage of the catch by count and weight that - falls between 3 1/8" and 3 3/16" and between 3 1/8" and 3e. No. and wt. legal- % of legal catch % of legal catch sized lobsters >between 3 1/8" between 3 1/8" measured and I 3/16" and 3 1/4" County No , Lbs. Count Weight Count Weight

Digby 6,118 7,788 10.6 7 0 7 21.9 16.4. Yarmouth 21,235 25,454 11.1 8 0 6 22 0 7 18.1 Shelburne 16,230 22 9 506 11.0 , 7.3 21.5 14.8 Queen's. 1,491 1,764- 12.5 9.8 24.7 ' 1909 Lunenburg 1,835 2,116 14.0 11.2 28 0 1 23.2 Richmond 1,038 1,292 10.4 7.7 20.1 15.4 Total and Av. 47,947 60,920 11.1 8. 1 22.4 16.8

4. The se data indicate that if the size limit were raised to 3 3/16" th e catch in that year would be reduced approximately 11% by count or 8% by reight. Similarly, if the size limit were raised to 3*" In one year the catch that year would be reduced 22% by count or 17% by weight. Most of the measurements involved in this survey were made by field technicians L. G. Kervin, G J. We Sullivan and U. J. Walsh with some assistance from R. C. Murray and W. W. Yorston. D. G. Wilder — 10 - Appendix No. 8 MINIMUM TAIL WIDTHS FOR LOBSTERS - In order to evade minimum size limit regulations, fishermen in certain areas have adopted the practice of dis7 Membéring live sub-legal lobsters - and selling . the separated' claws and tails. This practice could be curtailed to a certain extent by a regulation prohibiting -the possession of dismembered raw lobsters. Further curtailment would be possible . if a supplementary minimum size for cooked tails could be established. A similar minimum for cooked claws would not be feasible because of the great variation in claw size. To determine the minimum tail size corresponding to present minimum sizes which are based on total length (7") in the canning areas and carapace length (3 1/811 ) in the market lobster areas, a series of total length, carapace length, tail length and tail width measurements were made on live lobsters, dismembered raw lobsters, cooked lobsters and air-dried empty shells. Since It is now proposed to change the minimum legal size for canner lobsters from 7" total length to 2 3/8" carapace length and to increase the minimum for market lobsters to 3 3/16", tail sizes corresponding to these new minima have been calculated. Tail length is difficult to measure accurately both on intact live lobsters and on dismembered live lobsters. After cooking, the tail usually curls and the joints stiffen making it difficult to straighten the tails consistently. Air- dried empty tail shells become brittle and cannot be straigh- tened. For these reasons tail length is not a feasible measure of tail size. Tail width was measured across the ventral surface of the second abdominal segment to the outer surface of the . pleural spurs. The average and minimum tail widths corresponding to carapace lengths of 2 3/8" and 3 3/16" for lobsters measured alive was as follows: Tall Widths Carapace Males Females length n min.* n 2 min.* Tignish, P.E.I. 2 3/8" 36 1.29" 1.23" 36 1.38" 1.31" Gabarus, N.S. 2 3/8" 48 1.30" 1.21" 63 1.39" 1.32" Lismore, N.S. 2 3/8" 49 1.29" 1.24" 50 1.40" 1.32" Grand Manan, N.B. 3 3/16" 46 1.74" 1.67" 62 1.84" 1.76" * minimum = 2 - 1.645 x standard deviation In a normal 1ega3 catch very few lobsters would be exactly legal size. FIsheris officers would allow for a margin of error in measuring and several sub-minimum tails in a single

- 11 - catch would usually be considered necessary - for legal action. It appears, therefore, that for practical purposes the minimum tail width could be set at If" for males and 1 5/16" for females where the size limit will be 2 3/8" carapace length, and at 1 5/8" and le for males and females respectively where the size limit will be 3 3/16". Carapace lengths and tail widths shrink about one third of 1% on cooking, a difference that can safely be ignored in practice. D. G. Wilder

Appendix No. 9 PLANKTON TOWS FOR LOBSTER LARVAE The program of systematic towing started in 1948 to determine the relative abundance of lobster larvae in the Richibucto-Miminegash area of Northumberland Strait was continued in 1951 from June 16 to September 21. During this period a total of 338 half-hour tows were made using the specially designed 12'-wide surface plankton net constructe4 of galvanized pipe, metal floats and #16 grit gauze (16 meshes to the inch). First-stage larvae appeared in the tous on June 16, second-stage June 18, third-stage July 4, and fourth-stage July 13. In 38 tows made from September 8 to 21, only 5 larvae were taken, 3 in the first stage and 2 in the fourth stage. The total catches of each stage during July and August, the period of maximum abundance, have been as follows during the past four years. The catch per tow is given in parentheses. No. Stage Stage Stage Stage tows IV Total 1948 69 694(10.1) 297 (4.3) 178( 2.6 ) 131(1.9) 11 300(18.8) 1949 211 6,067(28.8) 802 (3.8) 3 28 ( 1.6) 79(0.4) 7,276(34.5) 1950 168 11,075(65.9) 3,048(18.1) 1 9 445(8.6) 37(2.0) 15,905(94.7) 1951 222 71 957(35.8) 1,570 (7.1) 692(3. 1) 433(2.0) 10 9 652 048 0 0 The relatively small catches of first-stage larvae in 1948 may have resulted from using an 8-mesh-to-the-inch net that yêar which possibly permitted some of the smaller larvae to escape. Since 1949 the catch per tow of first-stage larvae has not varied greatly, the best catch being only 2.3 times the poorest. If the figures since 1949 represent the relative abundance of the four larval stages, then only 1% to 5 of the first-stage larvae produced survive to the fourth stage. These tows were made with the M.B. "Gulf Explorer" skippered by Captain Ju1e5 LeBlanc. W. W. Yorston served as -12- observer during most of the towing period. . . . A further series of twenty-three i-hour to 1-hour surface tows was made by W. G. Carson on the M.B. "Clupea H." off Bocabec, Charlotte Co., N. Bo, from July 20 to 0ctober 9 0 In all of these tows only one lobster larvae was taken, a second stage caught on August 6. D. G. Wilder

Appendix No. 10 SHRIMP SURVEY Explorations for commercial quantities of shrimp (the pink prawn, Pandalus borealis) were carried out from 1947 to 1949 but discontinued in 1950 because a suitable boat was not available. In 1951 the survey was resumed off Canso, N. So, from February 5 to March 29, the area and time indicated by previous surveys to be most promising. During this period a total of 64 half-hour drags with a 50' shrimp. trawl were made in 15 to 100 fathoms. Some P. borealis were taken in 44 of the drags, but in the ten best drags all at 60 to 100 fathoms a total of only 190 pounds were taken. The best catch for a single drag was 42 pounds. As in 1949, these shrimp were relatively small, ranging from 2 0 6" to 5.8" in total length with only 27% of the catch by count exceeding 5". The shrimp fishery in Maine is based almost entirely on egg-bearing females which range in total length from 5" to 7li, and average about 6". In the 1949 explorations made off Canso during April, very few egg-bearing females were taken and on these the eggs were ready to hatch. This suggested that greater numbers of the larger egg-bearing females might be taken earlier in the year. However, only 17% by count of the 1951 catch carried eggs. Since 1947 a total of 295 half-hour drags have been made from the Wolves Islands area off Charlotte Co., N. B., to the Bay of Chaleur without revealing commercial quantities of shrimp. It now appears doubtful whether inshore concentrations of egg-bearing females, such as occur along the coast of Maine, will be found in our waters. It is planned, for the present at least, to discontinue these explorations. The 1951 drags were made by Captain Jules LeBlanc in the M.V. "J. J. Cowie" with U. J. Walsh assisting as observer. D. G. Wilder - 13 - Appendix No. 11 _ THE "MALPEQUE" OYSTER DISEASE - COMPARATIVE MORTALITIES IN MALPEQUE AND OTHER STOCKS For some years now we have been comparing the mortalities in the susceptible native and in the resistant Malpeque 1 stocks of the same year-classes held side by side in trays in 1 Johnston and Enmore Rivers, P. E. I. These two inlets are some sixty miles apart, but both were ravaged by the "Malpeque disease" between 1935 and 1940. In Johnston River the 1943 year-class has been discarded because of the paucity of oysters remaining on the trays, the 1944 year-class was lost three years ago in a storm and there were no Malpeque spat available in the 1950 year-class because of the failure of the set in that year. Also the observations taken on the 1946 year-class in 1949 and 1950 are obviously in error and must be omitted. We do, however, have data from the year-classes from 1945 to 1949 for the years from 1946 to 1951. Furthermore, a known number of spat (1900) was used in 1945 and a standard number (1000) in each year since, thus making possible a study of the accumulated mortalities year by year. The data have not previously been reported in this manner. In Enmore River it was necessary to re-commence the study with the 1949 year-class because of accidents which obscured previous results. Since this is as yet the only year- class available and has but two years' observations on it, the results are not very informative and are omitted. A large number of oysters were always dead when the trays were raised in the spring. They have always been considered as having died from other causes than the disease and were dismissed from the calculations as "winter-killed"; However, in reporting on another experiment of a similar kind (Appendix 10 to the Report of the Atlantic Biological Station for 1949 and Appendix 12 to the 1950 Report) it was found that the results were quite meaningless without the assumption that at least a large proportion of these winter deaths was attributable to the wasting effect of the disease. In the graph on page 14 the data are presented showing the mortalities from all causes. In the left-hand panel the accumulated mortalities in the Johnston River stock are shown in contrast to the mortality of one year-class of the Malpeque stock which can be taken as typical of mortalities in the Malpeque stock in ensuing years. In the right-hand panel the mortalities in three introduced New Brunswick and Nova Scotia stocks in Bideford River, Malpeque Bay, and of Malpeque oysters in the same river are shown in a similar manner. In Johnston River it is plain that the native and . .+1945 year class +Shippegan 100- o1946 year class ()Bras d'Or o' e 1947 year class eMalagash tu) al948 year class cMalpeque o 011949 year class 4.4 8CI- o A1945 Malpeques 0

7 0 0

rrs F., 0 / 47' 'n !C I e5o • ifl _------X 0

a if I -H• — /

0 / '3 0 I-

+> 1201—

O y/ ■ 10,_ • !v

1 5 6 2 3 4 oî exposure? disregaràing the spat year) Years Years of exposure MORTALITIES IN JOHNSTON RIVER MORTALITIES IN INTRODUCED OYSTERS

- 15 - Malpeque stocks are affected quite differently. With the exception of the 1949 year-class, for which only two Observations are as yet available, all the native stocks show a high degree of Susceptibility to the disease without any demonstrable develop- ›,A ment of resistance on the Malpeque scale, unless such a trend is indicated in the 1948 and 1949 year-classes. The disease follows

1-n the first year of exposure so weakens the oysters that many ' are unable to withstand the stress of hibernation. It is also clear that, instead of being irrelevant, the winter deaths are 4 the most numerous of those caused by the disease. It seems reasonable to suppose that the causative organism would be 1 present in its greatest numbers and in its most flourishing a condition in the first season of exposure and the following w inter. This then should be the most promising time to preserve living oysters for the identification of the organism. This lead will be followed up. In the right-hand panel of the graph is shown a very similar behaviour of the disease in New Brunswick and Nova Scotia oysters introduced in Malpeque waters. They are different in that the heavy mortality continues throughout the third year of exposure and in that the final mortalities are higher. However, when it is borne in mind that these oysters consisted of a mixture of year-classes as opposed to the uniform year-classes in the Johnston River experiment, and that the loci of the experiments differ, the similarities become more striking than the differences. It is again true that in every case the greatest mortalities occurred over winter. This reconsideratiow-of results has revised oùr ideas Of the nature of. the disease and has stimulated a renewed search for the causative organism. R. R. Logie

Appendix No. 12 OYSTER MORTALITIES IN WEST RIVER,. PRINCE EDWARD ISLAND The background of this investigation is set forth in Appendix 10 to the Report of the Atlantic Biological Station for 1950. During October and November of 1950, samples of from one to two barrels each were taken from the main bed in West River and were divided between cold storage in Charlottetown and Montreal. Samples of these were examined at approximately

W "4, - 16 - monthly intervals for symptoms of the "disease". It soon became apparent that the oysters could be divided into those rhich were: (a) living and apparently normal; (h) living and black-gilled; (c) dead, black-gilled and putrefying; and (d) dead and putrefying, but not black-gilled. Samples were .withdrawn from (a), (b) and (e) for histological examination. Oysters classified under (d) were of a sort normally encountered in cold air storage and they were disregarded in this investigation. In living black-gilled oysters it was possible to •select from any sample a series apparently showing the progress of this condition. It begins as an inter-filamentary darkening of the posterior portion of the gill lamellae and proceeds dorsally and ventro-anterially, darkening as it proceeds, until finally the whole gill surface is a dark greenish-black. Putre- faction follows rapidly in the wake of this condition. It seemed very likely that all oysters developing the discolouration would deteriorate in this way and finally die. Therefore careful records were kept of the numbers in (h) and (c) above at each examination. They were expressed as percentages of the sample and the results are shown in the graph on page 17. It is plain that, with one exception, the numbers of dead and black-gilled oysters, as shown by the dotted lines, did not increase steadily throughout the period of storage, as could be expected if the living, black-gilled ones eventually succumbed, but instead held to a level of 10% or less. The graph also shows that the numbers of living, black-gilled oysters rose to a peak and then fell off, indicating that some of these •oysters recovered from the condition. In view of the fact that the oysters were hibernating and that many were thin and possessed of little reserve food, this was a remarkable performance. It should also be noted that the severity of the condition and the peak of its incidence were very similar in five out of six cases and that the varying times of fishing and the different periods of transit to storage made no appreciable • difference to the outcome. In the two previous years, oyster dealers found that this condition reached its maximum at just this time of year, mid-January. All black-gilled oysters are unacceptable to the trade and, judging from examination which we conducted in the previous winter, the severity of the condition was about the same as last winter. Some slides of affected oysters have been examined. The black pigment leaches out in any fixative so far tried and the gill itself shows a normal structure, indicating that the discolouration is caused by an extra-cellular accumulation in the gill. However, the intestinal epithelium frequently shows a disorganized condition strongly suggestive of that claimed by Mackin (1951) to be part of the pathology of infestation by the fungus Dermocystidium marinum in the Gulf of Mexico. Speci- men slides have been obtained from Dr, Mackin which clearly show several stages of pf;rmoeystidium in various tissues, in- eluding intestinal epit-helium. This parasite has not been found Fished Oct 13

•■•

Fished Nov 1 L_ 45

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— — --f

Fished Nov 13

•••■• _- krh-i____q ewe- Fel b 2 4 9 k0 27 4 Held in Charlottetown storage oHeld in Montreal storae --- Black-gilled and dead ---- Black-gilled and alive MORTALITY IN WEST RIVER OYSTERS - 18 in West River oysters, but the very similar disintegration in the digestive tissues suggests that these too are pathologically caused by the invasion of the oyster by sonie parasite. The gross symptoms of the West River disease are quite different from those produced by infection with Dermocystidium, and it would appear that we must look for another organism. As 'soon as the Ice went in the spring of 1951 the test trays which had been held on the bottom of the East and West Rivers were raised and the oysters were examined. Winter mortalities were extremely light, being of the order of one percent, which is less than would be expected in normal oysters held in this manner. None of the dead nor any of a sample of the living exhibited any symptom of the disease. Periodic sampling of these oysters throughout the summer and fall of 1950 showed good growth and a negligible mortality. This was again true this year and we can now say that, over a period of some fifteen months, no oyster has been discovered in nature showing any symptom of the disease, although it developed rapidly in cold air storage. We can now suggest the following characteristics of the disease: (a) it cannot be detected by gross examination of oysters In their natural habitat during open-water months; (b) it must be present in such oysters and it must be there prior to the middle of October, since oysters fished on and after this date developed the condition in storage, in a manner irrespective of the time of fishing, the time in transit to storage, the storage itself or the time in storage; (c) it develops quickly in oysters in cold air storage but most of those affected are able to recover; - . (d) it is not very contagious, since it has not invaded the other Charlottetown rivers, in spite of the history of rapid spread of the Malpeque disease in these waters previously. It is possible that the explanation of the absence of this condition in oysters in hibernation in their natural habitat as contrasted with its prevalence in oysters hibernating in cold air storage Is resident in the fact that the former do occasionally open their shells and flush out the - shell liquor, whereas the latter cannot. The accumulation of nitrogenous wastes in tightly closed oysters undoubtedly lowers their vigour and renders them more vulnerable to attack, but it is difficult to understand how such oysters eventually recover, unless it be that phagocytosis goes on at an increased pace, regardless of other conditions. - 19 - It is planned to continue this investigation using only the Charlottetown storage. If possible, more frequent samples will be taken, and more attention will be paid to the various degrees of "blackness" in the gills. Histological examinations will be continued in an attempt to discover the causative organism and to describe more fully the pathology. R. R. Logie

Appendix No. 13 PROSPECTS FOR OYSTER FARMING IN THE RICHIBUCTO AREA, N. B. In co-operation with the New Brunswick Department of Industry and Reconstruction, the Board employed a seasonal assistant, Mr. P. L. Breau„ to investigate the possibilities of catching spat in this "river" system for possible later development in its lower reaches and its harbour. In view of the great scarcity of larvae, his task in prediction was very difficult and his catch of two larvae on thirty collectors was most disappointing. Mr. Breau did much useful exploratory work in searching out existing populations of oysters and in asses's-2 the potentialities of this system in good oyster bottom. ing It would appear that the upper reaches of Richibucto River between its confluence with St. Nicholas River and the entry of Mill Creek offer the largest population of potential spawners together with protection from the prevailing winds and that this area could be expected to be the best spat producer. The best maturing grounds lie in those portions of the channel bank that are free of eel-grass in the lower part of Aldouane River and in the Northwest Arm and in the Harbour itself. The ground about Indian Island is very good and that portion of it known as the Narrow Pass, a small strait between Indian Island and the mainland; is particularly outstanding. In general the probable picture seems to be one of seed production well up the main river and maturing in the Harbour. R. R. Logie

Appendix No. 14 FURTHER EXPERIMENTS IN THE REARING.OF OYSTERS ON TRAYS Last year and again this year attempts were made to test the efficiency of the fixed Dutch trays as against the usual floating trays with wooden covers and wire bottoms, using the growth of separated spat in them as the criterion, and also to test the effect of certain modifications designed to improve the circulation of water through the trays. Ex- periments were conducted at Ellerslie and Shippegan in 1950 -20 and at Malagash and Shippegan in 1951. The product, length times width, was used as a measure of size. The results in each year are confusing and it is obvious that other uncon- trolled factors are influencing the growth, but certain con- sistencies are emerging. It would appear that at Shippegan the growth in Dutch trays is superior to that in floating trays, whereas the reverse is true in Ellerslie and Malagash. In most cases the best tray was a floating one with wire sides, ends and bottom and a wooden top. It is unfortunate that the use of Dutch trays at Shippegan is difficult because of the hardness of the bottom, and that the wire floating tray described contains so little wood that it is difficult to float It. Neither of these superior trayssis therefore practical. Other measures such as the drilling of half-inch holes every three inches in the timbers of Dutch and floating trays and the construction of an "ail wire" Dutch tray produced contradictory and inconsistent results. At the moment there is no reason to abandon the conventional floating tray in favour of any other. R. R. Logie

Appendix No. 15 CONFLICTING SETTLEMENT OF BARNACLES AND OYSTERS Especially at Shippegan, sets of barnacles frequently interfere seriously with oyster settlement and the growth of the spat, sometimes even to the extent of nullifying a good spatfall. It has been empirically discovered in the United States, and later checked more carefully, that shells sprayed with DDT caught only slightly less oysters than untreated ones and many less barnacles. In 1949, a year of good spatfall, at Shippegan, N. Bo, collectors dipped in a 5% solution of DDT in "stove oil caught as many oysters as untreated ones and reduced the barnacle set per filler from 48o0 to thirty. In 1950 the set was so poor that It is doubtful whether the figures were significant, but they indicated that stove oil itself produced just as good an effect as 2% and 5% solutions of 50% wettable DDT powder in stove oil. This year the same doubt can be cast on the results but the general indication is that untreated collectors caught oysters and barnacles, whereas collectors treated with oil alone and those treated with the 2% and 5% solutions of DDT caught practically none of either. It is interesting to note that untreated collectors placed in the water for a day only each throughout. all of July and August in an effort to determine exactly when the oyster . and barnacle sets occurred caught not a single oyster or barnacle. Obviously a scarcity of larvae can play strange tricks. It will be necessary to continue these experiments into one or more years of larval plenty. R. R. Logie

- 21 - Appendix No. 16 LARVAL ABUNDANCE AND SETTLEMENT OF SPAT The study of vertical distribution of the oyster larvae was continued at the Prince Edward Island Biological Station in an attempt to obtain further information which might improve our spat catches. Observations were continued at the . two stations previously used in Kerr's work from 1948 to 1950 (Appendix 13 of 1949 Report). Fifty-litre water samples were taken at the surface and four-foot levels in Bideford River and at the four-foot level only in Trogt River, the top four feet having contained a greater concentration of larvae than the remaining'strata in each of the last four summers. Samples were concentrated more easily than in the past by agitating each thoroughly to insure dispersion of the larvae and pouring it into a porcelain Buechner funnel onto a dampened filter paper. After the larvae settled the water was removed by applying suction and the filter paper carefully removed and placed under a glass marked in centimetre squares. The larvae found in ten squares, chosen randomly, were counted and measured under the microscope, constituting a little better than 10% of all the larvae on.the paper. e The-following table summarizes the vertical distribution of the larvae for 1951 and the two preceding years at I the Bideford River station, the light sets making the less intensive sampling in Trout River of little significance. For convenience the larvae are divided into three size groups: straight-hinge; intermediate, including all stages between straight-hinge and 200 microns in height; mature larvae (ready to settle). The figures for 1949 and 1950 (taken from R. J. Uerr's report) are based on supposed "maturity" at 280 microns; 200 microns is believed to be a truer figure and was used in

1951. s. Number of larvae per litre over the larvae season

/2±21 2950 1951 Surface: i- All sizes 27.8 3.3 0.50 Straight-hinge 18.3 1.5 0.16 Intermediate 8.0 1.7 0.30 Mature 1.5 0.10 0.05 Four feet: All sizes 78.8 3.8 0.69 Straight-hinge 58.3 1.8 0.28 Intermediate 19.1 1,9 0.32 Mature 1.3 0.10 0.09 The sets produced per filler on commercial collectors in these years were: 1949, 2450; 1950, 400; and 1951, 200. A set of 1000 per filler is the minimum acceptable in -22 - commercial operations. From the above table it is clear that ' the numbers of mature larvae produced does not depend solely on the numbers of any younger stage. Also a successful set did not, in these limited observations, result from a concentration of mature larvae of less than about one per litre. The distinction between sampling a known volume of water and the ordinary sampling with a plankton net Is that this method is quantitative. It should therefore be possible, by the use of pump samples, to recognize, at least after the event, the times of greatest abundance of larvae of any size. If a sufficient body of data were accumulated to recognize minimum concentrations for a successful set, it would be possible to use this determination in predicting the time and intensity of spat settlement. The table below shows the timing of the peaks of concentration of each of the three size groups over the past three seasons. Predicted settlement Straight-hinge Intermediate Mature date from plankton tows 1949 July 6 July 15 July 23 July 20-27 1950 July 16 July 27 Aug. 4 Aug. 4-5 1951 July 4 July 16 July 23 July 27 It seems that a prediction of reasonable accuracy might be made by adding 18 or 19 days to the peak date for straight-hinge larvae; 8 or 9 days to the peak for intermediates and predicting immediately from the peak for mature larvae. These generaliza- tions do not hold as mell for 1951 as for the other two years if the predicted date is accurate. The actual numbers of larvae involved in the production of these peaks in 1950 and 1951 are so slight as not to be recognizable until well after the event. This study will obviously have to be continued to embrace a greater number of larval densities and spatfalls. Spawning as shown by the measurement of gonadal thicknesses before spawning and by examination of spawning -oysters was of at least average intensity. The first major spawning, in the first week of July 9 was sufficiently early and ample to produce a good set. Instead few larvae survived even to the straight-hinge stage and the set was a failure. Most areas caught a mid-August set as well, but these spat are so small that they cannot be properly separated from the collectors nor held on trays thereafter. The actual catches and the estimated numbers usable are shown below: Catch per Proportion Usable filler usable catch ' Bideford River, P.E.I. 200 All 200 Trout River, P.E.I. 700 All 700 Shippegan, N.B. 525 One half 260 Malagash, N.S. 2700 One quarter 675 Gillis Cove, N.S. 490 Two thirds 325 - 23- Warned to expect a very light set, the growers did not put out collectors and all the above were caught on the Department's test collectors. Under ordinary circumstances a set of less than 1000 per filler is unacceptable, but growers are mollified by exceptional growth in a lighter set. Such growth occurred in Trout River and Gillis Cove this year, many of the spat being of the size of a twenty-five cent piece by the first of October and some being as large as a half dollar, but even so the only set which approaches commercial value is that in Trout River. This is the second consecutive year of spatfall failure and the effect on the prodtiction of market oysters five or six years hence may well be serious. A study of hydrographie and meteorological records for the open water seasons of the past six years has failed to reveal any peculiarities of both the 1950 and 1951 seasons which might account for their failure to produce spat. There are certain anomalies in the 1950 season but the 1951 records were very similar to those of 1946 and 1948 when catches of 1500 and 2500 per filler respectively were made. It may be that the spawning of oysters and the growth of the larvae are not entirely responsive to such conditions, or it may be that physical factors outside the open water season exert an important effect on the srmmer s s developments; e.g. the suggested influence of winter temperatures on' the development of subsequent sexual products. The factors which may influence the survival of larvae to settlement remain unknowh and so vitally important as to constitute a most important subject for future investigation. Condensed from reports by A. A. Skinner and R. R. Logie

Appendix No. 17 HISTORY, PRESENT STATUS AND PROSPECTS OF THE CLAM INDUSTRY OF THE MARITIMES This study w as begun a year ago to provide a background for clear thinking about management of Industrial shellfish problems . that now face the Department of Fisheries. It was summarized in part in last year's report. In 1951 the analysis of all available statistics of the fishery was completed and the results collated with those of the Research Board's flat management experiments now under way on the Sissiboo River. The recent climb in annual production of "round" clams from 10 million to 25 million pounds in 1950 was brought about by the diggers continually extending their efforts to include new and previously unexploited grounds that had dense clam populations that have built up through the years. Almost

all the clam ground in the Maritimes has now been dug over once (Appendix 22) and accumulated stocks removed but the fishing pressure continues to be very high. Judging from the results of the management experiments on the Sissiboo River, we may expect a drastic reduction in catch within the next two or three years - probably a drop • to about half the 1950 production. This drop is likely to create a great deal of internal change in the industry and may easily lead to abuse of the resource by over-digging. Those responsible for conservation and management should be alert to this risk, insist on observance of size limits and be ready to impose other digging restrictions if these prove necessary to maintain continuous production at the highest possible . levels. Observations show that some grounds are being dug over several times a year. The Sissiboo experiments (Appendix 18) suggest that such excessive fishing pressures should be reduced by some system of management, the nature of which has still to be determined. • J. C. Medcof

Appendix No , 18 DIGGING FREQUENCY AND SUSTAINED YIELD OF CLAM FLATS The more important of the two management experiments under way on the Sissiboo River, N. Se, since 1946 is designed as a Latin square to show how the yields of plots, that were uniformly dug over in 1945, differ when they are subjected to thorough digging at different intervals. The yield of commercial-sized clams per digging and the mean annual production in buckets (1.2 pecks each) per quarter acre of flat are shown in the following table, listing data for three of the six years concerned:

1946 1949 l9O 1951 ;-I 0 -1-) 4-) 4-) -P e a 0 to e ;-I e to 0 o o 0 to o a) o 0 o o e 4-1 cil rt4 0 sa, to H P4 tb3 H S:14 il0 H .ri -I-) Ei ..-t P 0 0 c3 I—I e cor-i .--r yie e 0 r—I Z 0 0 0 FA •r4 0 r-I › as rd •• °I-i > 03 'Ld *ei › C13 'CI "-I H H gi 0 VI C) tO .1-4 0 8-1 0 C.0 or-i r--1 0 ta0 n-1 0 H te td) 4-) t.0 0 e o 4) bi 0 CD 4-7 tà0 o e o a o 'et ti e4-1 Cd •r-i 04 e or-I 0 .r-1 Ce P eri cd ori CM e .ri CD 0 ci-t a' C r-i P tx.i 0 c..) rd rel St1 >> tJ li LA 03 >a C.) 'CI ell «3 >f Ç4 Pi 0 ca •rl P4 Twice per yr. 74 148 10 0 5 21 21.5 43 11 Once 116 per yr. 116 30 30 21.5 2105 20 Once in 2 yrs. 106 53 - - 86 43 21 Once in 69 23 3 yrs. 283 94 -- 53 - 25 - Conditions have not yet reached equilibrium because hardly enough time has elapsed since the experiment began for one generation of clams to settle and grow to fishable size under the treatments that are prescribed for the various plots. An - idea of what may be expected was obtained in October, 1951, from counts of all clams more than 1" long screened from representative 4-square-foot areas within four of the sixteen experimental plots. These results are listed in the last column of the table. The records show that there has been an almost consistent downward trend in the most frequently dug plots and that the density of surviving clams per square foot there is less than in any of the other plots. We may therefore conclude that two complete diggings per year is likely to produce lower total annual yields than can be obtained by less frequent digging, but we cannot say yet what frequency is likely to give the highest yield. Because production has not levelled off it will be worth while continuing the Sissiboo experiments for several more years. Similar experiments that are now under way at St. Andrews, N. 1309 and Chezzetcook, N. So, have not progressed far enough to provide a clear picture of trends. The soil con-, ditions„ especially, are different in these areas. e J. Co Medcof

Appendix No. 19 THE "EFFICIENCY" OF CLAM DIGGERS For intelligent handling of management problems such as the selection of a size limit, it is important to know, among other things, what proportion of the a:vailable stocks is removed each year by the fishery. This proportion expressed as a percentage is often referred to as "fishing mortality". To measure this, in the case of clams, we must first of all determine the proportion of the commercial-sized clams a digger takes when he turns over a piece of ground (this we have termed the "digging efficiency") and second, the proportion of the available ground that is turned over in the course of a year. For want of a better term we refer to the latter as the "rate of turning". The rate of turning is not easy to measure in many cases and is especially hard in intensely fished grounds where the same soil is turned over several times in the course of a year. Digging efficiency, on the other hand, can be simply, although laboriously, measured by counting the catch a digger takes from measured areas and then screening the soil he has turned and counting the clams he has missed. Twelve determinations involving the screening of the upper 8 to 10 inches of soil from 16 square feet of flat at each determination have been made which show that digging efficiencies vary from 30% to 90% but average 60%. They vary from digger to "--"1

- 26 - digger and with the type of soil. The efficiency is usually lower in crumbly sand than in sand-mud or in gravel-mud which both tend to stay together in clods when turned. So far a satisfactory measure of rate of turning has not been obtained in any area but we have a few estimates based on general observations which suggest that fishing mortalities of 60% are common on our flats and that they often range much higher. Incidental"to these measurements we have determined that on the average 7% of the clams left in the soil have broken shells and will probably die as a result and that 15% of those left are visible on the surface and therefore susceptible to attack by gulls or other enemies before they work their way back into the soil. It is planned to continue this study next year. J. C. Medcof

Appendix No. 20 CLAM "DIGGING" WITH OUTBOARD MOTORS In several parts of the Gulf of St. Lawrence there are extensive clam beds that are seldom or never exposed at low tide but the water level does fall enough that one can usually wade over them at low water. In 1949 an attempt was made to develop a method of harvesting these with a modified hydraulic bar-clam dredge but this was unsuccessful for two reasons: a high proportion of the clams were broken, and the costs of dredge operations were too high. This summer the use of the water blast from the propellers of outboard motors attached to skiffs or rafts was studied and it was found that these submerged stocks could be harvested inexpensively from sandy soils on calm days without apparent damage to the flats and with very little breakage. After the clams are washed out they lie on the surface of the bottom and may be picked up as soon as the water clears.

When fishing with motors is carried out systemati- cally the flats are not seriously furrowed and they are quickly levelled by wave action. Few adult clams are wasted in this method and the small clams that are left behind work their way back into the soil very quickly. There was no evidence smothering. of

It is being recommended that this method of harvesting be made legal in some areas for a fey years to see what effects it has. It holds promise because these stocks readily be exploited by other means. cannot

J. C, Medcof - 27 - Appendix No. 21 FLOUNDERS AS CLAM ENEMIES The study of winter flounders as clam enemies was last reported on in 1949 but has been continued since. Counts of seed clams in stomachs show that the fish take them from early spring until late autumn. Mr. McCracken has made available his records of numbers of flounders trapped in a tidal cove near the Biological Station and we have measured the area of the clam-bearing parts of this cove. From these data we have calculated that in the course of a single month the flounders alone could reduce the density of the seed clam population by 8 per square foot. An effort was made this year to measure this destruc- tion more directly by comparing the eurvival rates of seed clams inside and outside flounder-proof fences erected on the inter- tidal beaches at St. Andrews, N. B., and at Sissiboo and Chezzet- cook, N. S. The results are not yet available but the records should be helpful in judging the importance of this enemy. J. C. Medcof I !Appendix No. 22 EXPLORATIONS FOR UNUSED CLAM STOCKS Explorations for unused stocks and encouragement of the industry in exploiting them has been an essential part of the soft-shelled clam investigetions for several years. In 1951 Ye. MacPhail visited several new areas in Nova Scotia: the Bras . . d'Or Lake, St. Ann Bay, Ingonish Bay and Morien Bay. Only in the last rere the quantities found to be of potential commercial importance and even there the beds are so small that they would - permit only a small-scale seasonal operation. Furthermore, the quality of the meats was not high, although this.may improve with digging. He revisited the much larger and previously unexploited area he dlscovered in 1950 about Lennox Passage, N. S. As a result of our work a small but vigorously expanding clam shuck- ing industry has already sprung up_there. In the five-month period ending July, 1951, 407 barrels of clams have been harvested and the resulting income to the commilnity has improved the lot of its inshore fishermen and provided plant employment for others. J. C. Medcof - 28 - Appendix No. 23 CLAM FARMING TRIALS In last year's report it was indicated that clam farming was "out" so far as the Maritimes as a whole are concerned. This year's results confirm this earlier conclusion. A tenth-of-an-acre plot on the Cocoa Sands flat in Musquodoboit Harbour, N. So, was planted with 15 bushels of le clams in June, 1948, and dug out in June, 1951. Those that were recovered showed a 30% length increase since planting and all exceeded the size limit. However, the survival was so low that only 4 bushels, 27% of the volume planted, were recovered. Counts of the clams per bushel at planting and at harvesting show that only 14% survived for the three years. Two plantings on other areas, which like Cocoa Sands were considered more promising than most, remain to be harvested. No new plots were set out this year. J. Co Medcof

Appendix No. 24 TEE POSSIBLE COMMERCIAL USE OF RAZOR CLAMS For several years now razor clams (Ensis directus) have been used commercially in the New England States. Of late years supplies of soft-shelled clams, which are also used for chowder, have dwindled there and the fishery for razor clams has consequently assumed greater importance. We have long known of extensive stocks of razor clams in the upper end of St. Mary Bay, N. So, but industry has consistently neglected them. This year soft-shelled clams have . become acutely scarce in Digby County and we tried to interest shuckers and canners in the possibilities of exploiting razor clams to maintain the volume of their production. A trial run of a sample we supplied a Digby shucker was disappointing because of low meat yields per bushel of whole clams and low market prices for the finished product. However, one canner we have interested in the resource has produced attractive trial packs of whole canned razor clam meats and of canned chowder made with minced steamed razor clams. These have been so well received that he expects to pack several hundred cases next year. We propose continuing our interest in this development and will do whatever else we can to foster it. J. C. Medcof Appendix No. 25 CLEANSING SEWAGE-CONTAMINATED CLAMS Almost every year the area of clam ground closed to digging on account of sewage contamination is increased as a result Of the constant checks by the Department of National Health and Welfare on our shellfish areas and the increasing tendency of municipalities to dump raw sewage into our harbours. This year the whole of the Magaguadavic River in Charlotte County, N. B., was closed. This and other inlets have extensive flats that build up dense clam populations as a result of such protection. The discovery of some means of cleansing clams that would render them fit for market has long been dreamed of as a dual benefit. First, it would Increase the industry's income and, second, it would remove the risk that results from the trickle of these polluted shellfish which constantly find their way directly to markets through "bootleg" channels in spite of the best efforts of the officers of the Department of Fisheries. The Fisheries Research Board and the Fish Inspection Laboratory are examining the cleansing problem and conductedt a series of experiments in 1951. The results are not yet available in final form but we have shown that when polluted clams are exposed to relatively clean water they quickly lose their load of coliform bacteria. It is hoped that a procedure can be developed which will find industrial application. J. C. Medcof

Appendix No , 26 PARALYTIC SHELLFISH POISON In 1951 this Station continued participation in the management of the shellfish industry which is Made necessary by the periodic appearance of paralytic shellfish poison on this coast. Sampling programs rere arranged in Nova Scotia, New Brunswick, Quebec and Newfoundland in which the Fisheries Research Boerd, the Federal Department of Fisheries and the Quebec Department of Marine Fisheries participated. It is expected that within another year the Depart- ment of Fisheries through its Fish Inspection LaboratOry will assume responsibility for most of this organizational work which the Board's investigators have carried on for nine years. This year the Department engaged Mrs. R. Lord for the period May 28 to November 15 as an Assistant Technician Grade I to work at the Station under the writer's supervision preparing extracts and doing the necessary records work. A detailed year-by-year summary of the work done since 1943 was begun - 30 - some time ago and is now complete up to the end of 1948. Seven " copies of each of these six reports have now been circulated to those concerned with the management program. This permits ready reference to what is known about the several shellfish species tested in different areas and the results of the numerous experiments which have been conducted but not formally reported on elsewhere. For the first time in the eleven years for which records are available there ras no important summer rise in the toxicity of shellfish in the Fundy area. We have no explanation for this. No seasonal closures were imposed except in Annapolis Basin, N. S., where there was a questionable record of a low score and a brief closure. The industry was much pleased to have suffered so little interruption. All the Newfoundland samples tested were poison-free and the few April lots which were the only ones submitted from Quebec this year were likewise non-toxic. Research on paralytic poison is greatly reduced compared with earlier years because we have now an understanding of the problem that is sufficient for effective control. This year, however, we did show that rough whelks (Buccinum undatum), as well as other carnivorous snails, are capable of extracting and storing poison from toxic bivalves on which they prey. It may therefore be hazardous at times to eat whelks as well as bivalves in affected areas such as Matane County, P. Q., where, as in Europe, whelks are considered a delicacy. Another 1951 discovery, of academic rather than of practical significance, is that all extracts of greater clam drills (Polinices heros) prepared so far have proved toxic to mice. Since several of the samples tested came from areas where poison is unheard of yve have concluded tentatively that some element in these extracts other than paralytic poison is responsible for having killed the mice. No special program is planned for next year. J. C. Medcof

Appendix No. 27 DIGGING MARINE WORMS FOR BAIT The bloodworm (umurn) and the sandworm (Nereis) are used extensively in the salt-water sports fisheries in the New England States. In the State of Maine many one-time clam diggers are directing their entire efforts to digging these worms for air shipment to distributing centres. This work provides remunerative employment and eases the heavy fishing pressure on dwindling clam stocks. - 31 - A similar diversion of employment'for clam diggers in the Maritimes would also provide supplementary employment and be beneficial to our overworked clam flats. For this reason, several portions of our coast were explored this year for potential commercial quantities of these worms and for growths of packing weed for their shipment. No commercial quantities were found in Hillsborough Bay or in inlets on the east coast of Prince Edward Island. However, in Shelburne and Yarmouth Counties in Nova Scotia the bloodworm (Glvcera) was found in what were considered to be commercial quantities. While worms were found in Little River, Goose Bay, Wedgeport, Pubnico and Jordan River, commercial exploitation at present seems possible only in Little River and Goose Bay. Here there are at least a thousand acres of flats exposed at each low tide and the preliminary examination of these showed that substantial areas were populated with worms. There was also an abundance of packing weed (Ascolphyllum mackaii) and conditions in general seem to be as promising as any we are likely to find on our coast. In one trial an inexperienced digger gathered between 400 and 500 worms (probably worth about $1,50 per hundred) during one low tide at Little River. It is probable that this number could be raised as digging efficiency, knowledge of the best e localities and numbers of persons involved in the fishery increased. Trial shipments of these Little River worms by air freight from Yarmouth, N. So, to a bait wholesaler in New York proved that worms from this area can be marketed in good condition in spite of the distance. However, they were not readily accepted by the trade because the worms were smaller than those . regularly received from Maine. Nonetheless 9 we believe that if more bait dealers and fishermen were acquainted with these stocks a market could be developed for them. It seems pointless to make further explorations until the possibilities of exploiting the Little River stocks are more thoroughly tested. For this reason, the program proposed for next year includes only a visit to New England to make suitable contacts with bait dealers and further trial shipments timed, if possible l e to coincide with periods of bait shortage which would provide the best opportunities for demonstrating the value of Canadian supplies. J. S. MacPhail

Appendix No. 28 FORECASTS OF DIGBY SCALLOP PRODUCTION . Reliable forecasts of general trends in a fishery are useful both to industry and to government agencies responsible

- 32 - for fisheries management. Forecasts of Digby scallop production were seen as a possibility in 1948 when it was shown that the abundance of commercial-sized scallops (mostly seven-year-olds) determines production and indicated that the abundance of young scallops born each year is to a large extent determined by hydrographie conditions at spawning time. ' In 1948 the catches were low but it was predicted from what was known of hydrographie conditions in 1945 that there would be a recovery in catches that would be under way by 1952. The reliability of this 1948 prediction and of the method of prediction in general has been examined every year since by a three-day dragging program in which the stocks on the more important beds are assessed by counts of scallops of various sizes taken in series of standardized hauls made at regular intervals across the beds. This method of checking is an adaptation of the "strip-census" method used by timber cruisers in estimating potential cuts on forest plots. The results of the three surveys made to date are tabulated below. Average total counts and the size composition of scallo2 catches made in standardized 15-minute tows on five of the more important beds and the fleet's average annual catch per boat

191+ 1950 1951 No. No. No. Total No. <4" No. Total No. <4" No. Total No. <4" No. catch >4" >3" <3" catch >1-0 >3" <3" ,catch >4" >3" <3" Buoy Ground 155 132 4 19 227 120 55 52 385 135 104 146 Broad Cove Ground 164 134 5 25 133 93 20 20 175 101 25 49 Gulliver's Cove Ground 227 202 9 16 250 150 47 53 40-Minute Ground 230 184 34 12 397 262 103 32 Offshore- Hour-Ground 537 346 179 12 927 538 333 56 681 415 211 55 Average Annual Catch per Boat 7,100 11,400 ( ounds In 1949 the test catches were low and composed mostly of large animals on all beds except the offshore ground. The fleet's catch per boat was also low that year, much of it coming from the well-stocked offshore grounds. In 1950 the test catches were off Broad Cove, not because legal-sized scallops heavier except vere more numerous but because sub-legal sizes were then abundant. The fleet's catch was heavier that year because the fleet went to a large well-stocked area, the 40-Minute Ground, not recognized previously as important, and to the Offshore Ground. The 1951 - 33 - sampling shows a general increase on most inshore beds partly because legals are more abundant but principally because sub- legals are now present in better numbers than in either of the previous years. From these data we may anticipate a slightly higher catch per boat in 1951 than in 1950; a more substantial increase in 1952 is predicted if the fishermen will only abide by the legal size limit. It is proposed that yearly assessments be made a regular feature of the scallop investigation because they yield such desirable information,. L. M. Dickie

Appendix No. 29 FACTORS INFLUENCING DIGBY SCALLOP CATCHES Everyone concerned with the Digby scallop fishery knows that tàere are remarkable variations in the fleet's landings both from year to year and from month to month in any one year but few are aware of the nature and causes of these changes except in a vague way. Recently Mr. E. B. Richardson of National Sea Products, Digby, N. S., made nine years' detailed records of his transactions with scallop boat cap- tains available to the Fisheries Research Board for analysis. These data, cdmbined with statistics compiled by the Depart- ment of Fisheries, show that changes in the abundance of scallops are mainly responsible for year-to-year differences in landings but that weather and the per-pound market value of scallops and the fishermen's disregard of the size-limit regulations also play a part. Vie were not aware till now of the remarkable and regular month-to-month variation in landings of individual boats during any one season: 42% of the catch is taken in October and November, the first two months of the seven- month season; 25% in the three winter months combined and 33% in the last two months. Mr. Richardson's records show that changing vcather conditions are principally responsible for these month-to-month variations in landings. They are also affected to a small extent by within-season changes in Df abundance of scallops which are brought about by the fishery I s itself, but only very slightly, if at all, by changes in the per-pound market value of scallops. These findings help to provide a good basis for clear thinking on management problems. L. M. Dickie Appendix No. 30 "SAVINGS GEAR" TO PROTECT YOUNG SCALLOPS. In the reports for 1949 and 1950 the need for a modification of the present standard type of Digby scallop gear was pointed out. Too many sub-legal-sized scallops are now being taken and shucked regardless of the minimum legal size limit. The best way of insuring observance of the size limit seems to be modification of the gear so that few sub-legals are brought up. To this end three experimental modifications were tested against the standard in October, 1951. Mr. W. W. Yorston assisted Mr. MacPhail and the writer in this work. One of the three experimental meshes is essentially like the standard except that the wire rings have a 3-1" instead of a 2 5/16" inside diameter and it has performed very well. Compared with the standard it takes only half as many sub-legal- sized and 10% more legal-sized scallops. It is proposed to have a complete set of drags with this style of mesh made up and fished next spring on a commercial scale in comparison with the standard. J. C. Medcof

Appendix No. 31

SCALLOP EXPLORATIONS AND INVESTIGATIONS IN THE GULF OF ST. LAWRENCE The 1951 work in the Gulf was of three sorts. Likely places were explored for new beds; beds discovered in 1949 and 1950 were re-examined and, lastly, the efficiency of small gear hauled by lobster boats was compared with that of Digby-type gear hauled by a regular Digby-type scallop dragger. Explorations with "My Boys", a chartered Digby-type dragger, were conducted in the Gulf off Cape Bear, P. E. 1 0 1 N. S., and Caraquet„ N. B., and just outside the Gulf- Arisaig, off Port Morien, Lingan, New Waterford, Great Bras d'Or and in St. Ann Bay. No new beds were discovered. A gasoline explo- sion wrecked the boat and brought the explorations to an end after six and a half weeks. They would have continued, otherwise, for another week and a half. Checks on previously-known beds involved observations on abundance, size composition, growth and mortality rates of scallops. The two-squarea-mile Richibucto bed, discovered in 1950, is still well stocked throughout and there are no signs of recent serious mortality such as were observed last year. The scallops are all of approximately the same size and should - 35 - be 3-b" in diameter and therefore worthwhile-fishing commercially by the summer of 1952 if survival continues to be good. Over 80% of the stock present in 1949 on the bed just west of Pictou Island when it was discovered has been removed by a small amount of fishing in 1950 and repeated mass mortalities. However several abundant year classes of younger scallops have appeared and these should support a commercial fishery by 1954 If they survive. When discovered in the summer of 1950, the bed to the east of Pictou Island was populated by a single abundant year class. This stock suffered some mortality in 1950 and was intensely fished in the autumn of 1950 and the spring - and summer of 1951. It is now so depleted that fishing has ceased. There are no younger year classes present and it seems unlikely that the bed will be commercially .important for several years to come. Efficiency tests with small drags of types used in Charlotte County, N. B., and Lunenburg County, N. S., showed that both fish fewer scallops than Digby gear but they cost less and they are cheaper to operate when used from the common southern-Gulf types of two-man lobster boats equipped with trap haulers. Of the smaller types, the Lunenburg drag is the more easily handled and should be quite satisfactory for local fishermen who wish to use their lobster boats to exploit the spasmodi- cally productive scallop beds of this area. It is desirable to continue checks of known beds for another year using Lunenburg County gear. This would enable us to advise fishermen who are just beginning and not yet familiar with the grounds or fishing methods, as to what beds are worth working and at the same time demonstrate'the practicability of - scallop fishing from lobster boats to those who exhibit interest. At the same time these checks would supply much-needed data on mass mortalities which pose such a vexing problem in the Gulf' area. L. P. Chiasson

Appendix Nd. 32 TEE UNDER-WATER CAMERA AND SCALLOP CENSUS Last year an effort was made to test the usefulness of an under-water camera in the census of Digby scallops. It was hoped that it might yield direct information on abundance to supplement or replace that now obtained from our expensive and laborious system of systematic trial dredging. Some of thé limitations of the camera were discovered that year and in mid- August, 1951, the same instrument was given a four-day trial in the Gulf of St. Lawrence. - 36 - The purpose of the trial ras to see if some of these limitations could be circumvented but the test failed for no good pictures were obtained. The appearance of the exposed plates suggests that light-scattering by plankton was responsible for the failure, in spite of the fact that the water transparency, as indicated by Secchi readings made during the test, was well within the limits for satisfactory performance of the instrument claimed for it by the designers. Water transparency Is greater in early spring and late autumn than in summer and we plan to make further trials at these seasons. Vie believe the camera may have important possibilities for usefulness in investigations of bottom species.

J. C. Medcof - 37 - Appendix No , 33 STATISTICS OF THE OTTER TRAWL HADDOCK CATCH , The annual - _catch of haddock has shown wide fluctuations as is apiparent from the accompanying Figure 1. During the 1914-18 war the haddock catch increased to 71 million pounds but eince -that-time.only-in the-years 1926, 1929 and 1948 did catches exceed 50 million pounds. In the years 1921, 1933, 1942 and 1944 the annual catch dropped below 30 million pounds. Previous reports have shown that landed value, efficiency of capture and exploitation of new grounds all play a part in the magnitude of the haddock catch e but that abundance on grounds already fished is of primary importance as a factor In determining catch. Although detailed records of effort, growth, year- class abundance and mortalities have been collected only since 1945, short-term biological investigations by Needler and Thompson in earlier years have shown the importance of abundant year-classes in the haddock fishery off Nova Scotia. .1.1easurements'of_catch -per trip and catch per day ai sea are.available -frémlepartmerit of.Fisheries records for , otter . trawlers back to 1931. The four largest steam trawlers which havé carried but - contintioUs year=round fresh-fishing operations were selected as an index of changes in abundance. Average catch per trip for each year of large and scrod haddockis shown in Figure 1. A high catch per trip of scrod in 1934-35 was associated with a high catch per trip Of large haddock in 1935-38. A lesser scrod peak in 1939-41 was associated with an increased catch of large haddock in 1942-43. An increased catch per trip of scrod beginning in 1947 is associated with an increased catch per trip of large haddock in 1948-50. The total otter trawl catch of scrod and large haddock from 1947 through 1951 for the January to June period is also shown in Figure 1. Total catch of large haddock has remained approximately the same since 1948 with the scrod catch increasing markedly in 1951. Age composition data for haddock from Batiquéreauestern:Bank and St. Pierre Bank (Figure 2) - indicate:that the 1946 year-class makes up the major portion of . this - scrod - catch. An.increased scrod catch indicates_arelatively_strong year-class.. On Banquereau and Western Bank the indications are that the 1947 year-class will also give good recruitment to the fishery. Data are not available from St. Pierre Bank for the second quarter of 1951.

Haddock • Otter Trawl Haddock Catch 1«xi p. — Total Catch January to July • 60 --- Nova Scotia Offshore _ F-1 _ o El Large rn4 Scrod eH 1+0 D _ o - _ 10 o A ri N/ \1.--% --, _ ri 20 .\.«./, r .)--...... ."._. •ri ,..-- % 114111 _ o

_ o 1-1) Catch Per Trip you) 120 Trawlers o — Large o --Scrod g 5 co L k O 80

•o 40 .e 1 E-1 ■ \ ‘ \,. ,...... __...„_ ...... , 1.1. I...L.1...h, '25 30 135 140 145 50 1 1+7 848 01+9 150 151 Year Year Banquereau Western Bank St. Pierre II Quarter I Quarter II Quarter 1948 _J--- _ (40) (159) (120) _ 20 1. r- -ri o ,. 1949

0 ça. _ ei o C-) 20 (40) (354 ) (159) _ t8.0 - - 7 a) . 1950

o _ 1+é ri4 I 2C —1_ (12b) (280) (160) o 'ci 1951

_ If )

2 ) (40) (284) _ r- --4.-h- . ■ '' c0 co .0 4- ' c0 •C CO %/D CY O c0 co. ' -t- -1- ref rft -1- 4- -1-• -1- re, «1 -t- -t crl re-) Year Class These data show that a relatively small number of year-classes are represented in the haddock catch and that large fluctuations in year-class strength occur. For example, in 1948 to 1950 the haddock taken from St. Pierre Bank belong mainly to the 1942 year-class. During the same period the 1943 and 1944 year-classes were dominant in the haddock catch from Banquereau and .WesternBank. A summation of the available evidence indicates that the increased scrod haddock catch in 1951 shows a good recruitment of new year-classes which should result in a continuing abundance of medium-sized haddock to the fishery. Continued collection of special statistics of the groundfish fishery is required in order that fluctuations may be analyzed to give a basis for prediction of changes In abundance. F. D. McCracken and J. M. Stuart

Appendix No. 3 - WASTAGE OF SMALL HADDOCK Thé increased use of otter trawls on the banks off Nova Scotia and the recent formation of the International Commission for the Northwest Atlantic Fisheries increases the need for data on the portion of the catch discarded at sea as well as statistics of the landed catch. Such information is necessary in order to determine whether res- trictive measures, such as minimum mesh sizes for otter trawls, are desirable. Four sea trips have been made to date in 1951 and a comparison of the actual catch with the landed catch for haddock is shown in the accompanying figure. Random samples were taken at sea and weighted samples of the scrod and large haddock landings were taken for the same trip. On the basis of the cull it is assumed that all haddock 45 cm. and over are landed; the wharf sample was then adjusted so that a direct comparison can be made with the sea sample. The following table gives the percentage of the haddock catch discarded at sea by numbers and by weight for each of the four sea trips. - -

Haddock discarded at sea b Canadian trawlers - 1 Offshore Banks

March 14 and 17, 1951 Western Bank 30

June 21, 1951 150 Banquereau Middle Ground 120

to 496 July 19-26, 1951 (FA St. Pierre o Banquereau e, 150 Sable Island

e 120

90 60

61, 30

to 197 August 28 and 29, 1951 150 St. Pierre Bank

120

90 6o

J310 70 2ta Length - cm. -- Sea sample --Wharf sample -1+2 Percentage of the total catch of haddock discarded Month Banks Number Weight March* Western 21 27 June Banquereau and Middle Ground 56 37 July St. Pierre, Banquereau and Sable Is, 84 59 August St. Pierre 64 30 *March sampling somewhat inadequate for this purpose These data support the general knowledge that larger quantities of small haddock are taken during the summer months. Variation in the percentage of small haddock discarded, as shown by the summer trips, is presumably due to differences between banks but it is apparent that continued sampling is necessary before drawing definite conclusions. The bimodal characteristics of the catch curve with large quantities of haddock around 30 cm. in length being discarded may indicate production of a good year-class (see also Appendix 33) , F. D. McCracken

Appendix No. 35 DANISH SEINING COMMERCIAL TRIALS Fishing operations of a 39 ft. Danish semer (converted from a flounder dragger) have demonstrated that Danish seining for flatfish is.a profitable method of fish- ihg in Chedabucto Bay. In Danish seining an area of bottom is enclosed by two miles of rope and the seine. The ropes and seine are then hauled, the ropes sweeping bottom fish into a central path and into the net. Trials of this method of fishing, using the M. V. "J. J. Cowie" in the summers of 1948 and 1949, demonstrated good prospects of profitable commercial seining for flatfish in Chedabucto Bay. The Fisheries Research Board interested the owner of the M. B. "Gay Rover", a 39-ft. flounder dragger, in this method of fishing with the results of the "Cowie" trials. The gear used by the "Cowie" was loaned to him. Assistance was also given in installing the gear and making the first sets. Detailed records of his operations have been received in return (see table).

- - Semer landings, landed value, expenses and net profit Month Landings - lb. Value $ *Expenses $ Net $ May 42,000 1289.72 455.6o 834.12 June 66 l 000 1992.00 374.93 1617.07 July 80,000 2365.65 422.40 1943.25 August 101,000 3045.80 796.55 2249.25 to Sept. 9 31,000 1071.50 63.00 1008.50 TOTAL 320,000 9764.67 2112.48 7652.19 * includes mages paid to deck-hand For comparative purposes there are available spo- radic records from a 53-ft. dragger operating in Chedabucto Bay (see table). Catch per day fished, semer vs dragger Danish Semer Dragger Period Lb , per day No. of days Lb. per day No. of days May 25-31 4,654 4,195 3 , June 4,743 4,470 8 July 4,436 18 5,060 10 .Aug. 1-4 8,680 3 8,095 3 Cost of operation for the Danish semer is less than for the dragger (one less crew man and smaller running cost), thus in terms of net profit the seining method is even more favourable than in terms of poundage. It is of interest to note that practically no roundfish were taken by the Danish flounder seine and that witch (Glyptocephalus) made up- approximately 78 per cent' of his total catch. The grounds available for Danish seining are more restricted than for dragging since relatively smoother bottom is needed to prevent fouling. Indications are strong, however, thât on such grounds where concentrations of flatfish are sufficient to afford profitable small-boat dragging the Danish seining method is more efficient and profitable. F. D. McCracken

Appendix No. 36 EXPLORATORY DRAGGING AT THE HEAD OF THE BAY OF FUNDY Exploratory draggini's in 1949 by the Fisheries Research Board using the M. B. "Pandalus" resulted in the development of a fishery ftr the winter flounder (Pseudopleuronectes americanus) in western Minas Basin between Kingsport and Cape Blomidon and in Scotsman Bay. , Further exploration in 1951 at the head of the Bay of Fundy failed to extend the grounds now being fished. A survey of Minas Basin, Cobequid Bay, Minas Channel and Chignecto Bay was made with a 40-ft. flounder drag using the M. B. "Mallotus" during June and July. Irregular, hard and rocky bottom prevents dragging in eastern and central Minas Basin, Cobequid Bay and eastern Chignecto Bay. Elsewhere at the head of the Bay of Fundy dragging is possible but results indicate that only in the areas now being fished are commercial quantities of • either winter flounders or haddock available.

Size and age comDosition3 1949 vs 1951 In 1949 about 80% of the "Pandalus" catch of winter flounders were fish of over 12 inches (the minimum commercial size) and of these about 80% were seven years or older. In 1951, 62% of the winter flounders taken were larger than 12 inches and of these only about 10% are over six years of age. These data indicate that the accumulated stock of large old fish has been considerably reduced and are substantiated by the continued drop in catch per unit of effort from 1949 to 1951 (see also Appendix 38). Continu- ance of the fishery for winter flounders in Minas Basin will be largely dependent upon recruitment to existing stocks. L. M. Dickle

Appendix No , 37 EXPLORATORY DRAGGING IN THE SOUTHEASTERN GULF OF ST. LAWRENCE The M. B. "Mallotus" began exploratory dragging. for groundfish in this region by late August and this exploration was continuing at the time of writing. Drags were made with a 50-ft, flounder drag at stations in the Nor- thumberland Strait as far west as Wallace Harbour, N. S., in George Bay and from Cardigan Bay to East Point, P. E. I. Echo sounding of the bottom along the north shore of Prince Edward Island from East Point to North Rustico indicates that up to 10 miles offshore the bottom is rocky and not suitable for extensive dragging. Inside 20 fathoms on the northwest shore of Cape Breton Island similar conditions exist. Outside 20 fathoms only a few tows have been made and these produced negligible catches.

o HADDOCK ' HAKE 0 <25 lb. 0 0 0 <25 lb. 6•• s 0 0 o 0 25-100 lb. soMPI 0 0 25-100 lb. s.,, 0 )100 lb. 0 o 0 >100 lb. o 0 0 o 0 O P. E. L0 0 0 00 P. E. I. o m ..,) 0 0(D o ° 0 o /) -1_2 o 0 0 o 0 0 o o o o o c.e, o c. • e 0 00 o o , 0 0 o o 0 o 0 o t. 0 . • 0 0 a) 0 o I' o .i°3 r 0 0 o 0 o u O 0 0 (5. 0 0 Ce7ib te 0 0 0 Cp. 0 0 00

, N. S. WINTER FLOUNDER WITCH _e.e.t. • o 0 <25 lb. c..st -e ' o o 0 <25 lb. so,...,,,s o 0 0 25-100 lb. Seo.,, o 0 25-100 lb. o o )100 lb., o 0„ o 0 0 >100 lb. 0 00 o 0 o w P. E. I. c_ P. E. I. 0 O ID 0 0 0 °O 0 ../ o ...1 o ■ -1-- "\-- o 1-" _.- 7--‘11 ce 0 0 o ?I` 0 0 0 0 o o o C . e e)o- o c. w« o 0 0 0 o 0 O 0 o 0 0 0 0 e o 0 0 0 ri 0 0 , 0 0 n v esJ ° r 0 0 ". c :' 0 Ce o 0 0 6'«e' 0 „, o o e 0 -- 0 0 v v 0 0 0 0 0 Cf.' 0 0 2. u

N. S. . N. S. - . Approximate positions of half-hour tows in southern Gulf See legend for catches -46- In the other areas noted above half-hour tows were made at 61 stations. The principal species of groundfish taken were hake, haddock, witch and cod. Plaice and winter flounders were taken in many of the tows but only a small percentage were of commercial size. ; The best catches were made along the Prince Edward Island shore from East Point to Prim Point in depths of 15 to 21 fathoms. The position, depth and catch in pounds is shown in Table I for all catches over 100 lb 0 per half-hour tow. Table II gives the weight of each species in this total catch. Each circle on the accompanying figure represents the approximate position of a half-hour drag. Catches of haddock, hake, witch and winter flounders are shown as indicated by the accompanying legend. Table I Position Depth No. of Total Latitude N Longitude W fm. Tows Catch 45°40' 610451 12-14 1 150 45°52' 62°17' 15-16 1 233 45°56 1 62°20' 17-21 1 164 450 59' 620251 20 1 312 45°56' 62°28' 23-25 1 321 450 53' 6205o8 18 1 466 450528 620551 21-23 1 302 450548 630o31 19-20 1 202 46°17' 620 07' 21 1 376 46°13' 620 10' 18 1 193 46°16' 62°05' 22 2 870 460161 620oll 17 1 4o4 460191 61048' 24 1 207 460171 61°53' 20-22 1 180 TOTAL 4,380 Table II Species composition of total catch Species Weight - lb. Hake 1,870 Haddock 965 Witch 820 Cod ' 309 Plaice 295 Winter flounder 121 4,380 - It should be noted that hake made up almost half the total landings and were present in all catches of over 100 Ib. per half-hour tow. Hake are relatively cheap fish and are at present being at least partially discarded by the draggers operating in this region. Of,the flatfish species taken, the witch were all of commercial size. In deeper water (12 fm, or more) the winter flounders were of large average size but not numerous in any of the tows. In shoaler water of Northumberland Strait winter flounders were more numerous but a large proportion were below present commercial size. Plaice of commercial size were found only in the deeper water of the Souris region. Exploration is being continued through October and November to assess possible seasonal movements of the major species. The better catches of groundfish to date have been taken from grounds already fished by one dragger of the Gloucester type and by several larger draggers. Our data indicate that dragging could be extended further into the Northumberland Strait than is the case at present. In the region sampled, areas not already being fished by draggers do not appear to offer good prospects except on a limited basis. Completion of this survey and critical examination of the data obtained will indicate whether certain areas should be more thoroughly explored. L. M. Dickie

Appendix No. 38 DEVELOPMENT OF INSHORE-COMMERCIAL DRAGGING Inshore flounder dragging beginning'in 1948, on the basis of Fisheries Research Board exploration, included in 1951 tuo new areas and significant amounts of other species besides the winter flounder. Statistics of the fishery irkicate that further expansion can be anticipated only through discovery of new grounds. Detailed records of catch and effort are being obtained and this relatively new fishery is being followed closely, but: the wider scope of dragging operations increases the difficulty of obtaining precise comparable records.

St. Mary Bay A million pounds of winter flounders were landed from St. Mary Bay by Octo::.er, 1951, showing no increase over the same period for 1950. Thirty-two small draggers operated, at least periodically, as compared to 24 in 1950 - 1+8 - and approximately half the winter flounder landing was taken from a previously unfished region off Cape St. Mary. Haddock landings of half a million pounds and catfish landings of 125,000 lb. both show an increase. Age composition data for 1948 through 1951 show that a higher proportion of young winter flounders were taken in 1951. The 1941 year-class which made up 30 to 40% of the catch in April, 1950, has practically disappeared from the catch in 1951. In the early spring fishery the catch per unit of effort was much lower than in previous years but reduced - effort during the summer gave a higher catch per unit of effort than in 1950. The high catch per unit of effort and large average size of flounders on the Cape St. Mary ground suggest an It accumulated" stock. Tagging Winter flounders were tagged in St. Mary Bay in October and November, 1949, in May, 1950, and in October, 1950. The number tagged and the number of returns up to September 15, 1951, are given in the following table: Number Number Number Time of Number Recovered Recovered Recovered Tagging Tagged 1949 1950 1951 Oct.-Nov., 1949 2,616 114 499 94 May, 1950 1,523 512 161 Oct., 1950 2,009 232 162 The number of tags retaken indicates a relatively intensive fishery. All recoveries (with one doubtful exception) have come from the St. Mary Bay region. Only three tag returns from the Cape St. Mary ground in a total of 417 shows that this stock is relatively separate from the rest of the bay. Minas Basin Seven draggers operating in Minas Basin and Scots- man Bay from late May through July produced the same catch of winter flounders (approximately a third of a million pounds) as five draggers did in 1950. Catch per unit of effort in 1951 decreased to approximately two thirds that of 1950,

Samples of the catch in 1951 confirm those of 1950 in that a greater proportion of young fish were taken than in 1949. -49- Annapolis Basin -

Dragging was more sustained here during 1951 than in either 1949 or 1950. Nine draggers operated in 1951 and six of these for considerable periods of time. As a result the reported catch of winter flounders was approximately half a million pounds as compared to 120,000 lb. in 1950. Chedabucto Bay

Four small draggers operated in Chedabucto Bay in 1951 where none had operated previously. Explorations of the M. V. "J. J. Cowie" in this bay during 1948 and 1949 showed promising catches of flatfish. Stimulus to dragging in this area was also supplied by the success of the Danish semer (Appendix 35). The bulk of the catch consisted of flatfish (plaice, witch and winter flounders) which are species not exploited previously in this area. Expansion Significant expansion of the inshore flounder- dragging industry can only be anticipated through the discovery of new grounds and may require a lowering of the commercial size limit as set by the industry to utilize slower-growing flounders found in other parts of the Mari- times. F. D. McCracken - 50 {MD Appendix No. 39 LIFE HISTORY OF A FLATFISH TREMATODE Inshore dragging of winter flounders for human con-. in the Maritimes in 1948, and during 1949'some sumption began objections were raised by the industry to the presence of "cysts" on the fins and in the fillets. Investigation in 1950 and 1951 has shown that these cysts are caused by the metacercaria of the parasitic flatworm Stephanostomum histrix (Duj., 1945) Stafford, 1904, and that all species of flatfish in Maritime waters, except the halibut, are infected to some extent with this trematode. Such species as plaice, yellowtail and witch which occur on both inshore and offshore grounds show a higher infection among the inshore populations. Typical inshore species carrying the infection are the winter flounder, the smooth flounder and the brill. Particular emphasis has been placed on the occurrence of the cyst in the winter flounder which is the most heavily infected of any species. Sampling of winter flounders in 1951 shows the following incidence in relation to area:

Place Number of Fish Per cent Incidence Bras d'Or Lakes 450 2 Shippegan 35 0 Chedabucto Bay 40 28 Minas Basin 355 3 Annapolis Basin 331 65 St. Mary Bay 200 50-70 Passamaquoddy Bay 1,600 30-97 Small Point, Me. 33 50 Nantucket Point, Mass. 35 0 It is apparent that the highest incidence was found about the lower Bay of Fundy. This species of trematode occurs in Newfoundland waters and in the Gulf of St. Lawrence. Samples of European plaice indicate that the same species of trematode occurs in European waters. The worm Is limited in its distribution to the riorth Atlantic. In Canadian waters the major definitive host is the sea raven, which has a wide distribution. Specimens of the adult worm have been taken in the rectum of the fish, in from 5 to 120 fathoms both inshore and offshore. Other definitive hosts reported are:. arctic eelpout, halibut, wrymouth; one large short-horned sculpin was collected in - 51 - Passamaquoddy Bay with a light rectal infection. Attempts to infect cod and haddock artificially were unsuccessful. The family Acanthocolpidae, to which this trematode belongs, has molluscan hosts for the primary stages of its life history, specifically gastropods. Examination of about 3,500 molluscs has shown no presence of the redial or cercarial stages of St. histrix. The largest part of this collection consists of snails but bivalves were collected, when plentiful, from areas of heaviest infection. The major portion of the collection has been inter-tidal since collections of large numbers of molluscs below low water have proven difficult. Any continued study of the trematode life history should emphasize examination of the invertebrate species in infected areas and the co-ordinated following of the hatching of small flounders and the first signs of infection. Small flounders (3-7 cm.) representing this spring's hatching rere found infected during the month of August. Later examination, both of fish and metacercariae, suggest that'peak cercarial shedding may be reached at about this time. Monthly collections of flounders in Passamaquoddy Bay showed no marked seasonal variation in Incidence for commercial-sized fish. All available evidence points to external pene- tration as the method of infection. Progressive infection from year to year is also indicated. No pathogenic effects could be demonstrated in flounders and the cyst apparently lives as long as the flounder. Cysts of Stephanostomum histrix will not develop In mammals and are thus not harmful to them. Present evidence indicates that normal infections of the parasite are no longer considered a serious \-objection to the marketing of. flounder fillets. While the primary host for the trematode has not yet been determined, it appears unlikely that control of the infectiqn by interruption of the life-cycle will be feasible. The major definitive host is widely dispersed and it seems likely that the primary host will be also. The difficulties involved in any attempted control are obvious. Care in handling of fillets, discarding those which have heavy infections, appears to be the only practical solution to marketing difficulties. R. W. Wolfgang

-52 61. Appendix No. 40 LIFE CYCLE AND CONTROL OF THE COD-WORM Adult cod-worms have been collected from the stomachs of harbour, gray and harp seals but the first stage in the life cycle of the cod-worm has not yet been determined. The cod-worm investigation during 1951 has had two phases: (1) determination of the worm infestation in an isolated area so that the effect of a seal control pro-. gram (reduction in numbers) can be evaluated, and (2) discovery of the first stage in the life cycle of the worm. Phase 1. Examination of small, young cod was continued in the Bras d'Or Lakes during 1951 with the number of fishing stations reduced from five to three. Location of these stations is shown in the accompanying map. The advantages of the Bras d'Or Lakes for this program are as previously stated in 1950. Infestation data for 1950 and 1951 is compared in the following table: Worm infestation* of cod from three stations In the Bras d'Or Lakes in 1950 and 1951

Age Baddeck Bay Kempt Head Whycocomagh Bay Group 1951 1950 1951 1950 1951 1950

I 1.7 2.3 40o 5.4 0.1 0 0 1 11 11.1 11.0 8.3 8.3 0.2 0.3 III 18.2 9.7 13.2 16.0 0.3 _ IV 12.3 11.9 13.0 14.6 0.5 0.5

V. 21.2 15.2 20.5 16.8 1.8 1.3 *Average number of worms per fish

Whycocomagh Bay remains the area of low infestation, while Baddeck Bay and Kempt Head are areas of high infestation. Cod of the same age and from the same station show comparable infestations for the two years, particularly in the younger ages. The scarcity of the 1947 year- class in the 1950 sample seems to account for the dis- crepancies between three-year-old fish. Growth rate studies in 1951 tend to support the hypothesis that young cod in Bras d'Or Lakes are divided into local populations. The length and worm infestation of two-year-old fish fcr both years' samplings are shown on the accompanying map. While minor differences are apparent in the results of the two years' samplings it eLittle Narrows Whycoco- Grand magh Narrows Day ,

Bras D'Or Lake

0 5 Scale in miles

Bras D'Or Lakes. Mean length (cm.) and. worm incidence for age group II cod in 1950 and 1951 ; • - • . e 2. g •

- 54 - appears that the data are stable enough to provide a base line for evaluating the effects of a seal control program. If ice conditions permit, it is expected that attempts to reduce the numbers of seals or to drive them from this section of the lakes will be made in 1951-52. Phase 2. Considering the available evidence, the most logical hypothesis is that cod-worm eggs passed in the faeces of seals are ingested by an invertebrate which serves as a primary host in the life cycle of the cod- worM. Sampling of invertebrates during the summer of 1951 in Bras d'Or Lakes shows that starfishes, bivalves, Dolychaetes, amphipods and mysids are commonly found, while sponges, sea anemones, sea urchins and shrimp were found- in localized areas. Identification of species and their examination for nematodes will be carried out during 1951- 52. Mysids, polychaetes and gammerids were the commonest food of cod taken in Baddeck Bay and Kempt Head. In Whycocomagh Bay polychaetes and gammerids were common food of cod but mysids were much less important. Lack of mysids in the cod stomachs taken in Whycocomagh Bay, an area of low infection, gives a possible lead to the invertebrate primary host of the cod-worm. Attempts are being made to hold small relatively uninfected cod transported from Whycocomagh Bay to Baddeck Bay for artificial infection experiments. Once nematodes have been found in an invertebrate or invertebrates, artificial infection by feeding these to cod will be necessary in order to prove transmission of the worm and its identity. Summary of W. F. Black's report by F. D. McCracken

Appendix No. 41 EXPLORATORY DRIFT-NET FISHING FOR HERRING Drift-net fishing for herring was undertaken during the 1950 season in three areas along the.Atlantic coast and the results obtained in one of them, viz, the southwestern portion of the Gulf of St. Lawrence, were very promising. Large catches of both herring and mackerel were made regularly at most of the fishing stations within the area and the average catches per net were equal to or better than commercial catches in the North Sea. This was the first successful attempt to catch herring in offshore - 55 - areas although searching with echo-sounders and various gears such as purse seine, otter trawl, Dutch herring trawl and floating trawl had been carried on for.several seasons. During the 1951 season this exploratory drift- netting was continued and was confined for the most part to the southwestern Gulf where large quantities of herring

OrCR.*, saler Nei srAnows mi. at. COVOE 5 had been taken in 1950. However, one cruise was made along the outer coast of Nova Scotia and one in Fortune Bay on the south coast of Newfoundland. The accompanying chart shows the location of the stations which were occupied. In brief, the program for 1951 was as follows: a fleet of gill-nets, approximately 375 yards long and 8 yards deep was fished at 20 stations, of which 13 were in the Gulf of St. Lawrence and the remainder on the outer coast of Nova Scotia and on the south coast of New- foundland. Five sizes of nets were used, viz. 2", 2f", 2-1", 2t" and 3" stretched mesh. Two nets of each mesh size, or a total of ten units, made up the fleet. The fishing was done chiefly from the M. V. "J. J. Cowie" and 34 sets were made from this boat during the season. The M. V. "Harengus", which was made available by the Depart- ment of Fisheries, occupied two stations in the Gaspé area during the latter part of August using 10 nets all of 2" mesh. Fishing was done at night as in 1950 with the nets being set before sunset and hauled back immediately after daybreak. Plankton hauls were made before each set and bathythermograph recordings taken before and after each set. A detailed record of atmospheric conditions was made every hour while the nets were in the rater. Catches were kept separate according to species and mesh sizes and were measured in bushel baskets or counted if the quantity was too small to measure.

The catches during the 1951 season were generally poor. The total amount of mackerel (8575 lb.) was slightly higher than last year (8000 ib.) but there were seven more fishing days this year. The average catch of herring, however, was only about one tenth as large as in 1950. The total catch of herring at the stations in the Gulf of St. Lawrence was 4000 lb. for 29 fishing days using 10 nets, whereas last year nearly 36,000 lb. of herring were caught with 12 nets in 22 fishing days. At each of four stations last year more herring were caught In a single night's fishing than were caught altogether this year. The accompanying table gives a summary of the total catches of herring and mackerel by areas together with the average catch per set within those areas and the most effective mesh size. The factors responsible for the failure to capture herring in quantity this year are not known. The overall distribution of herring and their reactions to various environmental conditions are still only vaguely understood and prediction of distribution and abundance is impossible. In addition to this, the suitability of the gear which we have been using to catch herring in offshore areas has not been well established even though good catches were made last year. In fact, it Is considered much more likely that it was the gear which was at fault rather than that there was any great difference in the distribution and abundance of fish. • A number of observations on the operation of drift-nets for the two seasons are noted and some suggestions included which might explain the differences in catches. 1. In both years the nets were fished at the surface only. No provision was made for increasing the depth at which they were set. Except as noted below, herring could only be caught if they were within twenty- four feet of the surface. Throughout the season surface temperatures at the fishing stations were slightly higher in 1951 than they were the previous year. This may have had the effect of keeping the fish deeper in the water where they could not be reached by the nets. 2. Towards the end of the 1951 season double depth nets (i.e. 48 feet) were rigged and caught herring

DRIFT-NET CATCHES OF HERRING AND MACKEREL IN 1952 No. Total catch AvocatCh per set Most Station of .(pounds) (Pounds) effective Number Locality Dates sets Herring Mackerel Herring Mackerel mesh size HDN 23-, 12 Outer coast of . and 25 Nova Scotia May 11-19 3 200 0 67 2*" HDN 33, 34, Fortune Bay, .35 and 37 Newfoundland May 29-June 6 4 550 0 138 2im

HDN 1, 28, Prince Edward June* 12-18 and 26 Island East July 4-5 2*"(mackerel) Aug. 13-24 9 1500 2550 167 283 2e(herring).

HDN 2, 3 Magdalen June 19-26 2" (herring) .and 27 Islands August,20 300 950 60 190 2" (mackerel) HDN 6, 3b Prince Edward July 10-14, 25 .and 4 Island West August 6 and 7 - 2" (mackerel) August 27-30 7 450 2050 75 342 2" (herring)_

HDN 31 Chaleur Bay July 16-17 September 4 Sept. 13'-14 3 0 1800 0 600 2" - 3" HDN 5 1 7 American,Orphan July 18 and 19 and 8 and Brade 11e August 28-30 2"x2e(mack0) Banks Sept. 10-12 5 1750 1225 350 245 2'1 (herring) TOTALS 36 4750 8575 136 245 - 58 and mackerel in quantities which were equivalent to the best catches in 1950. These nets were used only on three occasions and it is therefore impossible to state whether or not deep nets would have taken larger quantities throughout the period. It may be noted, however, that at Station EDN 31 on September 3 two deep nets of Ze and 2tu mesh caught 375 lb. of herring and mackerel while four shallow nets of the same size took 250 ib., or on the average only one third as much. On September 10 one 2-iu deep net took 300 lb. of herring while two shallow nets of the same mesh size took no fish. On September 11 at - Station HDN 8 two 2in shallow nets caught only 3 fish while one 2e deep net caught 2-b bushel baskets of mackerel (ca: 310 lb.). 3. In 1950 all the nets were weighted with either leads or small stones attached to the foot ropes but this was not done generally in 1951. Experimenting with this feature it was found that weighting alternate nets within the fleet made no difference whatsoever to the catches but the leaded nets were more apt to foul than the unleaded ones. 4. Although the overall production of planktonic organisms on which herring feed was not noticeably different in the two seasons, large quantities of them were taken about two weeks earlier in 1951. Since fishing started two weeks later in the Gulf this year it is considered likely that a full month of the best fishing was lost. This, however, does not explain why the catches were small throughout the season. The comparatively poor results of drift-net fishing for herring during 1951 were very disappointing but the season's operations should not be considered to have been a total loss. Much valuable experience in the handling of drift-nets was gained and data collected on temperature variations, abundance and distribution of plankton, the selective action of gill-nets of various mesh sizes and the most effective mesh size to use in different areas. In addition, samples of herring were obtained for average sizes, development of the gonads and fat contents. It seems obvious that for successful commercial use a greater depth of net is required and also that the nets be rigged so that the depth at which they are set can be adjusted readily. Plans are being made to continue this investigation next year and drift-nets such as are used in the North' Ses::: Nill be made available. Less effort will be spent in widespread exploration and more attention will be given to the vertical distribution of the herring in relation to temperature, feeding and light conditions. S. N. Tibbo and E. G. Sollows - 59 - Appendix No. 42

• FISHING EXPERIMENT WITH A PELAGIC TRAWL In the previous two Annual Reports of the Atlantic Biological Station references have been made to experiments with a herring trawl designed and constructed by Robert Larsen of Skagen, Denmark (Appendix 40, 1949, and Appendix . 36, 1950). These reports included a description of the trawl, the methods of handling and a summary of the results obtained. Some difficulties were experienced in handling the gear and the net was torn very frequently. This may have been due to (a) too great a difference between the size and power of the pair of boats using a net, (h) lack of experience on the part of the crews, or (c) the net not being strong enough to withstand the strains placed on it. Small quantities of herring were taken on many occasions and it was felt that further trials were warranted. In the spring of 1951 Captain Allison MacDonald of Loggieville, N. Bo, requested assistance in modifying a groundfish trawl to catch herring. This was believed to be difficult, if not impossible, and as an alternative Captain MacDonald was loaned early in May two small Larsen trawls (36 feet) in exchange for a complete set of records on their operation and the quantities of herring caught. Captain L. J. Lewis, formerly of the M. V. "Harengus", was on board one of the boats as an observer during the three days that the nets were fished. The results of the experiment, together with some observations on the working of the gear, are noted as follows: 1. The two boats used - the dragger "Gloucester No. 22" and the tug "Atwood" - were very evenly matched. They were both about 60 feet long and were powered with identical engines: D13000 model Caterpillar Diesels rated at 100 h.p. at full speed. The crews were all experienced fishermen. 2. After four practice sets which were made on May 5, actual fishing was begun on May 7. The older trawl was used six times before it was so badly torn that It was not worth repairing. After four of the six tows some repairs had to be made. A total catch of 6i bbl. (ca. 1950 lb.) of herring were landed.

3 0 Eight hauls were made on May 8 using a newer trawl. This trawl was torn six times and a total of 38 bbl. (ca. 11,400 lb.) of herring were landed. 4. In all, 40 man-hours were required during the two fishing days to keep the nets in repair and in addition one net was almost completely ruined. -60- 5. Considering the fact that the trawl was torn six out of the seven times that some herring were caught, and that fish were seen escaping each time the net was torn, the total catch of 14Ff bbl0 was good. 6. The length of the tows varied from 10 to 50 minutes and at least 20 such hauls could be made each day if no repairs were necessary. The best landed catch (16 bbl.) was made in a 10-minute tow. 7. Both Captain MacDonald and Captain Lewis estimated that there were at least 50 bbl. of herring in one 35- minute tow on May 7 0 All but 6 bbl. of these were lost when the net burst after part of it had been taken on board. In spite of the high cost of operating this net due to the necessity of using two boats with a total crew of 9 or 10, it appears that the method would be well worthwhile if the net was strong enough to withstand the strains of the fish that were caught. Further work is planned using a net of heavier twine and larger mesh sizes, and also with a smaller net in the Bay of Fundy area for sardines. S. N. Tibbo

Appendix No. 43 HERRING POPULATION STUDIES In 1944 the Atlantic Herring Investigation Com- mittee began a study of the herring along the Atlantic coast of Canada to obtain information on the general life history including such aspects as reproduction, age, growth and migrations, and to determine by biometrical analyses whether all of these herring- belonged to a single population or if two or more groups could be recognized. Some very striking differences were observed in the data from the various localities and it therefore became obvious that there were separate groups of herring which intermingled to a limited extent, if at all. This intensive study was concluded in 1949. Subsequent work by the Atlantic Herring Investigation Committee up until its dissolution early in 1950, and continued since then by the Atlantic Biological Station, has been of a routine nature. Small samples of the commercial catches have been obtained annually from six localities which are considered to have distinct populations. These have been collected to follow changes in length, age and year-class composition, and also to test the constancy of those characters, such as vertebral and fin ray counts, which are different for each group. The accompanying figure shows the length and age composition of herring samples taken from areas which have - 61 - separate populations and the differences between the samples are apparent. One of the most striking features is the large number of year classes which are represented in most of the areas. This indicates a low mortality rate for adult herring and suggests that an increase in the fishing effort would not be apt to do more than remove a larger portion of this accumulated stock of old fish. This should be beneficial to the population as a whole since the rate of growth declines sharply after sexual maturity in the fourth to the seventh year.

CARACHJET NS.

" MONTH RUSTIC 0 P.C.I.

r ir

LUNCNSURG N. S.

FORTUNE RAT NFLD.

TOTAL LCNG TN CY* • EAR CLASSES

Length and age composition of herring samples from six major population areas

Another important feature illustrated in the figure is the relative strength of the year classes. The 1941 and 1943 year classes were particularly abundant in . the catches at most of the Gulf of St. Lawrence ports from 1946 to 1949, in most cases contributing 60% or more of e _I

- 62 - the total catch. The implication here is that several poor year classes in succession could seriously reduce the overall abundance of herring in these areas. Any attempts at predicting the availability of herring from year to year would have to take this into consideration. A study is needed of the factors which determine the relative success or failure of the various spawnings. Apart from the actual collection of data, most of the effort expended on studying the biology of the herring during the past year has been directed towards the preparation for publication of the results of the investigation carried on by the Atlantic Herring Investigation Committee during the period 1944 to 19490 A final report of this study is expected to be complete early in 1952. During the 191 season routine samples were obtained from Lunenburg, N. S., Caraquet, N. B., Matane, P. Q., and Fortune Bay, Nfld. Altogether, 11 samples consisting of 1210 individual herring were examined for lengths, ages, sex and maturity of the gonads, abdominal and total vertebral counts and pectoral fin-ray counts. In addition to this the exploratory drift-net catches during the period May 10 to September 14 provided an additional 21 samples consisting of 2337 herring. These were examined for lengths only to determine the average sizes at the various fishing stations and to get some indication of the extent of gill-net selection. These data have not been fully examined as yet and hence no report can be made on the results. S. N. Tibbo

Appendix No. 44 HYDROGRAPHIC AND PLANKTON INVESTIGATIONS The study of temperature conditions and the abundance of food in relation to drift-net catches of herring was continued during the 1951 season. Hvdrographv In co-operation with Dr. Lauzier, bathythermograph observations were made regularly at the fishing stations and in addition some observations were made at approximately eight-mile intervals while the vessel ras proceeding from port to a fishing station or from one fishing station to another. Two sets of fairly continuous observations were included across the Laurentian Channel between Sydney, N. S., and St. Pierre, and along the Gaspé coast. The data are being analyzed by Dr. Lauzler. A cursory inspection of the records shows that surface water temperatures were slightly higher in the Gulf of St. Lawrence in 1951 than in 1950; the average at all fishing stations for July and August was 16.6°C. in 1951 as compared with 15.5°C. in 1950. Whether or not this condition was general throughout the area is not known and will have to await a more careful examina- - tion of these and other temperature records. It is possible that the smaller catches of herring and mackerel in 1951 were the result of higher surface water temperatures asso-, ciated with the shallowness of the nets used. However, very little is known of the relationship between water temperatures and the distribution of herring and more extensive studies on this and other limiting.factors are planned for next year. Plankton Plankton samples were taken immediately before or after setting the nets at each station. In all cases 10- minute horizontal tows were made at approximately 3 metres below the surface. The net had a circular opening one metre in diameter and was made of a cloth with from 12 to 15 meshes to the centimetre. There appears to be very little difference in the composition of the plankton tows during the tso seasons. The copepod, Calanus, was again the principal constituent with smaller and varying amounts of fish eggs, Ctenophores and Chaetognaths, Amphipods, Decapod larvae and fish larvae. However, large amounts (up to ko c.c0 per tow) of Calanus were taken in the tows about two weeks earlier in 1951 than in 1950 and continued to be very abundant for approximately two months - the same length of time as in 1950© - The relationship between the abundance of plankton and the quantities of herring and mackerel captured in , drift-nets which was apparent in 1950 was not in evidence during the past season when catches were generally poor re- galkiless of the amount of food present in the water. Further studies of the quantities and distribution of plankton are planned for next year and particularly to get a meature of the abundance at various depths and under different light conditions. S. N. Tibbo

Appendix No. 45 VARIATIONS IN THE CONDITION OF HERRING IN THE GULF OF ST. LAWRENCE The sampling of herring for fat determinations to be used as a measure of the condition of the fish was continued during the 1951 season. Samples were obtained from drift-net catches throughout the period May 1 to September 15. . -64- The usual procedure was to take six herring from each 10- centimetre group and after grinding and mixing thoroughly to measure small quantities in duplicate into a container with a known amount of Na2SO4. These samples were then sent to St. Andrews and fat determinations made by the ether extraction method. The values are expressed as a percentage of the wet weight of the whole fish. A summary of the results is given in the following table which shows the range and the average fat content by two-week periods throughout the season.

Percentage fat . - Fat content No. of Size Range Average Period samples (cm.) __I__ % May 1-15 4 23-33 6.1 - 10.7 8.5 May 16-31 8 27-40 7 0 6 - 13.1 10.8 June 1-15 6 25-39 7 0 9 - 18.8 13.9 June 16-30 3 25-35 11.1 - 20.7 16.8 July 1-15 6 17-40 9.5 - 15.8 13.5 July 16-31 4 28-37 13.4 - 20.6 16.7 Aug. 1-15 2 23-28 14.3 - 14.8 14.6 Aug. 16-31 10 27-40 8.6 - 21.3 14.9 Sept. 1-15 6 27-38 8.8 - 11.7 10.3 The results of sampling for fat contents during the 1950 season showed that there was both a seasonal and a size variation in condition. The large herring (30-40 cm.) were of the best quality, reaching a maximum fat content of nearly 20% by the end of July but not maintaining this condition beyond the early part of September when the gonads begin to develop. Small herring (20-25 cm.) were not particularly fat at any time, while immature fish (25-30 cm.) were .of excellent quality by mid-July (15%-18%) and held this condition at least until September 15 when the sampling was concluded. Plans were made to check these results during the 1951 season but owing to the fact that very few of the small and immature sizes were taken it is felt that the samples of these groups are too small to be very reliable. For the whole period (May 1 to September 15), however, small herring (20-25 cm.) averaged 10.2%, immature herring (25-30 cm.) averaged 12.3% and large herring (30-40 cm.) averaged 13.2% fat. These results are in general agreement with the results obtained in 1950. The 1951 results as shown in the table indicate that herring recover rapidly from the effects of spawning and of low water temperatures and are in good condition by the middle of June. The table shows further that this high fat content is maintained throughout the summer months. S. N. Tibbo and P. J. Gibson Appendix No. 46

BAY OF FUNDY SARDINE INVESTIGATIONS No consistent study of Bay of Fundy sardines has been attempted this year but a few samples were obtained to follow changes in the size composition of the catch from Charlotte County, New Brunswick, to check variations in condition (fatness) throughout the season and to keep informed on the incidence of the fungus disease which sometimes affects a large portion of the population. - Altogether, five samples totalling 1,251 fish were obtained. Two samples in September indicated a normal recruitment of small fish (ay. size 11.78 cm., 1950 year class). The three samples taken in July and August were of large sardines (ay. size 22.96 cm.) and this suggests that the 1949 year class which appeared normally in September, 1950, was absent from the 1951 catches. Only four samples were taken for fat determinations. These showed a variation of from 7 0 3% to 17.4% fat content which is normal for this area. Fat determinations were made by the ether extraction method and are expressed as percentages of the wet weight of the whole fish. There were evidences of the herring disease which is caused by Ichthvosporldium but the condition was not serious in 1951. The highest percentage of infected fish was 2.03% in a sample taken on September 18. S. N, Tibbo and P. J. Gibson

Appendix No. 47 TUNA (THUNNUS THYNNUS) IN CANADIAN ATLANTIC WATERS The tuna fishery of the Canadian Atlantic coast reached maximum production heights of 1,700,000 and 1,600,000 pounds in 1946 and 1947 respectively. Production has since declined through 800,000 pounds in 1950 to a post-war low of about 400,000 pounds in 1951. Observations made and data collected during visits in September and October to the St. Margaret Bay commercial fishery and the Wedgeport sport fishery revealed that the 1951 fishery was characterized by the non-appearance of the normal heavy run of the small "jumper" tuna during September and October. As a conse- quence the fishery in both areas has been made up almost entirely of the larger "albacore" tuna. The situation was particularly revealing in the St. Margaret Bay fishery where in 1950 the average round weight of tuna sampled over the season was 163 pounds while in 1951 it was 348 pounds. The collection of weight, length and age data will continue in

_ - 66 - 1952 in order to be able to recognize and perhaps explain possible changes in the composition of the stocks of tuna in our waters. Lure trials Despite the negative results of 1949 and 1950, tuna lures or jigs were trolled in and about St. Margaret Bay for two successive half days in early September but no strikes were recorded nor fish seen. It is hoped that, in addition to further lure trials, other possible methods such as surface line trawl and gill netting may be tried for tuna both inside and outside St. Margaret Bay in 1952 0 LenL th-I._velations21.12 Data collected this season and presented in tabular form below extends the size range and Improves the reliability of the relationship between fork length, round weight and dressed weight of tuna. Fork-length* Av. dressed Av. round Conversion groups No. of weight weight factor dressed (in,) fish (lb.) _010) to round weights Less than 45 8 35.1 44. 5 x 1.26 45-50 8 47.0 7200 X 1.26 50-55 6 70.7 89.7 X 1.27 55-60 12 94.4 115.3 X 1.22 60-65 13 119.0 144.0 X 1.21

fil••••11 95-105 2 505.0 612.0 X 1.21 *Fork length is the distance from the tip of the upper jaw to the fork of the tail measured along the curve of the body.

In addition, conversion factors have been established from 20 "jumper" size tuna for the following length relationships: Fork length (straight line measurement) to fork length (curved measurement) x 1.04 Fork length (straight line measurement) to total length (straight line measurement) x 1.08 Collections of various length and weight measurements will be continued in order to improve the above relationships and make our data comparable with that of other investigators. Age of "Jumper" tuna - Scale samples taken from "jumper" tuna captured in the St. Margaret Bay trap-net fishery during the first two weeks in October of 1950 were impressed on celluloid and examined to obtain age estimates of the "jumper" stocks.

- Age - Range of Av 0 dressed Converted estimate No. of dressed weight weight round weight (vrs.) fish ' (lb.) (lb.) (lb.) 11 29-48 36.4 4q04 e 23 53°73 61.2 77.1 5+ 39 - 64-90 78.5 98.9 6+ . 12 . 81-100 89.0 112.1 The above data show that "jumper" size tuna ranging from 29 to 100 pounds dressed weight are in their fourth to seventh years of life and suggest that the largest "jumper" (150 pounds dressed weight) might be in its ninth or tenth year of life. Since scales from tuna which are past their seventh e year of life are difficult to interpret, collections of vertebrae and other bony parts are being made and will be examined for clear growth lines. Preliminary examination has shown that age estimates from scales and vertebrae from the smaller "jumpers" agree. International co-ordination of tuna research At the Bermuda Oceanic Fisheries Conference held at the Bermuda Biological Station from May 23 to 31, which the writer was privileged to attend, an informal committee made up of members from the United States Fish and Wildlife Sèr- vice, Woods Hole Oceanographic Institute, University of Miami Marine Laboratory and the Fisheries Research Board of Canada, was set up to co-ordinate the research on tunas in the western North Atlantic Ocean. Duties included guidance of research on life history, movements and abundance of tuna, the standardization of measurements and sampling techniques, and the publicizing of the tagging of bluefin tuna by marked hooks at Bimini Island early in 1951. - Every effort has been and will be made to act in accordance with the aims of the committee in furthering our knowledge of the tuna in western North Atlantic waters. To this end various weights and lengths, scales and statistics have been collected from the tuna fishery off the Nova Scotia coast. To date no tagged hooks have been recovered in Canadian or American waters. It is hoped that next year tagging, which was limited to 50 marked hooks released at -68- Bimini in 1951, may be intensified. The possibility of tagging in Canadian waters will be explored. L. R. Day

Appendix No , 48 STREAM CLEARANCE FOR SPAWNING SMELT It has been shown that the clearing of minor obstructions from brooks tributary to the Miramichi can roughly double the spawning area used, permit the smelt to spread their eggs over a wider area and thus Increase the hatch. In addition it can.save many adult fish from being trapped above obstructions when the water level drops after the spring freshets. New developments in this field in 1951 are summarized below. During the autumn of 1950 a very great freshet occurred. Not only did the storm blow trees down into the streams causing initial obstructions, but the high water levels carried more debris to these spots and many complete barriers resulted. In addition, the heavy freshet produced new gravel bars and channels that proved in many places impassable to the spawning smelt in the spring of 1951. All this occurred late in the season and it was not possible to do any clearing before winter, an early spring in 1951 did not permit any stream improvement before the smelt were in the brooks. As a result in many brooks the smelt were unable to go nearly as far as in other years and much crowding occurred. There is no doubt that this was responsible in some degree for the much lower larval production in 1951 than in 1950. Spawning smelt were of average or greater abundance and in those tributaries which were not obstructed went upstream considerable distances, some new records being set as, for instance, at the Northwest Miramichi salmon trap where smelt have not been seen for many years. The run of smelt into Indiantown Brook was not nearly as large as in some years, but some of them did enter the new experimental "smeltway" built by the Department of Fisheries in 1950. They went up through the box section and part way up the baffle section but no further. At this point the water was quite swift and some re-arrangement or additional baffling appears necessary. At the same time more than half the smelt that reached the falls went past the entrance to the "smeltway" and lay for some time in the pool below the falls as formerly. Some sort of guide to the entrance seems needed. - 69 - - In Wilson Brook, where an experimental detour around an old log jam on sharply rising ground was prepared last autumn, good bodies of smelt negotiated this section of the stream, going on up as far as an old dam. A small hole has been cut through this to see if the smelt will go through and on up the fast water immediately above. If they are successful, proper clearance jobs should be done at these two points and on a good stretch of the excellent spawning brook farther up. Highways parallel the parts of the Miramichi where smelt spawn and each stream passes through a culvert or bridge not far above its junction with the river. Practically all rePaired or new culverts are such that smelt cannot pass through them. This problem should be discussed with highway authorities to establish a policy which will avoid unnecessary obstructions. Experience is being accumulated on which to base an assessment of the degree of obstruction or speed of water which will prevent the ascent of spawning smelt and which will point to remedial measures. R. A. McKenzie

Appendix No. 49

NUMBERS OF SPAWNING SMELT AND NUMBERS OF LARVAE PRODUCED Observations have been made over a number of years in an attempt to determine the relationship between the numbers of spawners and of larvae produced under varying conditions in the spawning areas. . Visual estimation, though difficult and inaccurate, appears to be the only method of assessing the , size of the spawning runs in the four main branches of the Miramichi River. Systematic fishing of a number of typical brooks provides information of a more definite character, however, on the runsein the brooks. Plankton collections at regular points on some of the tributaries, as well as at Newcastle bridge on the tidal part of the main river, provide information year by year on relative numbers of larvae. In the table it is seen that the numbers of spawners in the brooks and in three out of four of the main branches of the river were as great in 1951 as in 1950, or slightly greater, yet the larval collections were on a par with 1948 and much lower than the big production in 1950, being only about one tenth at Newcastle bridge and one sixth for the collections as a whole. -70- Visual estimation Total catch Total Total larvae of spawning run in systematic larvae collected main river branches fishing of collected from 6 points spawning Newcastle including NW LSW SW Renoua brooks bridge Newcastle bridge 1948 v.good v.good v.good 652 8 9 240 24 9 603 1949 good fair-poor 1,028 25 9 483 58,077 1950 good fair fair 1,118 68,793 132,829 1951 v.good v.good poor 1 9 145 7,3 85 22,899 With the spawning population in 1951 about on a par with that in 1950 9 some cause other than numbers of spawners must be responsible for the tremendous difference in larval production. In 1950 the rainfall in April was about average, while that in May was the lowest since records started in 1895. On the other hand, April, 1951 9 set a new high record and May was about average. In 1950 spawning began early in May and continued throughout the month without interruption due to freshets and the eggs were all deposited in the main channels and remained covered with water until hatched. In 1951 spawning in the headwaters began in the third week of April l lasting into early May. However, in some instances high water held the smelt down near the head of tide for most of their spawning and in others forced them out onto flooded flats which went dry later. Only In the Southwest Miramichi where the run was very good did the fish move up as far as usual. Because of the generally steep banks in that spawning region 9, little spawn was left dry as the water receded even though the fish spawned along the edge of the stream. The larval production in this stream was greater than in 1950 - an exception to the 1951 general pattern. Many of the smaller streams were so obstructed in various ways by the very heavy freshet late in the autumn of .1950 (see Appendix 48) that the spawning smelt were held back completely or able to ascend in only limited numbers. The low production of larvae in 1951 may be explained partly by the spawning smelt being held back by high water or obstructions, or by spawning taking place where eggs were later dried out. Extremes in precipitation during the smelt spawning season appear thus to have a strong effect on the number of larvae produced. R. A. McKenzie -71- Appendix No. 50 CATCHES OF SMELT YEAR CLASSES IN RELATION TO THEIR ABUNDANCE AS LARVAE Determination of the degree of correlation between - the total commercial take from% year class and its abundance as larvae will permit assessments both of the possibility of . predicting the abundance of commercial smelt by sampling larvae and of the probable effects of increasing production of - larvae by such means as stream clearance. We have already shorn that other factors than numbers of parents cause great Variations in the numbers of larvae (Appendix 49) and that stream clearance increases their numbers (earlier reports). Since developing the technique of estimating the ages of smelts from their scales, samples of commercial catches are being examined to determine the proportions of various ages in each year's catch in the Miramichi area. These data, combined with the thorough statistics available on the total catch, will give us the total commercial take from each year class for comparison with the relative abundance of its larvae as indicated by - regular plankton sampling. So far the age composition of the catch has been worked out for only three - fishing seasons (1948-49, 1949-50, 1950-51) and the total yield of only one year class (1947) estimated. A preliminary summary of the results is given in the table. Miramichi Smelt Catches in Pounds

• Fishing Seasons Year . classes 1948-49 1949-50' 1950-51 Total

1945 71,160 (4-) 71,160 + 1946 1,073,350 (3-) 46,170 (4-) 1,119,520 + 1947 868,790 (2-) 377,070 (3-) 214 9 200 (4-) 1,1+60,060± 1948 e 754,260 (2-) 737,220 (3-) 1,491;480 + • 1949 1 ) 226, 580 (2-) 1,226 9 580 +

Fish approaching two, three and four years of age usually make up almost all the commercial catch with very few older smelt preseht. Any one year class makes a substantial contribution to the fishery for only three years, usually playing its major role when it first enters the fishery as it approaches two years of age. The 1946 year class yielded over a million pounds when approaching three and four years of age in 1948-49 and 1949-50 and its total contribution was doubtless much greater. The 1947 year class in its three important years yielded a - 72 - total of about a million and a half pounds. The 1948 year class yielded about the same in its first two years in the fishery alone and the 1949 year class shows even greater promise, having contributed about a million and a quarter pounds in its first year. The 1949 year class was about three times as abundant as the 1948 during the larval stage (Appendix 49) and yielded about one and two thirds times as many pounds during its first year in the fishery. All three winters 1948-49 to 1950-51 were poor smelt fishing seasons in that ice break-ups caused losses of gear and fishing time. The 1950 year class, with eight times the larval abundance of 1948, enters the • fishery in the winter of 1951-52 and, combined with the poor fishing conditions in the preceding years, offers exceptionally bright prospects in that season if weather is at all normal. From R. A. McKenzie's report. '

Appendix No. 51

DIFFERING VERTEBRAL COUNTS IN SMELT WHICH SPAWN.EARLY AND LATE The possible use of vertebral counts in separating different groups of smelt came to light in 1949 when it was found that the early spawners had a comparatively low vertebral number, and in orderly progression this increased to a - significantly higher number on the various spawning grounds as spawning progressed. This change in the character of the fish took place under increasing water temperatures, which is contrary to what would be expected if the spawners themselves were hatched in the same order. That this is usually so is indicated by the fact that the early spawners show a greater first year's growth on their scales, and the later spawners progres- sively less. Further confirmation has been obtained of these differences between early and late spawners. The accompanying table shows average vertebral counts of spawning smelt taken in each quarter of the last three spawning seasons. As the average vertebral counts have been found to be the same in the two sexes of the same year class, the sexes have not been separated in the table. In all year classes in all years the average vertebral number increased significantly from beginning to end of the spawning season. In general the change within any year class is greater as the fish 'grow older. The increase-in average vertebral number with advancing season was more regular in the 1947 year class (1949 spawning season) than in either of those since (1948 or 1949). Average vértebral counts in spawning smelt (numbers in samples in brackets)

Divisions of Spawning Season F„irst Second Third Fourth Year Class Quarter Quarter Quarter .91121±12: Average 1949 1947 year class 61.57 (387) 61.71 (506) 6 1. 93 (467) 62.02 (734) 61.81 1946 year class 61.74 (141) 61.82 (84) 62.07 (188) 62.05 (220) 61.92 1945 year class 61.58 (19) 61.56 (18) 62.25 (24) 62.16 (51) 61.98 125o 1948 year class 61.84 (515) 61.81 (360) 62.23 (245) 62.11 (155) 62.00

1947 year class 61.42 (271) ( 61.86 (349) 62.04 (366) 62.16 (180) 61.87 1946 year class 61.76 (33) 62.15 (20) 62.26 (19) 62.27 (11) 62.o4 1951 1949 year class' 61.68 (360 61.78 (292) 61.79 (193) 62.05 (38 4) 61.83 1948 year class 61.78 (175) 61.79 (47) 61.79 (38) 62.23 (131) 61.93 1947 year class 61.60 _(35) 61.71 (14) 61.79 (33) 62.24 (55) 61.91

The 1948 year class entering the spawning stock as 2-year-olds had a higher average count than either the 1947 or 1949 year classes as they entered the spawning stock, showing that there can be distinct differences in vertebral counts between year classes. It is interesting to note that the average air temperature in May when most of the eggs incubate and hatch was from 2° to 21° F. warmer in 1948 than in 1947 or 1949. R. A. McKenzie

Appendix No. 52 •

RATE OF GROWTH OF MIRAMICHI SMELT It has been shown earlier that the smelt spawning season lasts almost two months and that as a result the young hatched first have almost two months' lead in growth over those hatched last. This is seen not only in the scale growth but in the overall growth., for early 2-year-old spawners (themselves mostly spawned early) may be on the average 1.5 cm. longer than the last spawners of this group, and there may be up to 1.0 cm. difference in 3-year-old fish. With this initial difference the average size of a sample of commercial smelt depends on when and where it is taken and on the proportions of the early and late spawning groups in it. During the last ten years the Miramichi annual smelt catch when graded has yielded from 6% to 23% Extra (7 inches +), 66% to 86% No. 1 (5-1 - 7 inches), and 2% to 20% No. 2 ( 4 - 5-1- inches). When the 1949-50 and 1950-51 catch samples were aged and graded it was found that the various grades were composed of fish of the following ages: 194950 2.912=11 Percentage Percentage . Ages 2- 3= 4- Ages Extra 1 48 47 4 Extra 2 46 47 5 No. 1 50 47 3 X No. 1 60 35 5 0 No. 2 96 4 0 0 No. 2 100 X 0 0 The ages graded as follows: 1949-50 1950-51 Percentage PercentaRe ARes Extra No. 1 No. 2 ARes Extra No, 1 No. 2 2- X 37 63 .2- x 78 22 3 9 86 5 10 90 X .: 62 38 0 Z - 42 58 0 5- 90 10 0 5- 94 6 0 - 75 - - A comparison of the fish approaching 2 years of age (2-) during these two commercial seasons shows that the 1948 year class (2- in 1949-50) were almost two thirds No. 2 grade, while the 1949 year class (2- in 1950-51) were over three quarters No. 1 grade. The differences in the average sizes of succeeding year classes as they enter the fishery are thus striking and of commercial significance. They may be explained by differences in conditions for growth (food, temperature, etc.), in length of the growing season (the 1949 year class began hatching ten days before the 1948), or in proportions of the larger early and smaller late spawned fish. About a thousand smelt from the 1950-51 fishery were weighed individually, aged, and found on the average to weigh as follows: 2- smelt weigh 1.1 oz. 3- smelt weigh 1.6 oz. (45% increase over 2- fish) 4- smelt weigh 2.0 oz. (25% increase over 3- fish) Thus the 2- fish, which have as yet never spawned, may increase their weight 45% between their first and second year t in the fishery. Because the increase in size during the year puts the majority of the fish in the higher priced No. 1 and Extra grades, the added year's growth may easily mean double the value of the individual fish to the industry. R. A. McKenzie

Appendix No. 53 THE YIELD OF SPECKLED TROUT TO A-NGLERS FROM A PRINCE EDWARD ISLAND POND For the ninth year a creel census has been conducted at an artificial 23-acre pond on the North Montague River, P. E. I. The object of the study has been not only to obtain factual data upon the yield of trout to anglers from a representative Island pond, but thereby to reveal the extent of annual fluctuations in the fishery and to- assess the effects of the angling pressure upon the stock. The results of the creel census are condensed in the accompanying table and illustrate the high trout- producing capacity not only directly of the pond but also indirectly of the feeder stream which serves as an excellent nursery for young trout. The total yield and yield per unit effort have fluctuated considerably from year to year, but there is no consistent evidence that one season's yield has affected that of the next. There are as yet no indications of over-fishing. It is suggested that the

- 76 - Yield of Trout to Anglers 1943 1944 1945 1946 1947 19+8l9+9 1950 1951 Number caught 3731 3801 3533 3819 3061 2403 3097 3622 3730 Number of rod-hours - 1516 1632 1634 1723 1351 2144 1868.2054 Number per rod-hour 2.5 2.5 2.2 2.3 1.8 1.8 1.4 '1.9 1.8 Av. total length (in.) - 8.2 8.5 8.1 8 0 4 8.0 8.1 8.2 8.1 Av. weight (oz.) - 3.8 4.5 3.6 4.1 3.4 3.6 3 0 7 3.6 Pounds per acre - 40.7 44.0 37.2 34.1 22.4 30.1 36.7 36.2

annual variations in the anglers' catches resulted largely from differences in the seasons rather than from fishing pressure. Facilities for obtaining the census at the Montague Pond are good and it is planned to continue it in 1952. M. W. Smith

Appendix No. 54 TROUT PRODUCTION IN ARTIFICIAL PONDS ON PRINCE EDWARD ISLAND Although Prince Edward Island waters have an unusually high potential for the production of trout, many of the streams are too small to provide a habitat euitable for the retention and growth of trout to a suitable angling size. However, this potential is often realized in ponds which are formed on the streams, by providing areas for better growth and availability to the angler. Investigations are being conducted to determine the

-maximum number of trout of suitable angling size which can be produced in a minimum of time in artificial ponds. The procedure involves the stocking of ponds with varying densities of trout and the subsequent determination of their survival and growth rates. Four experimental ponds have been available during 1951: Kelly's, Simpson's, Andrews' and Stephenson's Ponds, ranging in age from one to 80 years. Kelly's Pond (80 years; 2.6 acres) has been stocked at the rates of Woo and 800 yearling trout per acre during the past five years. The yield of trout flesh has been determined for 12-month periods. No good agreement between density of stocking and yield has yet been observed. This pond has been restocked at the rate of 800 yearling trout per acre. Year Rate of stocking/acre % Survival Yield 1946-47 400 25 22.8 lb./acre 1947-48 800 25 47 0 3 1948-49 400 54 36.5 1949-50 800 30 28.4 1950-51 400 52 20.0 •

- 77 - For Simpson's Pond (5 years; 2.3 acres), Andrewg Pond (3 years; 3 acres), and Stephenson's Pond (2 years; 3 acres), data upon the growth and survival of the trout and on the yields of trout flesh over about 70-day periods in stinker are given in the following table. Yield per acre is determined from the total final weight less the total initial weight.

N• e ■0 cr) r-I c0 HO Cr•c0 • rrl 0 C \ 4> 0 4-1 ON■0 \D rellrN O 0 7-1 e

• ••••■ I H • CD •I I-I e-I 0 N. ON. 0 .1 co .0 o o o o 0 ▪ r-1 C.) I Cr•ri 0‘ 00 fn o3 C\J C\I .-t (N.1

w . 0 'd 7.4 0 • ti.0 I (11 ergr\ H 0 e e 10000 0 00 00 CN.-00 H •c4 e

U1 G) MI C)' 000HCM ■0 \D trN • e o r-I H H H H 0 0 4-I 7-4 • 0000 O 00 00 • ti 0 00000 000 00 • •-•" '-' PI

e 4-) bD (1) ta G) 0 C\I-.1" N-1-1.4" %.0 1.1"N 0 111 cø e o . 0000 O 00 0 F-1H H H (N.1 0 0 HH Q)• o CCS I-4 I rd • CD o0 r-i fete' CY\ C\I H CC) 0 f■-4 ■C) C CO IC\ 0.) ç'JcoQO tc 0 \ H H O 0

U) e .0..01.cN r-1 \D CV (n0• er4 0 co N.\.0 •■1) A • 114

7.4 1 O 0 'd o 0' e-I CY\ 0 a) p 74 Q0 C\I C‘.1 C\1 00 -1-) cn 0\ OmX) re)C0 ci CY 1--1 H r-I rd "-e 0 c -co o H o r-I 0 H rd • Ir■ 1.rN e -"e trNti O al Q) o o-so\ cro■ oNcroN. ON ON • >i r-1 ri r-I 1-1 r-I (I) H r-I r-i pI 7.4 PI 4-1 4-) La _ 78 ' 1. Although the number of trout introduced into Simpson's Pond in 1951 was doubled over previous years (800 yearlings/acre) the growth rate remained as high. This suggests that a density of 800 per acre does not exploit fully the trout-producing capacity of the pond. To check the 1951 findings the pond will be stocked at the same density in 1952. 2. The yield of trout flesh is governed by two factors, namely the productive capacity of the pond and the survival of the trout. In 1951 the survival in Andrews' Pond was good but the growth relatively poor. A low yield obtained. In Stephenson's Pond a low yield resulted from a poor survival rate, although growth was high. This points to the need for closer observation of the ponds in order to determine the reasons for poor survival. The slowest growth rate has been found in Andrews' Pond and is associated with a greater mean depth and a more abrupt slope of the bottom in this than In the other experimental ponds, where more extensive shallows might be expected to provide better feeding areas for trout. 3. A disturbing factor is the entrance of native trout into the ponds from the tributary streams during the experimental periods.. Their exclusion by screens, particularly during spates, presents a physical problem which has not yet been solved, and requires more attention than has heretofore been put upon it. 4. Notwithstanding the variations in the yields obtained, the results demonstrated the high production of trout that is possible in ponds formed on Prince Edward Island streams. R. M. Spence

Appendix No , 55 POPULATION AND MOVEMENTS OF TROUT IN ELLERSLIE BROOK Part of the young trout in Prince Edward Island streams run to salt water where they grow well and make an Important contribution to the trout fishery in the estuaries and back in the streams. Pond formation is a method of using the young trout in the streams to produce a larger size and ready availability to the anglers, but curtailment of the movements of sea-run trout by dams might so adversely affect the angling in stream systems that the benefits derived from pond formation are only illusory. In 1946 an investigation was begun at Ellerslie Brook to study the effects of a pond upon the brook and sea-run populations, the relationship between these stocks, and the usefulness of a fish-ladder to offset the barrier preented by a dam. Ellerslie Brook has an effective length for tzout production of about 4i- miles.

-79- As the trout move into and out of Ellerslie Brook they are captured in a two-way fish trap located near the head of tide.. The captured trout are enumerated, measured and tagged daily throughout the year. In 1950 a similar trap was erected on the stream just above the proposed pond site to give information upon the movements of trout within the stream and later between stream and pond. An annual creel census records the number of trout that are angled not only in the stream but in the estuary as well, and an attempt is made to obtain records of tagged trout taken outside the Ellerslie system. Dominant inward movements of trout have recurred in late June and early July during the last six years and, except for 1948, in April as well. Another period of inward migration is the fall months at which season the most consistent and largest downstream runs have also occurred. Other more erratic movements are encountered, such as in March (out) and May (in and out), 1949. Movements often appear to be initiated by changing water level, but this cannot be considered the only factor involved since, for instance, the upward runs of June and July may occur when the brook level is low and quite static. The temperature of the water in the estuary may then be a potent factor. The following data show the numbers of trout that have moved (in some cases more than once during the period involed) through the trap at tide-head since June, . 1946. The numbers have fluctuated considerably, and for no apparent reasons the spring and summer runs in 1951 were notably light. April-May June-July Fall-Winter Up Down 'In Down Urn Down 1946 -- -- 902 97 1110 2049 1947 629 197 879 81 1100 1038 . 1948 78 88 563 15 491 1706 - 1949 952 1463 876 153 447 1315 1950 920 465 460 39 126 1136 1951 131 186 316 55 1=0. OffleM1 The annual yields of trout to the anglers for the last five seasons are presented below. Considerable variation has been found, but in general the yields have been sur- prisingly large for as small a stream system as Ellerslie Brook. The majority of the trout that - are captured are young, however, about 80 per cent being in their third year of age. Number Av. total No. per caught length (1n,1 rod-hour 1947 1141 6 0 9 1.5 1948 1086 7 0 0 1.5 1949 1942 6.9 1.8 1950 1608 7.0 1.9 1951 1461 7.0 2.1 -so- Progeny from sea-run and brook stocks of trout, differently marked by fin clipping, were introduced into Ellerslie Brook as fingerlings in 1948 and as yearlings in 1949 to obtain information upon the relationship between these stocks with respect to migration to salt water. Reduction in spawhing area available to the sea-run group by pond formation would be serious if this group were recruited only from sea-run parents and not from the populations of young trout in the streams regardless of parentage. As shown in the following table, a greater proportion of the progeny from sea-run parents have gone to sea. These fish grew at a somewhat faster rate than the progeny from brook parents and this differential growth rate have probably had an effect upon migration and survival. However, it Is clear that the progeny from both groups will run to sea. Number running Number angled Number planted to sea before going to sea Finger- Year- Finger- Year- Finger- Year- Stock lins lings lings ling _ lings

Sea run 1682 764 81 219 3 56 Brook 1638 915 - 83 . 8 33 Among the criteria for gauging the effects of pond formation upon the trout population of the Ellerslie Brook system will be the number of trout moving through , the traps, growth rates and yield of trout to anglers. It is planned to create a pond during the summer of 1952, assuming that the variations in these criteria have been sufficiently well bracketed during the last five years for comparative purposes. M. W. Smith

Appendix No. 56 ESTIMATES OF TROUT AND SALMON POPULATIONS IN ELLERSLIE BROOK, P. E. I. Data on the movements of trout and salmon in and out of Ellerslie Brook have been provided by a fish trap located at head of tide since 1947. The fish trap does not, however, provide information on the fish of the year and yearling population in the stream. To obtain these data, studies on the summer population of trout and salmon in Ellerslie Brook were begun in 1948 and continued through the summer of 1951 to determine ultimately the effect of pond formation upon the population of a stream. Attempts were made in 1950 to capture the total population of trout and salmon in three sections of the brook by means of a direct-current electric shocking apparatus. The results indicated that the capture of the total population in sections of the brook gave more accurate estimates of - 8 1- population than the method of marking, release and recaptur( The marking and - recapture method was used to determine - the stream- population until 1951. During the past summer the population was determined using the total capture method. Twenty-three areas, representing 21% of the effective strew length; were studied, an increase of five areas over the previous summer. Because of the unusually high rainfall in July an August, the effective stream length far exceeded the 7450 yàrds'established by survey in 1950. Population estimates for 1951, however, were based on an effective stream length of 71+50yards. These estimates are presented below and con pared with those of previous years. Year Fingerling trout Older trout Salmon fry Salmon rar

1948* 15500 ■••• MO 5350 -- 1949* 10500 9600 5050 3450 1950* 6450 5670 410 2680 1950** 8700 9220 1620 10680 1951** 4362 5536 505 1976 * by seining ** by electrical fishing The above table indicates a downward trend in the population of trout and salmon. At present it is not known what effect the relative high water of 1951 has upon the stream population. Trout were observed far beyond the usua upper limits of the brook this past summer. This may indic a thinning out and/or a greater survival of trout fry. For the past four years the same 450-yard area of the tributary Hayes Brook has ben subjected to study. The method previous to this past summer has been to take sample sections, usually 50 yards in length, and from these sample sections determine the population of the 450-yard area. In 1951 the whole 450-yard area was fished and the population figures presented below, and compared with previous years, represent the total capture of the area. Year Fingerling trout Older trout 1947* 588 • 351 1948* 729 342 1949* 850 380 1950* 426 312 1951** 850 380

* by seining ** by electrical fishing (total capture) -82- The population of older trout in Hayes Brook has been very constant. Population figures for the trout fry vary, by as much as 100%. Trout tagging in other streams Elle rslie fish trap data have revealed that a large number of non-native trout move Into Ellerslie Brook and a tagging program was initiated this past summer to determine the streams from which they come. Four hundred and twenty-five trout were tagged in twelve streams within a radius of thirty miles of Ellerslie Brook. The electrical fishing apparatus was used to capture fish for tagging and an opportunity was thus provided to look for tagged fish from Ellerslie Brook in these streams. They were found in three streams from which no reports of capture have been made to date. Tagging was done in June, at which time the sea-run trout could be differentiated from the native brook trout. It is hoped that this program will provide additional information on the movement and distribution of sea-run trout. J. W. Saunders

Appendix No. 57

FERTILIZATION AND PREDATOR CONTROL AS MEASURES TO IMPROVE TROUT ANGLING IN NATURAL LAKES Creel censuses maintained for a number of years on lakes of Charlotte County, New Brunswick, disclosed poor yields to anglers of native and introduced speckled trout. Limnological studies demonstrated that the low yields of trout were correlated with a poor fertility of the waters. Commer- cial inorganic fertilizers were added to Crecy Lake in 1946 and to Gibson Lake in 1947 to determine if the productive level, especially of trout, in these small natural lakes could be improved in an economical and worthwhile fashion by this manipulation of the chemical environment. In following this procedure it became evident that predatory binds, mammals and fish were important factors in the survival of trout and that at least the birds appeared attracted in Increasing numbers by an annual stocking of trout. In 1949 control of fish-eating birds and mammals was initiated at Crecy Lake, and a year later a program of reducing the numbers of eels, the most serious predatory fish, aside from trout themselves. Coincident with a greater survival of trout to anglers in Crecy Lake in 1950 there was a decline in the improved rate of trout growth that followed the fertilization in 1946. A second comparable fertilization of this lake ceas carried out in 1951 to establish whether both growth and survival could be improved by concurrent - 83 - - application of fertilization and predator control. Anticipating a greater trout-producing capacity, the number of introduced trout was doubled in 1951. Predator control was not exercised at Gibson Lake, which will serve as a control in this respect, but the lake was again fertilized in 1951 and the doubled. stocking

The amounts of fertilizer have been sufficient to give concentrations of 0.39 mg of phosphorus and 0.21 mg. of nitrogen per litre in both applications to Crecy Lake and one half these concentrations in Gibson. Distribution of the fertilizer has been made in June or early July. In both lakes added phosphorus disappeared rapidly from the water so that by fall of the year of application concentrations of both soluble and total phosphorus appro- ximated pre-fertilization levels, and showed no resurgence in following years. Very heavy blooms of blue-green algae developed in the lakes by late summer in the years of fertilizing and gave evidence of a strong, if temporary, entrophication. Such blooms are abnormal for the lakes. An adverse effect of fertilization ras illustrated by the reduction of the dissolved oxygen to a mean value of 3 ml. per litre in Gibson Lake during the late winter following the first application of fertilizer.' However, no fish mortalities could be attributed to this deficiency, which was much more pronounced than found in Gibson before or since or in Crecy Lake. The fertilization of Crecy Lake in 1946, but not of Gibson in 1947, resulted in an improved growth rate of trout to the extent that introduced fingerlings were of sufficient size to enter the anglers' catches the year after planting, a situation not previously encountered in these or neighbouring lakes. The improved growth rate of the fingerlings in Crecy Lake was largely responsible for a definite improvement in, the yield of trout to anglers in 1947. Although the good rate of growth persisted into the second and third seasons after fertilization, the yield to anglers declined. Following the incep- tion of predator control in 1949, survival again improved but growth rates deteriorated. Slower growth of the trout, and other events, suggested dissipation of benefits from the first fertilization'of Crecy Lake and prompted a second treatment in 1951. During the summers of 1950 and 1951 eels have been captured in baited traps set in Crecy Lake. Six such traps continually set from June 12 to August 2, 1951, captured 105 lb.; however, this number represented a small percentage of the eels present in the lake during that period for subse- quently from August 9 to October 9, 460 lb 0 were captured in a trap in the outlet as they attempted to run from the lake. Others undoubtedly remain in the lake. The procedure is rather ineffective in controlling the number of eels, but apparently made some contribution to the greater survival of Table 1. Growth and Survival of Planted Trout Av 0 total length (in.) When % survival When angled to anglers planted a year Inc- a year Stock (yearl later rease later Crecy Lake (50 acres; 7.8 ft 0 mean depth)

Unfertilized yearlings 7 0 5 (1945) 10.1 2.6 10.2

1st year after yearlings 8.4 (1946) 11.4 3. 0 16.7 fertilization fingerlings 3.2 (1946) 8.5 5.3 3.6 2nd year after yearlings 84 (1947) 12.2 3.8 3.9 fertilization fingerlings 2.9 (1947) 9.3 6.4 0.5

3rd year after yearlings 6.4 (1948) 11.9 5.5 1. 8 fertilization fingerlings 2.4 (1948) 8.4 6.o 0 .3

4th year after yearlings 7 0 3 (1949) 10.5 3.2 28.6 fertilization* fingerlings 2.6 (1949) 7 0 5 4 0 9 0.9

5th year after yearlings 7 0 3 (1950 ) 9.8 2.5 45.0 fertilization** fingerlings 3.3 (1950 6.7 3.4 14.8

Gibson Lake (59 acres; 13.2 ft 0 mean depth) Unfertilized yearlings 8.4 (1946) lo.4 2.0 12.0 fingerlings 3.2 (1946) 4.5 1.7 0.2 1st year after yearlings 8.4 (1947) 10.5 2.1 3.8 fertilization fingerlings 2.9 (1947) 5.5 (only two recaps.) 2nd year after yearlings 6.7 (1948) 10.5 3.8 2.1 fertilization fingerlings 2.4 (1948) (no recaptures) 3rd year after yearlings 7.1 (1949) 8.5 1.4 (i7 fertilization fingerlings 2.6 (1949) (no recaptures)

4th year after yearlings 7 0 3 (1950) 9.8 2.5 2.2 fertilization fingerlings 2 0 6 (1950) (no recaptures)

* Bird control initiated in 1949 and ** reduction of eels in 1950. - 85 - Table 2. Yield of Trout to Anglers

Crecy Lake

1943 1944 1945 1946 1947 1948 1949 1950 1951

No. caught 167 148 - 143 425 110 39 264 1441 No. per rod-hour 0.4 0.5 - 0.6 1.0 0.3 0.15 0.6 1.4 Lb. per acre 2.1 1.3 - 1.5 3.6 1.6 0.8 2.7 6.4 Gibson Lake

No. caught - trout 20 5 8 82 50 30 27 27 - salmon 44 47 57 21 17 5 3 0 No. per rod-hour (trout and salmon) 0.3 0.4 0.5 0.3 0.2 0.1 0.1 0.1 Lb. per acre (trout and salmon) 0.7 0.5 0.8 1.1 0.8 0.35 0.3 0.3

trout in 1951. Complete control of eels could be effected by preventing the upward migration of elvers into the lake. An e attempt in this direction was made in 1951 by erecting a dam in the outlet. By passing all of the water over a vertical fall of about two feet, the upward movements of elvers was apparently stopped, but proof that this occurred will necessarily await demonstration of disappearance of older eels from the lake in future years. Summaries of data upon growth and survival of trout and yield to anglers for Crecy and Gibson Lakes are given in Tables 1 and 2. Predator control as practised at Crecy Lake has required the attention of a guardian resident on the lake throughout the year. M. W. Smith

Appendix No. 58 FIELD TESTS OF ELECTRIC FISHING IN NEW BRUNSWICK During the period July 18 to 29, 1951, a number of field tests were made with the two electric fishing outfits then available at the Atlantic Biological Station: (1) Wolf machine, capable of delivering 550 volts, D.C., and (2) Onan generator rated at 110 volts, D.C., but capable of providing up to 160 volts when run at high speed. The tests were made to evaluate more fully the usefulness of these outfits in the capture of various species of fish under diverse habitat conditions in fresh water, and to co-ordinate data upon fish captures with water characteristics, physical nature of the Approx. , fishing Depth of water % recapture of marked pH of Resistance area - (inches) Nature trout and salmon Site water (ohms) Av.V Max. of flow (Two sweeps per area) Campbell • • . " . Brook 6.7 25750 2000 5 lo rapid 35 Digdeguash ' 24400 V .River 6.7 -26350 . Shallow area 440o 8 20 rapid Deep area 900 20 45 pool, weak e to moderate

Presque Isle ' 3603 V River . 8.0 -3860 V . Shallow area . 1800 8 15 rapid 61 - Deep area V 1650 24 42 moderate to rapid 31 Whitemarsh 8.1 3930 1275 6 24 rapid 36 ... -3988

Results with Wolf machine except in Whitemarsh Creek where only Onan machine was employed. - 87 - habitats and mechanical performance of the machines. The personnel of the party that carried out the A' tests was H. Y. Brownrigg, P. F. Elson, H. Godfrey, C. R. Hayes, J. W. Saunders, G. F. M. Smith and M. W. Smith. The tests were made in the soft waters of the Dig- deguash River, Campbell Brook and littoral areas of Gibson Lake, Charlotte County, and In the hard waters of the Presque Isle River and Whitemarsh Creek, Carleton County. Each fishing area, with the exception of that at Gibson Lake, was enclosed by net barriers. Approximately fifty marked individuals of hatchery fingerling and yearling trout and yearling salmon were distributed in each fishing area in the streams, as well as a variable number of marked native fish which were seined at the site of operations. In the soft waters of Digdeguash River and Campbell Brook the Wolf machine delivered under load about 550 volts at 1 amp. and stunned fish, but the Onan machine was ineffective. In the alkaline waters of the Presque Isle River and Whitemarsh Creek both machines were effective. Under load in the Presque Isle water the Wolf machine delivered approximately 350 volts at 3.0 amps. Characteristics of the fishing areas and the percentage recapture of marked trout and salmon are given in the accompanying tabled In rapid water stunned fish were soon swept out of the electric field around the fishing electrode (a grid 11 by 8 inches) and were often difficult to pick up In dip nets or hand seines before they revived. When the area was sufficiently large many fish, when initially stimulated by the electric field but not stunned, moved out of that field to by-pass the operator and so avoided capture. It was evident that the physical conditions of the waters_often played as prominent a role in the capture of the fish as the effectiveness of the electric outfits to stun them. In some situations electric fishing appeared to have no advantage over seining methods, but as so often is the case it proved its usefulness in capturing fish where seining would be difficult or impossible. In general it was demonstrated that electric fishing is a sampling device varying in utility with chemical and physical characters of the waters„ and with the size and motility of the fish. M. W. - Smith - 88 -

Appendix No. 59 INCREASING SALMON PRODUCTION BY BIRD CONTROL In 1951 the third smolt crop which has been afforded protection from mergansers and kingfishers throughout the freshwater period of its life was measured. This brings to a close a three-year evaluation of bird control as a means of increasing the production of smolts. Production without bird control. Between 1942 and 1946 various experiments were undertaken to determine the best smolt production which could be obtained from an 11-mile stretch of the Pollett River. Hatchery-reared underyearling salmon were used for seeding. The seedings varied in numbers and in degree of dispersal at planting from few fish given wide dispersal to fifteen times as many given 1/100 the original dispersal. In some years most of the fingerlings were planted in the main river and in other years in the tributaries. The production from the plantings was learned by seining parr and by trapping and counting the descending smolts. In three of the five years in which smolt crops were involved the counting weir broke down at times of flood. For these years estimates have been reached through consideration of age groupings (1) in preceding parr populations, (2) In succeeding smolt runs, and (3) by comparison of the numbers of parr found in the river in various years. About 85% of the smolts in this stream descend as 2-year-o1ds and most of the rest as 3- year-olds.

Table 1. Smolt production from the Pollett River without bird control Planting Smolt crop Dispersal Principal (sq. yd. places of Estimated Year. Number per fish) Year Counted yield

1942 16,000 8.5 main river 1944 900 1,000 1943 16 9 000 8.5 main river 1945 174 2 , 000 1944 16,000 2.5 tributaries 1946 . 333 2,000 1945 249,00 0 .085 main river 1947 4,282 4,300 1946 48,000 .097 tributaries 1948 360 1,800

Production scarcely exceeded 4,000 smolts regardless of the method of seeding, and averaged about 2,000. The capacity of the tributaries was similar to that of the main river. Bird predations were seen as the probable limiting factor for production from the main river, but such predation was negligible on the tributaries. Production with bird control. Bird control was introduced after the 1947 smolts had descended. Heavy plantings, comparable to that which had previously given

- 89 - - the best production, were used in three successive years. Pro- tection from mergansers and kingfishers was provided over the entire freshwater life of these fish. The average production of young salmon from these three plantings was 17,821 smolts. Table 2. Smolt roduction from the Pollett River with bird control Planting Parr in river Smolt vield Year Number Year Estimate from seining Year Count

1947 273,000 1948 25,000 1949 19,925 1948 235,000 1949 35,000 1950 13,190 1949 243,000 1950 35,000 1951 20,348 It was thus about eight times better than without control;the poorest yield with protection was three times better than the best without. Nature of bird control used. Removal of mergansers and kingfishers from the experimental stretch of the Pollett River was accomplished through year-round patrols established on a semi-weekly basis. Sometimes other field demands interfered with the regularity of patrols, but chiefly during 'periods when the birds were relatively inactive. While all birds encountered were not killed, a high proportion were shot or tràpped and the patrols tended to keep other birds frigh- tened off. Mergansers. In each of the four years following June, 1947, the patrols recorded an average of 170 sight records of full-grown mergansers. These sight records were judged to refer to between 100 and 150 ducks, of which about one-half were shot. It is believed that these activities resulted in a reduction of the potential removal of yearling parr by ducks from between 60,000 and 100,000 to less than 6,000. The maximum demonstrated capacity of the stream, up to 1951, is about 70,000 parr, and the highest estimate of what the ducks could eat exceeds this by half. Previous to control about 40 ducklings per year (four to fivd broods, or one brood per 20 acres of stream area) were reared on this part of the river, except in 1946. The potential predation by broods living on the river from June to October (about 5,000 duck-days) would approximate that by the flying birds, as discussed above. Mergansers do not eliminate all the fish, but move elsewhere when depletion makes fishing more difficult. For the experimental area of the Follett when many broods are present, this appears to leave about 2,000 smolts; when only flying birds are involved about twice this number of smolts remain. The difference, if real, is rrobably attributable to more thorough fishing habits of the bioods. - 90 - Kingfishers. An average of 182 kingfishers was removed in each of the four years. About 85% of these were taken by trapping and represent young birds of the year. In the light of recent investigations by H. C. White, it seems unlikely that kingfishers are an important factor for salmon conservation, at least as compared with mergansers. P. F. Elson

Appendix No. 60 SALMON PLANTING EXPERIMENTS ON THE POLLETT RIVER Our experiments involving plantings of hatchery- reared salmon fingerlings can be summarized as follows: Phase Period Purpose Results 1 1942-1949 To determine planting Production with all practice for best procedures uniformly production. low - attributed to bird predations. 2 1947-1952 To assess effect of Production increased controlling mergan- three to eight times ser and kingfisher over previous level. predat ions. 1948-1953 To assess value of Preliminary indications dispersal at plant- that dispersal makes ing. little difference within limits tested. 1950-1956 To determine optimal First smolt yield in productivity using 1952. hatchery stock. Phases 1 and 2 are practically completed (Appendix 60). Commencing about 1953 a fifth phase (taking about seven years) is proposed with the principal objects of determining (1) the relative productivity from natural spawning, as opposed to planting, and (2) the numbers of spawners necessary for best production. Effect of_gialat_planting. Phase 3 has been inserted -into the general program by using a section of stream several miles above the main experimental area. Three widely different degrees of dispersal at planting, on each of three similar stretches of river, in three successive years have been used. The fish for each plot have been distinguished by different fin-clips, the same mark being used in each plot for the three plantings there. The nine plantings have used 4,000 fingerlings each. The rates of dispersal - 91 - - have been 5, 50 and 500 fish per yard of stream length. The results will be evaluated through the numbers - of smelts from each planting which are counted at the trap some 15 miles down river. Analysis of the data accumulated to date (Table 1) Table 1.. Numbers of 2-year smelts produced in relation to dispersal at planting

1948 1949 1950 planting planting planting Upper 5 per yard 500 per yard 50 per yard section 947 smelts 1 9 410 smolts smelts in 1952 Middle 500 per yard 50 per yard 5 per yard section 628 smelts 1,129 smelts smelts in 1952 Lower 50 per yard 5 per yard 500 per yard section 1,097 smelts 1 9 475 smolts smelts in 1952 indicates that there is no worthwhile difference in survival resulting from.these different degrees of dispersal. The validity of such a conclusion can be assessed when the 1952 production of 2-year smolts'is measured, and again in 1953 with the final accumulation of data for 3-year smelts. Optimal_productivity usim hatchery stock. In 1950 phase 4 was initiated with a planting of 246,000 fingerlings given a dispersal approximating the intermediate value in the experiment on dispersal; it then appeared that such dispersal would give best results. Plans for planting a much smaller or much larger number in 1951, with the same degree of dispersal , . were postponed when (1) a few mature salmon gained access to the area in 1950, and (2) insufficient fingerlings were available for a heavy planting. Present plans call for plantings of about 1,000 9 000 fingerlings in 1952 and 60,000 In 1953.

• Studies involving adults. In 1950 fifteen adult salmon ascended the Denil fish ladder at the dam forming the lower limit of the experimental area. Only one of the fifteen had been marked as a Pollett smolt - a survivor of the 20,000 descending ine1949. When heavy November floods damaged the pound where these fish were being held, ten escaped, at least four into the experimental area above. A few resulting fry were found in 1951. Although there are reported to be many salmon below the dam this year, only one lad ascended the ladder by October 25. The ladder has, however, been shown to function well and minor improvements are planned. It has become obvious that numbers of salmon are removed Illegally from the river below the dam, so that the value of the fish pass for recording returns of marked fish is limited. . P. F. Elson , - 92 - Appendix No. 61 ESTIMATION OF FISH POPULATIONS AND SALMON SMOLT - PRODUCTION IN THE POLLETT The object of recent fish population studies in the Pollett River has been two-fold. A need was felt, emphasized by repeated breakages of counting fences, for having some method other than count of descending smolts whereby production from the bird control experiment could be measured. There was also the mim of obtaining knowledge about stages between planting and smolt descent. METHODS. A. Getting fish. (1) Seinin: for minimum count on selected areas. The first population studies involved selecting several "representative" areas and attempting, by repeated seining, to catch all the fish. Similar sampling was done each year to learn about annual variations. With this and other methods the sample areas were cut off during seining by barrier nets. The method appeared to give a fair'ly good idea of fish • but contained no inherent means of testing reliabi- Present, lity. It became obvious that the efficiency of removal depended on such factors as character of the stream and ex- Perience of the operators. (2) Seining for proportion of marked fish. (a) On selected areas. To circumvent some Of the shortcomings of the first method, assessments were tried which involved catching, marking and liberating a number Of fish within an area; then the area was re-seined several times to discover the proportion of marked fish to unmarked, the unmarked fish being marked and all fish returned to the water after each coverage of the area. In order that the results from this method could be compared with those from the first method similar "representative" sampling areas were selected. (h) DIL.Al2_:_al_CAILPartly by chance. In the absence of a quantitative survey-of the stream for type of bottom, depth of water, rate of current, etc., both .the above methods were open to the criticism that the sections mIght.not.actually be representative. This year an attempt was made to remove much of the possibility of personal bias in selecting test areas. The stream was considered in sections about 30 yards long; a little less than 8% of the total length was eliminated from consideration as being too deep to seine; the balance was stratified into six sections, proceeding upstream, on the basis of relatively uniform character in each section. From these sections ten sample areas were - — 93 — • picked by chance, the number of areas per section being - pro- portional to the relative length of the section. B. Treatment of data. (1) Minimum count seining. The data obtained this way have been totalled for each species in each year and comparisons of annual populations made on the basis of catches. For salmon parr the catch figures have been applied to the entire experimental area-on a basis of stream length, to estimate the total production from knawn plantings. For this purpose it ras assumed that only four-fifths of the parr present were caught, except in 1950 when electrofishing was done immediately following the seining. This relative catch had been indicated by tests on marked fish. The same catch data have also been used to derive an estimate of parr within the sampled areas on a catch-per-unit-effort basis, and this estimate extended to the entire stream. (2) Seining for proportion of marked fish. These data have been used for deriving estimates for each sample area by Schnabel's method. Estimates for total parr in the river have been obtained by applying the combined estimates from all areas to the total length of river. The series of ten samples involving some chance selection were purposely arranged so that each series of five alternate areas could be used for getting an overall éstimate. RESULTS The results of minimum count seining and simple treatment of data are compared with following smolt runs . in Table 1. Table 1. Minimum count seining in the Pollett River

Fish caught in 7 55-Yd 0 areas, Estimate Smolts counted Catos- Coue- Mini- Salmon of total In following Year tomus sius chthys parr parr year 1948 568 2,639 486 396 25,000 19,925 1949 391 e2,645 1,117 550 35,000 13 9 190 1950 629 1,633 935 633 35,000 20,348 1951 326 2.270 1,335 933 55,000 Average of first three years 3*00 17 9 821 Estimates on a catch-per-unit-effort basis have not been completed, but rhere catching was suspected of having been thorough the estimated and actual catch are very similar. Overall parr estimates of about 55,000 are obtained by either treatment of the 1951 data. • The estimate obtained bv repeated selnings for marked fish in selected arD.ils gave 29,000 parr in 1950. -In 1951 the "representative" areas gave an overall estimate of 75,000 parr and the two series of "chance" areas 69,000 and 65,000.

Table 2. Estimates of total parr in 19,000 vd, of the Follett River, 1951 Size of sample Estimate No. of Stream of total Method sections length , parr

Minimum count - assuming four-fifths catch in selected areas 7 392 yd. 55,000 Minimum count - estimate based on - catch-per-unit effort as above 56,000

Ile..._:,m,Lriarkedfish in selected areas 6 225 75,000* in chance areas (odd nos.)5 150 69,000 in chance areas (evennos.) 5 150 65,000

* One station had a pronounced inflow of cold water and was done during hot weather; parr have been found to accumulate near such cool water under these circumstances. If this station is omitted from the calculations the resulting estimate is 66,000. CONCLUSIONS 1. Methods. Collecting for minimum count of fish in an area may give a fairly close approximation to fish populations, but the efficiency of the method is subject to unknowable variations. A closer approximation to real popula- 'tions is probably obtained by using the data to obtain an estimate on a catch-per-unit-effort basis. Repeated seining for marked and unmarked fish, with treatment of the data on a Poisson series scheme, has the advantage of leading to an estimate of fish present for which some measure of confidence can be expressed. This method is less subject to influence by local conditions and experience of the operators than the foregoing. Selection of "representative" sampling areas pre- supposes a fairly good acquaintance with the stream being tested and with the habits of the fish being studied. In the absence of these, some degree of "chance" selection, using a fair number of samples, is probably to be preferred. 2. Elsh_p2pulations. For the experimental section of the Follett River it would appear that most species • of fish have maintained populations of a relatively stable order of size during the past four years. For the first - 95 - - three years the numbers of salmon parr were relatively more constant than other species. The 1951 parr population has been variously estimated between 55,000 and 75,000 fish, with preference towards about 65,000. By comparison with parr populations and smolt runs in the past, a yield of about 1F0,000 smolts might be expected from the experimental part of the Pollett River in 1952.

P. F. Elson -

Appendix No. 62

't MAGNITUDE OF SMOLT RUNS MEASURED BY SAMPLING A method of estimating smolt runs through the use of weirs which are not required to strain the entire stream has been developed. With partial weirs most of the heavy drift is by-passed and this hazard to maintenance of traps circumvented. Two partial weirs are used, one some distance upstream from the other. All fish taken in the upper trap are marked and liberated; those taken in the lower trap are examined for proportion of marked to unmarked. The total number descending past the lower trap is calculated by: Total smolts caupht below X Total marked smolts liberated above Total marked smolts caught below In the Pollett River the lower (estimating) trap is installed only a short distance above the fence straining the entire stream. This was arranged so that the figures derived by estimate could be compared directly with actual counts. During two years of operation, the two partial weirs have received relatively little attention beyond having the daily catches examined and recorded. Periods of malfunction of both traps have resulted from clogging by drift in each year, although there were no serious breakages. Late in the season of 1950 the lower "sampling" trap ceased to take many fish because of unusually low water, although the upper "marking" trap continued to fish well. Such a condition would result in a low estimate‘-for the late-running fish. Because of lack of attention to the traps the test is not a good measure of the best results which may be expected from sample trapping. - Comparisons between the cumulative smolt counts and the corresponding estimates are shown in the accompanying graphs. The deviation of the cumulative daily estimates from the cumulative counts amounted to t 36% of the estimate in 1950 and ± 35% in 1951. A better measure of the value of the final estimates is obtained from the confidence limits for these estimates indicated in the graphs. • - 96 - Because fish marked and liberated at the upper trap do not descend immediately, estimates based only on daily catches have little value as compared with estimates based on cumulative catches.

(x) estimate rn re;25 0 21,255 1-1

20 x ---- count X / (o) -P X H 14,370 0 0 18,842 ra 15 ta 15 (0) count 4-1 4-1 0 0 . •)e-i.s.. u‘ 0 10 01T e ‘- 0 %)rel 10,365 0 › . -- %.)e (x) estimate › • H ' • 45 L 0 ' r ,e H Jr, g ,e1

C.) à I I I 111111 I I I I I I I 25 30 4 9 20 25 30 May June May A. 1950 B. 1951 Estimation of smolt runs, showing comparison of actual counts from complete weir with estimates from battery of two sampling weirs on the Pollett River, N. B.; data for periods of sample trap operation only, not complete runs. (Confidence limits for final estimates derived from Clopper and Pearson graphs by Adams: J. Wildlife Man. 15, 1. 1951),

In summary: Complete trapping (1) will give an actual count of production - if the trap does not suffer breakage; in this case all measure beyond a poorly-evaluated minimum count is lost; (2) will, barring breakage, make maximum numbers of fish available for marking for future study; (3) can be done with good expectation of success on medium rivers and smaller streams if there is not too much debris carried by the water. -97- Sample trappIng (1) will give an estimate of fish passing the lower trap, for which confidence limits can be assigned, whether or not there is minor malfunction of the traps; (2) will make smaller numbers of fish available for marking but is more certain to give a steady supply; (3) can be done in any stream where such weirs can be installed and made to take some fish throughout most of the season. This method could probably also be adapted for use in studying up-stream runs of fish. P. F. Elson

Appendix No. 63 ECOLOGY OF TBE AMERICAN RGANSER The American Merganser (gemgms_rerganser americanus,)' is a common resident of our Maritime rivers and Is fairly well known in many areas as Shelduck or Sheldrake, names which are applicable also to the Red-breasted Merganser. The Atlantic salmon investigations have shown that it is a limiting factor in salmon smolt production; thus it is important that we have a thorough knowledge of its feeding habits and entire life history. We have extended our study of its feeding habits to cover the main freshwater habitats of the Maritimes and are continuing to collect data on other phases of its life history. Distribution Mergansers are most abundant on our streams when the broods are being reared and are most plentiful on thé best salmon-rearing areas. In the Maritimes they are least abundant on the streams of southwestern Nova Scotia and southwestern New Brunswick where the waters tend to be dark in . colour and have a low production of fish. Broods are not reared on streams which become muddy during high-water periods. The broods require good roosting rocks in pools, or shelving beaches where they can roost beside a pool. Such roosting places are necessary for a quick escape into deep water when attacked by an enemy. The broods, especially the younger broods, are seldom found far from such roosting places. We have found no broods on the fertile Morell River of Prince Edward Island where they are lacking, although this stream is used by the older mergansers during the late fall and winter. Local movements The local movements of mergansers are in relation to reproduction9 feeding and moulting and are affected by ice and water conditions. Young mergansers which are reared on the upper parts of our rivers generally drop down to the lower parts in the

■•■■•■ _ - 98 - late summer or fall. The females tend to stay on their breeding streams as long as water conditions are favourable. On our better salmon-rearing streams non-breeding yearling females may be found in flocks ranging up to twenty at any time throughout the summer and fall. Early in March on estuarial waters we have seen flocks of a hundred or more adult male mergansers without a single immature male or a female among them. In late March or April flocks containing both mature and immature birds of both sexes may be found where there is open water on the lower parts of streams. By mid-June when the females have started incu- bating the mature males drop down to the estuaries and sea coast and then soon go out to sea. The immature males linger somewhat longer and then disappear, probably joining the mature males. A few males may visit the open water of the streams at any time during the fall and winter. • Nests and Ducklings In our area this merganser generally nests in hollow trees but it will nest in cavities in the sides of rocky gorges. Incubation generally begins early in May and the broods are out early in June but an occasional brood may be brought out as much as a month later. This year one nested in a stream-side hollow tree on the Northwest Miramichi. The opening of the cavity was twenty feet from the ground and the nest containing eggs was about four feet down in the cavity. There has been some controversy concerning the method by which the ducklings get from the cavity to the ground. We have examined the late embryonic and newly- hatched ducklings and find them well equipped for the feat. The older ducks have almost-straight blunt claws but the newly- hatched ducklings are equipped with strongly recurved sharp claws. The wings are relatively much larger than those of older ducklings and are equipped with long downy feathers. The tail has a large fan of downy feathers. Their feet are . relatively much larger than at any other time. Their bodies are well padded with down, especially the breast which has a tough skin. Undoubtedly with the use of the wings and claws •they can climb vertical surfaces and with fluttering wings, spread tail and spread feet they can descend safely from any nesting site. On the streams the usual broods number eight or ten ducklings but this year we found a female accompanied by twenty-one downy ones. From the different sizes it was evident that this assembly consisted of ducklings from three broods. Two females within tro miles had only three ducklings each. Eagles were present and ve suspect that they were responsible for the breaking up of the broods. - 99 - Moulting Late in June the mature male mergansers go out to sea where they undergo a moult and become flightless. It is reported that during the summer large flocks of males rest on the sandspits and beaches of the outer islands of Miramichi Bay. It is probable that the yearling males have a similar moult at that time. There is no evidence that the immature females have a complete wing moult but mature females, at least those which rear broods, become completely flightless in late August or early September when their broods are well grown and desert, or are deserted by, their broods. During this period they generally - lead a solitary life but sometimes two are fuund together. In this flightless condition the female is one of the shyest of wild creatures and will dive and go into hiding at the first sign of danger. During our summer collecting few of these would have been collected had we not first spotted them at long range with field glasses. Enemies Owls and eagles are probably beneficial on our salmone streams in keeping mergansers in check. Female mergansers on our larger flood-swept streams are generally successful in rearing most of their ducklings, but on the heavily-wooded areas of some streams they are found with only remnants of their broods. On these areas Barred Owls are often seen in the day- time flying from tree to tree along the bank of the stream. This year we saw one make an unsuccessful attack on a merganser sitting on a rock. The merganser escaped by making a quick dive. At twilight a Barred Owl attached a tame merganser which we had on a tether in a stream. The duck was injured badly and the owl was wet but was still clutching the submerged duck when we intervened. It is known that eagles prey upon mergansers. On our streams the presence of Bald Eagles will cause the merganser broods to go into hiding. The eagles tend to keep the ducks from feeding in the longer shallow areas of a stream. Food In order to make a comprehensive food study of any bird it is necessary to have stomach contents of specimens from a variety of habitats. This year with the assistance of technician H. W. Coates we shot mergansers on most of the larger stream systems and in this work we received and appreciated co-operation from fisheries officers in the various districts. This provided an opportunity to investigate the habitats, to compare the intensity of merganser populations on the various streams, and to collect further life-history data. - 100 - From 26 streams, 329 mergansers were collected. These consisted of 18 non-breeding females, 36 breeding females and 275 young. The young ducks were of all sizes from downy ducklings to those which had started to fly. In addition to these are stomachs of ducks taken during the drives on the Northwest Miramichi and Pollett Rivers. Some late fall and winter collections are planned. Recent analyses indicate that during their first few days of feeding the ducklings feed entirely upon insects consisting of small caddis larvae in vegetable cases, mayfly nymphs and adult insects of various kinds. When about a week old they begin to catch small minnows and suckers and by the time they are two weeks old their diet is largely fish, including salmon parr. For the older ducklings and adults our further analyses are as yet mostly confirmations of previous analyses showing that salmon is a major food wherever parr are available. An unusual feeding habit of young ducks was found on the Economy River in Nova Scotia where two broods of nearly full-grown ducks were restricted to about seven miles of stream between the impassable Economy Falls and the muddy water of the estuary. They had evidently depleted this area of other fishes and were feeding almost entirely upon small eels a short distance above tidal water. Rearing Mergansers For the purpose of making a study of the food consumption and other observations, three merganser ducklings taken on the Miramichi River were kept in captivity from July 5, 1950, to June 11, 1951. During this time they were kept in an outside pen in the Petitcodiac River until December 26 and were then transferred to a pen inside a small house over a pool of spring water. - (a) Winter quarters. The pool occupied all the space in the winter house and, being fed by a running spring, had a temperature of 6° F. to 7° F. throughout the winter. The pen, enclosed by inch-mesh wire screen, was 12 , x 41 x 81 and had an 18-inch resting shelf at one end. It had a board bottom with 30-inch side walls of copper fly screen to retain live food fishes. About one foot of water was maintained in the pen which could be drained for cleaning. The remaining space in the house was floored over, providing a 30-inch floor where food could be weighed, etc. Pontoons for storing live fish were floated beneath the floor. This arrangement provided an ice-free pen where observations could be carried on throughout the winter. (b) Food. The ducks were fed chiefly on river fish taken by seining or by fyke net set through the ice. Other food - 101 - consisted of frozen tomcod and some smelt. For green food, watercress and grass were given regularly. Fine gravel was supplied in a deep dish under water. The quality of the food was a factor in the quantity eaten and apparently affected the vigour of the birds, judged from their flying and playing activities. Killifish were almost entirely rejected and Golden Shiners often rejected. Freshly collected suckers and minnows and small eels and lampreys were readily eaten but fish retained in pontoons for long periods were •accepted in smaller quantities. Cut fish of any kind was not eaten in any quantity and stale fish was rejected. Frozen fresh tom.cod and smelt were eaten in largest quantities and the birds showed increased vigour whén feeding on these. The green food was eaten regularly but in negligible quantity. In the 342 days that these ducks were in captivity they ate 665 lb. of fish, or an average of 222 lb 0 per bird. When nearly full grown, from October to May, the average daily consumption per bird was 11.3 oz., but during a 14-day period when they were . fed on tomcod and smelt only the average consumption was 15 oz., which was 3605% of their body weight. About one third of their body weight appears to be the normal e daily consumption for mergansers. - We considered that the ducks were getting good care and good food but they did not make as good growth as ducks of the same age on-the streams.. We believe that parasites were largely responsible for the poorer growth.

(c) Parasites. While doing stomach analyses of mergansers small numbers of round-worms have been found in the gullet and proventriculus but we have never found them in such numbers as were frequently disgorged by the captive birds. At times they would disgorge squirming masses of worms up to 10 cm 0 in length. The presence of these worms was coincident with the periods when the ducks were being fed on fairly large suckers.

Appendix No. 64 - THE EFFECTS OF EELS ON SALMON PRODUCTION A first report on the eel investigation appeared in the 1950 Annual Report of the Atlantic Biological Station. ' The objectives of the investigation were outlined there, and the first summer's work was described. The present report brings to date the results of certain experiments initiate d . during and since the summer of 1950, and briefly summarizes the field work done during the past year. - 102 - The study was undertaken to determine whether the American eel, as a predator and competitor, seriously affected the production of young Atlantic salmon and, if so, to devise means for its control. Since relatively little is known of its biology and behaviour in this country, the investigation has had to be both exploratory and specific as regards the eel- salmon relationship. As mentioned with more detail in the earlier report, the eel is abundant in most New Brunswick streams, and the evidence of its local distribution and its feeding habits has tended to identify a possible detrimental relationship to salmon. The Nigus Brook ezperiment. This experiment to determine the effects of eel control on salmon fry production from planted eggs was begun in the autumn of 1950. It involved the planting of fertilized salmon eggs in artificial redds in two sections of the same stream. One section had all eels removed from it by repeated electrofishing, while in the other section the eels were allowed to remain. Five redds per section, each with 1,000 recently fertilized eggs, were planted in mid-November, 1950, and two per section, each with 800 eyed eggs, in early May, 1951. This spring, a few days prior to the expected time of fry emergence, specially designed fry-traps were placed around each rédd so that as they emerged the fry could be collected and counted. A comparison of the productions of fry in the two sections was to be made to determine whether they differed significantly. At the conclusion of the experiment, when it was certain that the period of emergence was well over, each redd was dug out and examined to determine the condition of unhatched eggs in the gravel. The experiment gave inconclusive results since, with the exception of two redds, all but a few eggs had died in the early stages of development. When the redds were dug up hundreds of these eggs were found in pockets buried in fine sand and silt which presumably had settled around them and smothered them. Even the two best redds gave less than 100 fry each. The numbers of fry taken in each trap, with underlined figures representing the eel-less section, were as follows: 2, 8, 21 9 0 9 22 9 119 2 9 1 9 09 0 9 09 79 29 10 Experiment to determine rate of predation by eels on planted salmon fry. A uniform section of the Coverdale River was divided into five equal lots by means of frames of copper wire screening. Each lot was 90 feet long and about 42 feet wide. Eels were electro-fished from two of these sections and allowed to remain in the other three. The plan and purpose of the experiment was as follows: (a) to plant an equal number of fry In each of the five sections; (b) to electro-fish eels from the first eel section immediately following the first night's feeding, to make a collection of eels from the second eel section.after two nights' feeding, and a third collection from the third eel section after the third night; (c) to determine the number of fry eaten in each section by stomach analyses; (d) to - 103 - - determine the numbers of fry surviving in a section on the day following the collection of eels from that section; and (e) to determine the number of fry surviving in the two eel-less sections at the conclusion of the experiment. By these means it was hoped to estimate a nightly rate of predation by a known number (and a known size) of eels upon a known number of planted salmon fry. The experiment progressed very satisfactorily until the first dawn collection of eels was being made. Then the electrofishing machine broke down, the necessary repairs and replacements being of such a major nature that the experiment had to be abandoned. ' Natural history studies. Studies of the food of eels are being continued through examination of stomach contents of several hundred eels collected during 1950 and 1951. Age studies, based on examination of otoliths, have been commenced. Behaviour and physiology. A study of the behaviour of eels in respect to certain environmental factors is being initiated, on a laboratory scale, at the University of British Columbia this winter. Two shipments, involving several hundred live eels, have been made from New Brunswick. It is expected that the results of these studies will contribute to an understanding of the ecolo- gical niche of eels and possibly be of help in devising any control measures. From reports by H. Godfrey

Appendix No. 65 EFFECTS OF ELECTROFISHING IN THE VICINITY OF SALMON REDDS For studying the effects of eels on production from salmon redds it was desirable to discover the precautions necessary to avpid injury to developing salmon eggs. Accor- dingly, a series of experiments was undertaken which would more or less simulate the conditions to which eggs might be exposed during electrofishing operations. Salmon eggs in several stages of development were obtained from the Dominion Fish Hatchery at Saint John, N. B. These were variously placed in perforated celluloid or glass containers in (a) a stream bed, to simulate eggs in a redd, and (h) in hatchery troughs, to obtain a more direct effect. Electrofishing, using the regular technique employed in the field, was then done at various distances from the eggs. It was found that (1) eggs buried in gravel may be somewhat protected from electric shock; (2) eggs In early cleavage stages suffered total mortality from severe electric shock; (3) eggs in pre-cleavage stages may be killed - 101+ - but are less susceptible, ().) eggs that were about ready to hatch and alevins were killed by severe shocks (550 volts with electrode one foot distant horizontally) but showed little adverse effect vith moderate shock (same voltage with electrode three feet away), (5) relatively low terminal voltages (around 150 volts) had little or •no ill effect, except possibly on early cleavage stages of _eggs. Observations made during the above experiments indicated that alevins did not respond to direct current in such a way as to make measurement of production from redds through electrofishing practical. From reports by H. Godfrey .

Appendix No. 66 SALMON INVESTIGATIONS IN THE MIRAMICHI AREA The program started in 1950 was continued with interesting and useful results. It is aimed at determining for this large river system (1) the annual production of young salmon over a long period, (2) where they go after leaving the river, (3) the proportions of the Miramichi-produced stock taken by the various salmon fisheries (both commercial and sport) around the coast, (4) the improvement in salmon production that may result from removal of predatory birds (chiefly American Mergansers), and (5) answers to other questions that are important to proper regulation of the fishery such as the proportion of males to females in the grilse runs, and the times of the various runs of fish from the sea into the river. Operation of Northwest Miramichi counting fences. The fence on the White Rapids just above the mouth of the Sevogle tributary was re-installed similarly to but earlier than last year. Except for brief periods when washouts prevented full operation, accurate counts of descending smolts and ascending - salmon were made from May 16 on. A good sample of descending smolts (33,407) was marked by fin clipping for estimation of the total Miramichi run by re-sampling in the estuary, and for future information on their fate. Some returns were recorded of grilse marked here as smolts last year. The times and sizes of the salmon runs were similar to those recorded in 1950. For a short time an additional fence for ascending fish was operated nearby on the Sevogle tributary but with present resources it could not be maintained properly and was removed after interesting information on the gaspereau and shad runs had been obtained. (Appendix 67). Operation of Dun arvon River countin fence. The fence with traps for descending smolts and ascending salmon was re-installed near the mouth cf this tributary to the Southwest Miramichi by May 20. A sample of 15,674 smolts ras marked, and the counts of ascending fish showed that the run was slightly

better than last year. (Appendix 68) 0 . 105 - Capture of smolts in estuary. Good progress was made this year in solving the problem of capturing an adequate sample of smolts in the estuary throughout the smolt run from the entire Miramichi River system. Such a sample is needed to estimate the size of the entire smolt production from the proportion of smolts marked at the two up-river traps to the unmarked smolts. The most effective gear yet tried has proved to be modified double-end smelt box-nets set with long leaders along the shore. In all, 1671 smolts were captured, of which 48 were marked, which leads to an estimated production of 1 9 650 9 000 smolts by the whole Miramichi in 1951. Interesting information on the behaviour of smolts in the estuary was obtained also. (Appendix 69). Bird control experiment and associated estimation of fish populations. Last year a bird control experiment was in- corporated in the Miramichi program to determine whether or not removal of fish-eating birds (principally American Mergansers) could be expected to result in increased smolt production such as has been demonstrated on the Pollett River (Appendix 60). The Northwest Miramichi tributary is to receive bird control for several years by means of organized drives carried out through the co-operation of the Department's Conservation and Development Service. The effects on the production of smolts and other fishes are to be assessed by comparison with the production . on the Dungarvon River where no mergansers are being removed. Later bird control will be shifted to the Dungarvon and mergansers will be allowed to return to the Northwest tributary. The population of salmon parr and other fishes are being followed by a carefully designed seining program on representative sections of both tributaries (see accompanying photographs). The bird control operations have been limited in thé past two years to the brood-rearing period for mergansers, and it is hoped that they can be extended to year-round patrols to provide the maximum effect. Preliminary study of the seining data on the Northwest Miramichi has indicated that the smolt yield (most smolts are three years old here) in 1952 should be twice the 1951 production, probably attributable to the partial protection which has been given by the removal of about 100 mergansers in both 1950 and 1951. C. J. Kerswill 7. • , .•e , - 7 7

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6. Lifting the seine 7. Putting fish in 8. Salmon parr from to catch fish driven bucket for transfer- one coverage of a 50- in; bucket carried ence to live-car. yard-long sample area. by one man.

Assessment of salmon parr production on the upper reaches of the Northwest Miramichi River - 1951. (Photos, except no. 2, by G. F. M. Smith.) - 108 - Appendix No. 67 SALMON TRAPPING IN VICINITY OF WHITE RAPIDS, NORTHWEST MIRAMICHI RIVER In 1951 installation of this counting fence was completed on May 16, two weeks earlier than last year when it was put in for the'first time. . The trap alone was in place on May 9 and some smolts were taken the first night, the earlier- than-expected run probably being associated with a noticeably earlier spring here than in 1950. It is to be expected that difficulties will ever be present in attempting to make an absolute count of smolts and ascending salmon on such a large river as the Northwest Miramichi. Efforts are being made to improve the methods of estimating runs of fish during short • periods when it is physically impossible to. maintain a complete fence. The smolt run as trapped lasted from May 10 to June 27 but over three quarters of them were taken from May 16 to May 23. A total of 33,407 smolt were marked by removing the adipose and left pelvic fin (same mark as in 1950). Conserva- tive estimation of the smolt missed before the fence was complete and on several occasions when it had to be left open put the total 1951 smolt run at 45,000 to 60,000. The upward run of adult salmon had already begun before May 16 and the number missed is unknown, but it is not thought to have been large as the peak of the spring-summer run was not reached until about June 21. The salmon run then dropped greatly but reached a peak again in October, giving a season's total of just under that of 1950, though when allow- ances are made for those missed before the fence was installed and those missed when freshets damaged the fence in mid-July, putting it out of commission for eight to nine days, and again in November, the runs for the two years may be about equal, with 1951 perhaps slightly ahead of 1950. -No grilse were taken until May 28, 12 days after the fence was completed, and so it is believed that few if any were missed earlier. The.grilse run reached a peak about June 20 and this lasted for about a month or until the fence went out of commission about mid-July. An estimated 350 were missed then, for when the fence was repaired the grilse summer run was about over. It picked up again a bit in October. As seen in the accompanying table, the peak of the smolt run in both years occurred in May, of the salmon in October, and of the grilse in July. Returns from the 7 9 969 smolt marked on the Northwest in 1950 were not numerous. Until June 21 it was not feasible to examine thoroughly all grilse trapped and only two of the 317 put through the fence were actually seen to be marked. However, from this date until November 3, 34 more marked grilse were found among just over 1 9 900 passed through the

- 109 - fence. No grilse marked in the Northwest Miramichi were found on the Dungarvon and if this indicates that none went anywhere but to the Northwest then only about 1.5% of the marked smolt came back as grilse. Smolt marked Salmon Grilse 1950 1951 1950 1951 1950 1951 May 7124* 32,286* 0* 53* 1* 28* June 840 1,121 229 253 731 994 July 5 0** 55 51** 1,297 1,017** August 0 0 7 .7 69 79 Sept. 0 0 0 82 42 78 Oct. 0 0 528 316 318 139 Nov. 0*** 0*** 10*** 54*** 1*** 3*** * Fence installed completely, May 31, 1950, May 16, 1951. ** Fence not operating July 13 to 21 - wash-out. *** Fence no longer fishing 100%; removal began Nov. 4, 1950, Nov. 3, 1951 (after wash-out). A number of kelts, both salmon and grilse, were still up-river when the fence was completed and from 175 to 200 were counted down through the fence. 'Many were loath to enter the downward smolt trap and remained above the fence until the mid- July freshet washed out sections giving them an open passage to the sea. A number of them were fed with pieces of gaspereau, shad and sucker for some days while they remained above the fence. By mid-July about forty bright grilse and two salmon were put through the fence going downstream. All were heavily infected with fungus and they may have been returning to salt water to clean themselves. Some were tagged but no recaptures were made. This did not occur in 1950. Damaged by a freshet on November 3-4, the fence was removed thereafter. However, just as the water began to rise spent salmon and grilse collected above the fence and about • fifty were put down-stream before sections of the fence were washed out. Many more are known to have gone down later through the gaps. To check the Sevogle run of salmon and grilse a fence was completed one quarter mile above its mouth by June 14. The box itself was not quite in the main channel and because of this and changing water levels the fence did not function as well as desired. Before all faults could be cor- rected the mid-July freshet so damaged it that it was removed completely and not re-installed. During its period of operation 56 salmon and 277 grilse were put through. It was learned incidentally that while the Northwest has a large run of gaspereau the Sevogle has very few. On the other hand, the Sevogle has a large run of shad and the Northwest not nearly as many. .R, A. McKenzie -110- Appendix No. 68 SALMON TRAPPING AT THE MOUTH OF THE DUNGARVON RIVER The salmon counting fence at the mouth of the Dungar- von River was in full operation on May 20, three weeks earlier than in 1950, and this, apart from seasonal variation, may account for the increase in the smolt count from 262 in 1950 to 15,674 this year. The run was counted from May 17 to June 9, with over 85% of the smolt being taken from May 17 to 23. An unknown number were missed, however, because from May 17 to 20 the trap had no wing racks. Only three salmon were taken during May and these a - few days after the fence was completed, so it is assumed that very few, if any, salmon went up this river before the fence was installed. In the table it is seen that from May to October an average of one to three salmon per day were put through the fence in both 1950 and 1951 (Aug. 19 excepted), but in October the run increased in both years to about 800 fish, three quarters of each year's total. When allowance is made for fish not caught when the fence was not operating fully due to washouts, it is concluded that the 1951 season was slightly better than 1950. In neither year were any grilse taken at the fence in May, hence it is concluded that none were missed by installing the fence as late as May 20. The table shows that July, 1950, was the big month for grilse. However, the July, 1951, catch was much lower (about like the October catch) and this great drop is attributed to some extent to the fact that the fence was out of commission for a week in mid-July. August and September were poor months for grilse, but in October the run increased to about ten fish a day on the average during the last two years. Smolt marked Salmon Grilse 1950 1951 1950 1951 1950 1951 May 14,868* 3* 0* June 253* 98 29* 73 167* 167 July 9 0** 89 50** 971 296** August 0 0 60 10 24 5 Sept. 0 0 92 • 37 64 91 Oct. 0 0 743 818**** 340 255**** Nov. 0* ** 0*** 15*** 0*** 2*** 0*** * Fence installed completely June 10, 1950, May 20, 1951. ** Fence not operating July 14-21, 1951 - wash-out. *** Fence no longer fishing 100%; removal began Nov. 4, 1950. **** Trap not holding fish 100%. Owing to the small number of smolt marked at this fence in 1950, ît is not surprising that no marked grilse were found during the 1951 season, though individual examination

- 111 - was not possible until a regular up-trap was installed in the second week of July, by which time some four hundred grilse or half the year's total had been passed above the fence. - R. A. McKenzie

Appendix No. 69 THE CAPTURE OF SALMON SMOLTS IN TEE ESTUARY OF THE MIRAMICHI RIVER One of the major problems arising from attempts to estimate the total production of young salmon in the Miramidhi River system is to obtain, in connection with marking at smolt traps on the Northwest and Dungarvon Rivers, adequate samples of the resultant marked and unmarked smolts in the estuary throughout the smolt run. Since very little is knaan of the behaviour of descending smolts which might aid in their capture in the estuary, the 1951 program for estuarial fishing included trials with many kinds of fishing gear and techniques. Double-end box nets, trawl nets, shore seines, gill nets and fyke nets were used in order (1) to capture as many smolts as possible, (2) to assess the efficiency of the different types of gear for the capture of smolts, and (3) to gain as much information as possible on the behaviour of descending smolts in the estuary. Number of Smolts Captured Week Millbank Canada Trawl begin- box-net box-net net Total ning Unmkd. Mkd. Unmkd. Mkd. Mkd. Unmkd. gha. Apr. 22 2 2 Apr. 29 0 0 May 6 1 (3) o 1 May 13 8 111 (7) 20 139 N.W. D 703 1Z N.W. May 20 2 667 139 D (16) 34 1 May 27 1 310 g u.w. 0.5) 0 311 uow. N.W. 3 228 3 N °L June 3 26 10 200 3 D (5) 2 4 D June 10 19 97 (4) o 116 June 17 10 56 1 N.W. (2) 0 66 I N.W. June 24 7 28 3 NM. (2) 0 35 3 N.W. July 1 1 2 (1) 0 3 July 8 o 0 o Totals 77 10 1471 n' V- (55) 56 1.D 1604 e4 11-17 . Figures in brackets indicate numbers of trawl hauls or sets. N.W. - Marked in Northwest Miramichi River. D - Marked in Dumgarvon River Canada box net started fishing May 8 0

-112- - The catch of nineteen smolts made by the small experi-- mental fvke nets in the tidal portions of the brooks tributary to the Northwest, Southwest and main Miramichi Rivers suggests that some smolts were migrating soon after the ice disappeared during the firàt two weeks in April. Two box nets, one the "Milbank trap" and the other the "Canada Dock trap", were set opposite each other on the north and south sides of the river respectively just below Chatham and took almost 95% of the smolts caught in the estuary. Gaspereau catches averaging 25 barrels per trap haul during May and June demanded much extra time and effort. The marked contrast between the 1517 smolt caught by . the Canada Dock trap, which was located in strong currents and back eddies, and the 87 by the Milbank trap in weak currents and eddies indicates that water currents have a great effect on the movements of smolts through the estuary. This is strongly supported by the following data on the numbers of smolts caught in the Canada Dock trap at successive slack-water periods. May 21 L. W. 10:30 a.m. 41 smolts HO WO 7:30 Pom. 2 " . May 22 Le W. 2:15 a.m. 214 " H. WO 6°30a 2 " L. W. 12:30 p.m. 131 " H. W. 8:15 p.m. 0 " Almost all the smolts were taken during the ebb tide. That they were moving directly and rapidly seaward was demonstrated when smolts were marked and released from the traps on three separate occasions and were not recaptured. A surface otter trawl, 65 feet long, 50 feet wide and 10 feet deep at the mouth was especially designed for the capture of smolts in the estuary. The gear was fished between Newcastle and Portage Island from the M. B. "Gulf Explorer". Techniques of fishing varied from moored or anchored sets to powered sets at different stages of the tide. Both kinds of sets were equally successful, but the former were more economical and allowed for better control of the gear. Forty-eight of the total of 55 sets were made between Newcastle and Chatham. Average time per set was one hour and thirty minutes. The bridge at Newcastle provided an excellent mooring for stationary sets. Here, too, the narrowness of the river and the strong currents provided good fishing conditions. Success- ful sets were made along the waterfront and in conjunction with the trap nets at Chatham. Results of fishing show an average of about one smolt per trawl haul. The maximum number caught in any one haul was nine. That best catches were made at night with the surface trewl is apparent from the fact that although only one third of the sets were made then, they took well over four fifths of the smolts captured. Moored or anchored sets were most successful _ - 113 - in an ebbing tide. Powered sets caught most smolts during the last half of the ebb and the first half of the flood tides. However, none were taken in hauls during slack water. The trawl also caught a maximum of 10 barrels of gaspereau per haul, good quantities of small and large smelts, eels, and an occasional shad, stickleback, small flounder, small herring and tomcod. Hauls were made with a shore seine at suitable loca- tions along the shore of the estuary from Chatham to Portage and Fox Islands during the last two weeks in June. No smolts were taken by the seine which was about 84 feet long and 9 feet deep. Gill-netting operations consisted of three over-night sets of a surface and bottom string of two nets each 20 feet long and of 1—inch mesh size. Sets were made during the last week in June and the first week in July near Portage Island and Loggieville. No smolts were taken. In connection with the estuarial fishing for smolts hydrograDhic observations were made at surface, middle and bottom depths during eight cruises covering five fixed stations from Newcastle to Portage Island over the period from May 8 to July 4 (see also Appendix 83-H) 0 Evaluation of Results 1 0 Attempts to capture smolts in the estuary resulted in a total of 1671 being taken. Forty-eight had been marked up- river. Since about 48 9 000 smolts were marked (15 9 000 on the Dungarvon River and 33 9 000 on the Northwest Miramichi River) the resulting estimate of production for the whole Miramichi system is approximately 1,650,000 smolts. Limits of confidence at the 95% level are 2,260,000 (37% error) and 1,250,000 smolts (24gerror). These data suggest that a reasonably good estimate has been obtained and, consequently, something approaching adequate numbers of marked and unmarked smolts were caught during the estuarial fishing. However, the fact that less than one half as many smolts were marked on the Dungarvon River as on the Northwest Miramichi River, while almost equal numbers were recaptured, indicates that marked and unmarked smolts were not randomly distributed in the estuary, or that sampling was inadequate. In an effort to improve the sampling, and consequently the estimate of annual total smolt production, attempts will be made next year to capture greater numbers of smolts in the estuary. 2. Since trap nets, when set in areas of strong tidal currents and back eddies, are the most efficient method yet found for capturing large quantities of smolts in the estuary, increased numbers will be used next year. - 114 -

3 0 Although trawl-net fishing at the surface is practic- able for smolts„ it Is an inefficient method of catching large numbers. However, the mobility and the ease with which the trawl can be handled suggests that its greatest value is in exploratory fishing for likely trap-net sites and for information on the habits and movements of smolts in the estuary. . 4 0 Shore seines and gill nets have not been given a proper trial and should prove of value if only for exploratory purposes. L. R. Day and R. A. McKenzie

Appendix No. 70 FOOD HABITS OF HARBOUR SEALS Continued analysis of harbour seal stomach contents shows again a preponderance of flounder, squid and herring in the diet. Over 50% of the total volume of food analyzed was flounder. During the summer of 1951 squid were exceptionally abundant in the lower Bay of Fundy area, and this is reflected by a rise in the percentage of this food item over that of last year. Stomach collections are still not considered large enough to be thoroughly representative of the food habits of harbour seals. (See table, page 115). Because almost all harbour seal stomachs contain cod- worms (Appendix 71), one would rather expect to find in the food more of those fish commonly infested with larval cod-worms. It is probable, however, that the amount of winter flounder taken would keep infestation in the seal fairly well up, and no doubt many of the unidentifiable fish items, being chiefly bottom fish, carry the worm also (Appendix 71). H. D. Fisher

Appendix No. 71 INCIDENCE OF COD-WORMS IN SEAL STOMACHS Identifications of nematode worms in seal stomachs, additional to those recorded in the 1950 Annual Report, are recorded in the accompanying table (page 116). These continue to show that the great majority of nematode worms maturing in harbour seals are cod-worms, Porrocaecum_dmlllenl. In almost all cases recorded, those worms listed as larval, which are too small to be identifleil, are probably also of this species. It seems rather unusual that there are not more of other species of nematodes found in harbour seal stomachs. Others have been recorded elsewhere, and yet of all the worms from 321 harbour, gray and harp seal stomachs collected and

Stomach Contents of 47 Harbour Sealsl No. con- Analysis by Locality taining % by Bay of Fundy N.E.Nova Scotia P. E. I. Common Scientific each item' volume No. No.

Winter flounder Pseudopleuronectes americanus 11 25.3 6 25.1 3 16.0 1 50.0 Smooth flounder Ilopset putnami 2 5.0 1 4.8 3. 4.5 Unidentified flatfish 4 21.8 4 26.3

Squid 19 17.8 13 24.0 6 25.0 1 50.0 Herring Clupea harengus 7 16.4 3 8.1 4 33.5 Cod family Gadidae 1 1.0 1 1.6 Unidentified fish 7 6.9 4 4.1 3 15.6

Shrimp 2 o.8 1 1.4 1 0 .9 itosefish Sebastes marinus 1 2.0 1 2.3

Gaspereaux Pomolobus rseudoharengus 1 2.0 1 2.3 Kelp • 1 1.0 1 4.5 No , of stomachs examined 27(25) 3 16(14) 4(2)

1. Stomachs collected between June, 1950, and August, 1951. 2. Includes occurrences of hard parts such as anal spines, "beaks", otoliths. 3. Numbers in brackets are those containing food.

Incidence of Cod-worm, Porrocaecum deciDiens,- and- of - Contracaecum sp. in Harbour, Grayand Harp Seal - Stomachs (Stomachs_taken in 1951 unless otherwise indicated)

Uniden- Uniden- Total Av. no P. Contra- tified_ tif ied Time of No. of no. of per No.worms decipiens caecum larvae worms Area .year stomachs worms stomach examined A % Harbour seal 'Lower May-June 20 1,562 78.1 467 84.o 0.2 15.0 0.8 Bay of July,Atig. , 6 381 63.5 124 100 Fundy Sep.-Oct./50 6 135 22.5 135 76.0 1.0 23.0

N. E. Jan.-Feb.' 7 933 133.3 174 88.0 1200 Nova Aug. . 1 51 16 63.0 37.0 Scotia Sep.-Oct. 4 472 118.0 97 9900 1.0 Nov 0 -Dec. 150 8 522 65.2 180 87.0 13.0 P. E. I. June 97 24.2 81 98. 0 2.0 Totals: 56 4.153 74.2 11274 87.7 1.1 11.0 0.2 Gray seal Bras d°Or Nov.-Dec./50 7 14,746 2,106.6 7 9 081 97.0 3.0 Lakes . Feb. . 1 560 30 97 .0 3 .0 Ecum Secum, N. S. June 1 608 60 80.0 2000 Totals: 9 15,914 1 9 768 0 2 7 171 97.4 0.2 2.4 Harp seal N&E coast Apr.-May/49 2 32 16 32 31.0 69.0 of Nfld. /51 30 21,423 714.1 859 1.0 80.0 19,0 Magdalen Is. Apr.-May/51 6 uncounted ca0200 60 83.4 16.6 Str.Belle Jan./50 50 uncounted ca.500 100.0 Isle /51 50 uncounted Ca. 500 100.0 - 117 - identified to date only three worms of species other than Porrocaecum and Contracaecum have been found. The gray seals which enter the Bras d'Or Lakes of Cape Breton Island during winter months have been shown to be very important vectors of the cod-worm there (see table). The stomachs of some seals of this species taken were so crammed with adult and maturing cod-worms that it seemed there was hardly room for any food. In such phenomenally high infestations many of the worms pass out through the intestine without maturing, as evidenced by examination of the intestinal tract. There was no apparent detrimental effect on the seals by these heavy infestations. ' - In other parts of the coast, as evidenced by last year's and this year's gray seal material, the gray seal appears to have somewhat different food preferences than those of the harbour seal, as it nearly always has a considerable percentage of Contracaecum in the stomach when harbour seals from the same areas and taken at the same time have almost 100% Porrocaeoum in their stomachs. In harp seals, infestation with Porrocaecum is still

shown to be low on the "Front" or east of Newfoundland, espe- e cially this year (see table). The two stomachs showing 31% occurrence of Porrocaecum were taken in 1949, for which time four other stomachs, recorded last year, showed 3)4 Porrocaecum. The low incidence of this worm on the Front is correlated with the low incidence in fish on the east of Newfoundland. Harp seals, moreover, seem to be entirely free of cod-worms during the southern movement into our coastal waters, as shown by the examination of stomachs taken in January at - the upper end of the Strait of Belle Isle. Later on, however, in the Gulf of St. Lawrence the picture is a different one. Six stomachs of adult harp.seals taken at the Magdalen Islands in April and May this year showbd an incidence of 83.4% Porro- caocum decipiens. At this time the harp seals in the Gulf are feeding, preparatory to making the northward swim to the Arctic. Many of the cod-worms found in these stomachs were mature. - Since the harp seal population in the Gulf contains some 300,000 adul;ts, their effect as vectors of the cod-worm in this area might be serious. There is also the evidence of incidence of 71% cod-worms in four last year, in the form of an ■111. harp seal stomachs taken at Port Hood, N. S., in February before the whelping period on the ice. Whether the effect of a tremendous egg deposition, such as must occur from May until in February, in the Gulf over a compara- June, and possibly of tively short time of the year has much effect on incidence worms in fish in this azea compared with the much smaller but continuous egg deposition taking place from the harbour and The harp seal gray seals in the Gulf, is a matter for debate. infestation might account, however, for the high incidence of area in which - harbour and gray worms in fish in the Gulf - an - 118 - seals are not particularly more abundant than in other areas where the incidence in fish is low. Mrs. Jean Stuart assisted in the identification of worms from seal stomachs. H. D. Fisher:

Appendix No. 72 THE BOUNTY KILL OF HARBOUR SEALS Up to 1949 bounty payments for harbour seals were made upon the submission of the snout of each seal to a Federal fisheries officer, who made out the claims and destroyed the snouts. Such a system is open to fraudulent practice on the part of claimants, since with care imitation snouts have been manufactured which, when salted and dried or else when semi- decayed, have passed as harbour seal snouts. More important, on the east coast of Canada there are six species of hair seals (contrasted with one on the west coast), the snouts of which cannot for practical purposes be distinguished; the bounty is meant to apply to the harbour seal alone. For these reasons, bounty regulations were changed in 1949 so as to require the lower jaw instead of the snout and jaws have since been forwarded to St. Andrews for study. The teeth of all species are distinct, and by this system it has been possible to eliminate fraudulent practice and payments for species other than the harbour seal, particularly for the harp seal. There is evidence of payments for some 400 harp seal snouts annually previous to 1949. The combined initial effect of elimination of Imita- tion snouts and snouts of other species, together with the Initial resentment on the part of hunters to the change was, as expected, to reduce the number of payments greatly. The extent of this reduction in payments can be seen at a . glance in the accompanying graphs showing the number of payments by months in 1948, 1949 and 1950. The 1948 number of payments was about halved in 1949, but the 1950 payments show a definite increase, and it is considered that the present rate of kill of harbour seals is fully equal to and probably greater than that occurring in years previous to 1949. ' In July of last year the bounty rate per harbour seal was raised from $5.00 to $10.00 for seals older than one year and left at $5.00 for pups. In this way it was expected that the older seals would be subjected to a heavier kill, thus more effectively reducing that age group of the population which acts as a cod-worm vector and which is the cause of damage and nuisance to fishing operations. Reaction to changes of this type are slow, since the majority of claimants take young seals during the pupping season in May and June and follow a routine hunting procedure each year, not hunting particularly for older seals because of the greater difficulty in securing them. About 85% of harbour seals - 119 -

Harbour seal bounty claims paid in Maritime Provinces

- 1000

900 1948 191+9

E2 1950 over and 800 above those of 1949

700

600

500

400

■ I •ta. 300 !!. r77-1 4 •

" ra-i 200 cH 1-7-1 • 100

'a F? 5 W223 o o o 4.) o o o • •• e cj>> 04.) 0 0 o o • o >a, O ,c) ;-■ r-t ei (10 P4 4.1 0 e ,c) P M P. ri bD P4 4' › 0 O 00 P4 02 000000 O 00pkooeom000 -120 -

killed each year until 1950 were first-year pups which are not serious vectors of cod-worms and which do not greatly bother fishing operations. While another full year's returns are necessary before forming a definite opinion on the effect of the increased bounty rate for older seals, preliminary results do show an increase in the kill. From January to July, 1950, the proportion of older seals to pups was 15%, while in 1951 for this period it was 20%. An increased kill of older seals, while maintaining the pup kill, will more effectively produce the over-all reduction in the harbour seal population which is being sought in attempts to reduce worm infestation in fish. The rate of reduction under the present type of kill still will not be fast, however, but will have more of a "whittling" effect. H. D. Fisher

Appendix No. 73 SEALS AND COD-WORMS IN THE BRAS D'OR LAKES, N. S. The cod-fish of the Bras d'Or Lakes, Nova Scotia, particularly in the area of Baddeck„ have the highest infestation of worms on the east coast. During the winter there is a considerable population of seals in the lake. They appear in the lakes shortly before Christmas, concentrate in narrow leads during freeze-ups, and by May have left the lakes. Because of the enclosed nature of the'lakes -, the - convenience of working there, and the apparent localized nature of the cod populations, it was felt that here would be an ideal place in which to test the effect of reduction in seal numbers on the incidence of 'worms in the fish. The cod of this area and the life cycle of the cod-worm there are being studied (Appendix 40) and from November to February last winter studies were begun on the seals in the lakes to determine the species - present, their numbers, their distribution and their biology, and to assess the feasibility of reducing their numbers significantly, especially during the freeze-up when the seals concentrate on the ice. Movement of seals into the lakes takes place principally through the Big Bras d'Or Channel, and begins during the first part of November. The only other channel is the Little Bras d'Or connecting with St. Andrews Channel; this, however, is very narrow and winding and passes through well populated districts and seals are seldom seen in it. From November until the end of December the movement of seals into the lakes appears to consist chiefly of gray seals. These are mzst commonly seen in the‘area of Kempt Head and around Lower Washabuck and the mouth of Washabuck River, but some are distributed throughout the lake system and are seen in all parts of the Great Bras d'Or - 121 - Lake. By December 12 the proportion of harboUr to gray seals seen was about 1:25. After Christmas, during January, harbour seals became much more commonly seen, the proportion of harbours to grays being about 4:1. Specimens of gray seals examined included pregnant females. Since this species pups early in February, frequently on land, it was hoped that there were pupping sites in the lake. The pup, like that of the harp seal, does not enter rater for two weeks after birth. If pups could be found it would facilitate control measures against the adults as well as the pups. A thorough search of the lakes during February, however, failed to reveal the presence of any pups, and since the gray seal

. population declined after Christmas it appeared that at least the adult females leave the lakes to pup elsewhere. The most successful bounty hunter in the Maritime Provinces, Mr. Carlie Doucett of Beaver Harbour, N. B., was hired to take charge of the hunting experiments in the lakes. It was found that intense hunting of the seals in open water is at best a slow method of reduction. Both species, but particularly the gray seal, scatter very fast and far after the first one or two shots. During the pre-Christmas field work ten seals (nine gray and one harbour) were killed, and after Christmas twelve seals (ten harbour and two gray) were killed.' The bounty rate of $10.00 per adult seal (no pups were observed in the lakes) was advertised throughout the lakes area, and a special bonus of $15.00 per seal of either species was offered to selected persons throughbut the area. This, however, had little effect, only two seals being killed as a result of it. Hunting was done from a heavy skiff equipped with an outboard motor. It was concluded that the use of a larger boat such as the "Pandalus" would allow a more thorough exploration of the lakes system, and operation during weather which limits the use of a skiff. The "Pandalus"„ therefore, will be used for hunting seals this winter and it is hoped that intensified hunting efforts will at least double the number of seals destroyed last year. Such an effort repeated each winter phould gradually reduce the population of seals, though not as quickly as might be desirable for observance of effects on incidence of worms in fish. • For the first time in about 50 years the Bras d'Or Lakes did not freeze over last winter, thus preventing proposed experiments in hunting the seals when they are concentrated in open leads of the ice. This will be carried out in the current winter Ehould the lakes freeze over. H. D. Fisher - 122 - Appendix No. 74 STATUS OF THE GRAY SEAL ON THE EAST.COAST OF CANADA Through direct o>servation„ bounty claims, aerial survey and reports from fishermen and fishery officers, the status of the gray seal on the east coast of Canada is gradually becoming clearer. Whereas two or three years ago the gray seal population south of Anticosti Island was thought to consist of a few breeding individuals on Sable Island and on Machias Seal Island south of Grand Manan„ it is now known that in addition to these areas winter pupping groups occur on Deadman Island in the Gulf of St. Lawrence, in Northumberland Strait on Ice, on Miquelon Island, on shore ice along the north- east Cape Breton coast, and on the Nova Scotia coast in the vicinity of Marie Joseph. There is a seasonal movement of grays In the spring into the Miramichi estuary where several hundred frequent the outer beaches of Neguac and Tabusintac until early winter. There is also a winter movement into the Bras d'Or Lakes. The gray seal on this side of the Atlantic differs from that of the British Isles, but Is similar to that of the Baltic Sea in that it pups early in February instead of in September. On Deadman Island, between one and two hundred pups are taken by Magdalen Islanders each February. No people live there in winter, and last winter the pups were born well up on land inside vacant buildings. In Northumberland Strait many of the gray seal jaws which have been submitted since jaws instead of snouts have been required in support of bounty claims, have come from Amet Island, which in spring and summer apparently is frequented by considerable numbers of grays. In February of this year the Department of Fisheries at Souris, P. E. 10 9 reported that between 1200 and 1500 gray seal pups drifted in and out of Souris Harbour on the ice. During aerial survey of harp seals in March, 1950 9 a herd of about 200 gray seals was seen on mud flats in the Big Barachois, Miquelon Island. These apparently stay in that area throughout the year. Each February gray seal pups are reported on shore ice along the Cape Breton coast from Bay St. Lawrence to North Sydney. These may be offspring from the group which moves into the Bras d'Or Lakes in November. For the first two years after jaws were required in support of bounty cltrins, hunters near Marie Joseph, N. Se, produced jaws of gray seal pups in May and June. Mr. Karl Karlsan of Halifax has reported that on aerial flights over Sable Island in February he has seen numerous white-coat seal pups which at the time he assumed _ - 123 - were harp seals but which have since been determined, through_ correspondence with the Department of Transport supervisor on Sable Island, to be gray seal pups. The population on Sable Island appears to number several hundred. , - The existence of the gray seal in numbers on the north shore•of the Gulf of St. Lawrence and around Anticosti Island has been known for many years. Recently a small herd . has been reported from just below Quebec City on the St.- - and V. D. Vladykov and J. C. Medcof have seen. Lawrence River, small groups on the south shore near Mont Joli. . . It is obvious, therefore, that the species is well . established on this coast. In two areas, the Miramichi estuary and the Bras d'Or Lakes, grays have been taken with large numbers of cod-worms in their stomachs. Since worm incidence in fish in those two areas is very high, a special study is >: being made of the seals there, and possibilities and methods of reducing their numbers is being explored. H, D. Fisher

Appendix No. 75 SEALS IN THE MIRAMICHI ESTUARY In August this year field work was begun in the Miramichi estuary with a view to studying the seal herds in this area and exploring possibilities for reducing the population. Special attention is being given to this area because complaints of damage done by seals to fishing, especially of salmon, are more insistent here than anywhere else on the east coast. Both harbour and gray seals occur- in the Miramichi estuary, end the gray is the more commonly seen and more numerous of the two. Both species concentrate on the north shore of tho estuary between Lower Neguac and Shippegan, possibly because of the suitability of the outer sand beaches In this area for hauling out. Harbour seals are widely scattered and rarely seen in concentrations of more than a few - individuals at one time. Gray seals,on the other hand, congregate at .low tide in hauling-out groups of from six to more than 150 individuals. Being much the larger and more powerful of, the two species, they no doubt appropriate the best hauling-out sites, leaving the harbour seal to scatter to smaller sites. On one instance, however, in August, 1949, a group of about 4o harbour seals was hauled out about 50 yards away from a group of 90 gray seals on the outer beach between Tabusintac and Neguac at a channel known as Seal Gully. The best estimates of numbers which can be made from field work to date is from 300 to 500 gray seals, with harbour seals about one third as abundant. - l2- The fact that the seals are almost continuously harassed by hunters throughout the summer and fall, and yet -are holding their own, testifies to the suitability of the Miramichi area as a seal habitat. Hauling-out sites are located where there is ready access to deep channels leading to the open water of the estuary, and where the seals can see for great distances on all sides. Harbour seals are already widely scattered, and grays will quickly leave an area in which they are being shot at and move to another site. If they are hunted all along the shore they disappear out to sea. While congregation in groups takes place in the area between Lower Neguac and Shippegan, the gray seals range up- river as far as Newcastle, and up smaller tributaries such as the Bartibog and Tabusintac as far as tidal influence. They enter smelt and salmon traps, feed on the fish in them, and either flop out over the top or go out the way they entered. Large seals sometimes simply tear a hole in the net and go out through that. Grays will also raid the salmon drifters' nets out in the mouth of the estuary, and no doubt harbour seals are active in this way too. Suggestions by some fishermen that a type of net trap be designed and tested out on seals were seriously considered and discussed with hunters, fishermen and fisheries officers. It does not seem that such a device would take enough seals to justify the considerable expense involved. At present two methods of control are being considered. One is to have the seals left entirely alone for two or three weeks at a time, and then to make a concerted drive for two or three days. In such a case it is felt that a machine gun mounted in the bow of a fast gas-boat might prove effective. The other is to have the major hauling-out sites mined under the sand, with insulated wire connecting leads leading under water to some spot which can be approached without alarming the seals when hauled out, and to detonate these at an appropriate moment. Such _methods were tried in the Fraser River, B. C., with some success, though there was some difficulty in determining the numbers of seals killed. In the meantime the Department, through this Station, has offered a special bonus of $10.00 per gray seal to selected persons, plus $4.00 for each day that they are engaged in hunting seals, to cover operating costs. Field studies of the seals in the estuary will be continued, and the effects of the special bonus will be observed. H. D. Fisher, from B. A. Mackenzie's notes. Appendix No. 76 POPULATION OF HARP SEALS, AND NEED FOR RESTRICTION OF KILL 1 , Life Historv (a) The following is a briefr6sum6 of the life histOry and movements of the Canadian stocks of harp seals during the course of a year: July-October .- A roving existence in the Arctic, feeding in waters of west Greenland and east Baffin Island. November-January - Southward migration to breeding grounds east of Newfoundland and in Gulf of St. Lawrence. Feeding in both littoral and pelagic waters. February - Northward movement of adults to whelping ice in mid-Gulf and off southern Labrador. March - Females whelp on ice, leave pups about third week, mate with males. Pups moult the white coat and enter water. April-May - Completion of mating. Adults and juveniles haul out on ice to moult, drifting southwest of Newfoundland and west of Nova Scotia. Pups begin northward movement, followed by the first adults and bedlamers to complete the moult. June - Remainder of adults,and juveniles complete the moult and swim north to the Arctic. , (b) There are two breeding - populationrs inVolved in the west Atlantic region - one in the Gulf of St. Lawrence and the other off the east coast of Labrador and Newfoundland (the "Front"). These two populations appear to be distinct on the following evidence: (i)Each year about the same number of seals pup on the ice in mid-Gulf. . (ii)In 1951, despite the fact that there was no general freeze-up in the Gulf and very little suitable whelping ice, the seals pupped there anyway on precarious shore ice off Prince Edward Island. (iii)The Gulf seals on the whole whelp nearly a week earlier than those on the Front. Details of skulls and body proportions are being studied and tagging is being continued in order to discover the - 126 - degree of distinctness between the two stocks. Restrictions on killing are considered with the Front population chiefly in mind, since it is that group which bears the brunt of the fishery. (c) Females generally have been believed to mate at the end of their third year. There Is some evidence to support this view in that: (i) some non-pregnant females examined which had bedlamer markings, no record-.of.previous pregnancy in their ovaries and evidence of maturity.(utéri thickening and mature ovarian follicles) showed"three annual rings in the canine tooth, and (ii)several which had but One functional corpus' luteum in the ovaries and no previous pregnancy scars, showed four annual rings in the canine tooth. (d)Males do not appear to breed actively until about the ' fifth and sixth years. The bacula or penis bones fall into four small-size groups before showing a sudden spurt of growth to a larger fifth and still larger sixth group.

(e) Rates of mortality: The age composition of a sample of about 200 adult seals taken in 1951 from the Strait of Belle Isle and off Newfoundland gives some indication of the - rate of total mortality, i.e 0 kill by industry plus natural mortality -- the latter of which, is probably the major factor. Figure 1, attached, is a graph showing this age composition as determined by reading the annual rings laid down in the tooth dentine by the pulp cavity, and by counting the number of corpora lutea or pregnancy scars in adult female seals for which no tooth samples were available, and adding 3 for the number of pre-breeding-age years. The tooth readings are for both males and females. Figure 2 is a curve for age composition for the adult females only, determined by corpora lutea counts. This shows the same general picture as Figure 1. _ Theoretically, the largest age group should be the 1=year-olds, then 2-year-olds, then 3-year-olds, 4-year-olds, and so on down. The graph does not show this, the 6-year-old class being the largest. If It were true that age classes younger than 6 were smaller in numbers, this would be a bad sign, indicating that a significant reduction in total breeding population is coming up. The smaller size of age groups 4 and 5, however, is thought to be due to biased sampling, the collectors being asked to collect from adults only, and probably regarding many 4- and 5-year-olds as bedlamers as these age groups frequently still have bedlamer-like markings, with no saddle or only an extremely faint one.. If we take age-classes from 6 on, we see that on the whole there is an average annual mortality of 20% or more to about 12 years of age, above which the numbers, though small, do not appear to decline so rapidly. Only two or three individuals have been

Age composition of combined samples of adult harp seals from Strait of Belle Isle (nets) and east coast of , Newfoundland, by tooth rings and corpora lutea counts. 1951.

o = Age if 5 6 7 8 9 39 11 12 lâ 14 15 16 17 18 19 . teN re) ■0 11-% --t Yr. of 0\ 03, 0, 0\ en en (n (r) en el H Ci• O• 0\ 0\ birth 5_i `,j11' g g H ri r-1 H H ri r-I Age composition of sample of adult 99 only from above, by corpora lutea counts. 1951.

c; - • 3 14 15 =Age if 5 à 9 10 1'1 112 1. 16 17 18 - 128 - found older than 19, i.e. with more than 19 tooth rings or with more than 16 corpora lutea in their ovaries. Observations made in the past on proportions of bedlamer age groups by Russians for the White Sea herd (Russian publication by S. W. Dorofejev) suggest that they occur in the proportions of 28% 3-year-o1ds 9 32% 2-year-olds, and 40% 1-year olds, indicating a mortality of 20% from 1 year to 2, and 12e"

from 2 to 3 0 We can safely assume that the natural mortality from birth to one year of age is more.than 20%. 2. Population estimate.s from aerial surve_ An aerial photographic survey of harp seals during . the whelping season in March was repeated this year-in an endea- vour to obtain a check on last year's figures and to - explore . the "Front" more fully. Adverse weather made adequate coverage particularly difficult. The aircraft was grounded during the. - time that ships were entering the whelping patches, so that a considerable kill had taken place by the time it was possible to get good photographs. Also for some unknown reason, possibly because of abnormally loose ice, adult seals were particularly nervous and would leave the ice upon the approach of the air- • craft to a much greater extent than last year. The Gulf herd whelped in two patches this year, one just offshore from Cape Kildare, P. E. 1e, and the other in the western end of Northumberland Strait. A photographic check was made of the former patch on March 4, early in the. whelping season, and of the latter on March 20, when adults had for the most part left the pups. On the Front one large patch whelped a few miles north-east of Belle Isle, drifting because of strong east winds into the Strait of Belle Isle. Another whelped in the Strait just south of this group, and still another between the Groais Islands and the mainland of Newfoundland on the -east coast. A photographic check was made of the first patch on Màrch 8 5 at the beginning of whelping, of the second patch on March 15, and no photography was obtained of the third. The area of the second patch, moreover, was impossible to estimate accurately since it was spread out in irregularly spaced arms. In the Gulf the distribution of seals was very even off Cape Kildare, and photography was done from 300 feet. Estimates made in the same manner as last year resulted in a figure of 115,900 adults and 15 9 840 pups for the Kildare herd on March 4. At this early date the majority of adults may well have been females, but this was not -possible to check and the assumption that 50% were females results in a minimum estimate of about 58,000 for the eventual number of pups produced there. In Northumberland Strait 9 where the adults had for the most part left the pups, the direct estimate of pups from 300- and 600-foot photographic strips was - 160 9 000. This eves a figure for the total pup c:eop in the Gulf cf 218 9 000. This - 129 - agrees rather closely with an estimate of 198,400 in 1950. - On the Front, the distribution again being very even and photography being carried out as described last year, the direct estimate of the herd photographed on March 8 north-east of Belle Isle was 323,400 adults and 101,750 pups. This figure for adults here is considered low because of the nervousness of the animals; whelping was just beginning. The main herd photographed last year was estimated to contain 380,800 adults and 215,700 pups; whelping was complete, the pups numbering 57% of the adults. It is considered that the herd photographed this year was of the same order. In 1950 there was a second patch which could not be photographed but'which both the industrial and our own observer estimated to be as large as the one that was. We are in somewhat the same position this year, the area of.the herd whelping in the south part of the Strait being impossible to determine and the herd on the east of Newfoundland being well hunted before photography could be done. At the present time, therefore, the most logical estimate we can make of numbers Indicates an annual production of pups on the Front of about 430,000, and in the Gulf of half this number, or 215,000.

On the Front the pack Ice along the Labrador coast e was carefully explored this year from shore to ice edge (45 to 55 miles off) northward almost to Cape Chidley, Labrador, without discovering other whelping patches not found by sealing ships. Since sexes are equal at birth, and about equal in catches by nets during the southward migration, we may assume that there are twice as many adults as pups; bedlamers (immatures) equal the adults in the net catches. On this basis there are about 430,000 pups, 860,000 immatures and 860,000 adults on the Front, a total of over two million, and about half these numbers in the Gulf. ' 3. Kill statistics The following table indicates figures for the kill by vessels, both Norwegian and Newfoundland, on the ice since 1946, the firest post-war year in which Norway operated in west Atlantic waters. The year 1951 is treated separately since it was an unusually large kill, close to or perhaps more than what we consider a rational take. Figures refer to catches off Newfoundland.

- 130 - Year Country Pulls Bedlamers Adults Totals 1946 Canada 15,635 11,017 3,426 30,078 ) .36,972 Norway 6,163 731 6,894 1947 Canada 45,618 39,725 16,363 101,706 ) 110 787 Norway 3,899 5,182 9,081 ) 1948 Canada 69,574 34,197 23,573 127,344 ) 151+,821+ Norway 16,376 11,104 27,480 )

1949 Canada 103,280 14,503 12,775 130,558 ) 187,009 Norway 38,774 17,677 56;451 1950 Canada 69,130 8,874 3,323 81,327 Norway 76,949 15,506 92,455 ) 173,782

Totals 445,398 217,976 663,374 67% 33%

1951 Canada 111,000 25,992 25,546 162,080 ) Landsmen 50,000? 50,000?) 0,080 Lady M. 8,000 8,000 ) 34 Norway 80,000? 40,000? 120,000 ) 249,000 91,538 340,080 4. Need for restriction We see then that in 1951 from the estimated annual production of 430,000 pups, 250,000 were taken by sealers, and that 92,000 bedlamers and adults were also taken. This leaves a pup "escapement" of 180,000 which must suffer one year of natural mortality and two years of natural mortality plus killing as bedlamers before in turn producing pups. It must replace the kill of 90,000 adults and bedlamers 21ms the naturàl mortality of these groups (itself about 180,000 on a 10% basis). If we assume then that the escaped pups suffered 25% mortality to one year, 20% to two years, 12i% to 3 years and 10% to 4 years, we would end up with 85,000 entering the 4th year class, which would not be sufficient to maintain the population. The mortality rates, of course, are assumptions, but believed to be conservative, and the need for some restriction in order to maintain the population is clearly indicated, for the present kill seems definitely to be more than the population can stand indefinitely. 5. Protection of adults Consideration of the relative value of pups and adults indicates that the logical place in which to impose restriction is on the killing of older seals. The pup pelt is the one in which industries of both countries are interested, both from the viewpoint of a better quality oil and a more - 131 - valuable pelt. - The fast fur of the white-coat probably - is - worth five - times as much as the skin of an old seal. In addition to being more valuable individually than the adults, more than two pups would have to be saved for each breeding seal which resulted. 6. Method of protecting adults The simplest way in which to restrict the kill on older seals appears to be by the imposing of a closing date early enough to discourage the taking of second trips by the majority of vessels. Second trips are taken generally some time toward the middle or third week in 'April after the bedlamers and 4 . old have congregated in moulting patches on loose ice. The date proposed at Ottawa early in October was April 30. Since quite a few vessels had opportunity this year to hunt in bedlamer concentrations before this date, I feel It should certainly be no later. The effect of such a restriction could be observed and it could be modified another year if necessary. It is not felt that a starting date for killing 1 5 of too much'importance from the conservation point of view, since even though an earlier killing date does allow a greater number

of pup pelts to be stowed, a substantial restriction in the e kill of older seals mould make up for this, for there would be that many more. breeding seals to bear pups the following year. The need for an international agreement is, therefore, an economic one as well as one from the viewpoint of cordial relationships among crews. The Norwegians', it Is unofficially understood, are willing to wait until March 10 before killing, which is several days later than they normally would like. Since it ls only three days earlier than the normal Newfound- land date of March 13, it would not seem too much to expect ou/' industry to agree to March 10 unless they can demonstrate that they are unable to change their "lay" to be of more bene- . fit to the sealing crews by paying them vallies of skins as well as of weight of fat. H. D. Fisher

Appendix No0,77 WEIGHT INCREASE AND FUR FASTNESS IN HARP SEAL PUPS Controversy between Canadian and Norwegian sealing interests over the last few years has centred about the date at which to begin killing the white-coat pups. Norwegian , interests apparently bave a more profitable market for fast- furred white-coats turn for oil or skins of older animais, are anxious to obtain the pups as light in weight as and possible. Canadian interests, on the other hand, are more anxious to obtain the oil from the pups and therefore prefer to take fat, heavy pups although their fur may be slipping and - 132 - not have value as fast fur. To ensure that pups gain considerable weight before being taken, Newfoundland sealers for many years have not begun killing until March 13, Norwegian sealers, wanting as much fast fur as they can get, begin to kill as early in the birth season as possible - right at the moment of birth if they can. During the past two seasons observations have been made on weight increase and fastness of fur 'in pups. Random samples of white-coat "sculps" (skins with fat attached) were weighed each day in which they were available. Fur fastness was tested by pulling firmly on the white fur at various points on the skin. If any fur came away it was considered to be slipping. Furriers in St. John's point out that some furs classified as "fast" in this way may later prove inferior. • . Preliminary results indicate that the white fur remains fast in all pups up to a sculp weight of about 20 pounds, at which time the pup is about five days old. The percentage of fast-furred sculps then decreases steadily with increasing weights until, at 53 pounds or more (2 to 3 weeks old), no fast-furred sculps were found. (See accompanying graph). The season of birth is spread out over more than two weeks, and frequently when a ship has been taking a series of sculps of uniform weight it will suddenly strike a series either heavier or much lighter, indicating that the pups in that group were born earlier or later, respectively, than those previously taken. For the 1951 data in the accompanying graph some of the lighter sculps were taken later than some of the heavier ones, their younger age being obvious from general appearance. The 1950 data, however, are grouped chronologi- cally, the ship from which they were obtained apparently working the same whelping patch throughout. The fur fastness divisions are made principally on the basis of 1951 data, as continuous observations on fur fastness were not made'in 1950. The data suggest that if a date for killing must be agreed upon, those who are interested chiefly in fast fur could wait until sculp weight reaches about 20 pounds and still be assured of obtaining a good proportion of fast-furred pelts. Birth on the "Front" begins about March 6. While March 13 might be a bit late to ensure a supply of fast fur, a reasonable compromise would seem to be about March 10 when sculps from the first pupping groups would be about 5 or 6 days old. The graph also shows some effect of the presence of several ships in a patch of seals on weight increase. For example the "Algerine", from which data were obtained on the northern half of the main patch of seals in 1951, worked alone for the first few days and then was joined by another ship, the crews of both spreading out for some miles in all directions. The more ships and crews in a patch, the more the mother seals are discouraged from getting to their pups - 133 -

• Main patch 1950 D North half, main patch 1951 C)South hall, main patch 1951

52 0

48 - 44 _100% - ,6o% No fast fur' fast fast fur fur 4o -

36 A A

32 A 0 0 0 28 ol 24 (IDEI D 20 - m rti e 16 - oLsti 0 P. • 12 - 1 1 • 4 ) 8 - be g-t 1 1 O 4 F I 1 I 1 1 1 • I Age in days 2 4 6 8 10 12 14 16 18 20

Weight increase and fur fastness in sculps of harp seal pups, east of Newfoundland, 1950 and 1951. and suckling them. The effect of this is to hinder the normal weight increase of the pup. This effect is shown in the reduced rate of increase for the "Algerine" data between five and eight days from birth. The same effect is shown even more clearly by the data on the south half of the main patch in 1951 when the area worked by the "Arctic Sealer", from which the data was taken, was invaded by several ships between the eighth and sixteenth days from birth. The effect is albo evident to a lesser degree in the 1950 data, when the area worked by the "Algerine" was invaded by several Norwegian ships from the tenth to fourteenth days after birth. The data for this report were gathered by Inspectors R. L. Stevenson and T. Reddy, of the Department of Fisheries, St. John's, Newfoundland. • H. D. Fisher

Appendix No. 78 HARP SEAL TAGGING RETURNS There have been three interesting tag returns from the tagging done with Canadian tags by Per Host in the Gulf of St. Lawrence on March 17, 1950, when 125 tagged pups were , released. These three, with the dates recovered, came from: South tip of Greenland, June 17, 1950; Umanak, Greenland, September, 1950; Holsteinborg, Greenland, January 2, 1951. At least two returns from Greenland in the summer of 1950 have occurred from tagging done by Host on the "Front" in March, 1949, using Norwegian tags. All of these returns strongly suggest that a considerable proportion, if not all, of the first-year harp seal pups migrate into west Greenland waters in the summer. Particularly interesting is the return from Hol- steinborg, near the Arctic Circle. This tagged seal was taken at a time when the southward migration had passed the Strait of Belle Isle, and suggests the possibility of some first-year seals remaining in the Arctic for their first winter instead of moving south with the main body. Enquiries are being made to ascertain whether bedlamer or other harps are commonly seen in Greenland during the winter. Further tagging was not done in the Gulf of St. Lawrence this year owing to unsuitable ice on which to land the light aircraft which It had been planned to use. One hundred and sixty tagged white-coats were released from sealing vessels by officers of the Department of Fisheries at St. John's, Newfoundland, and about 30 bearing Norwegian tags were released from a Norwegian vessel. Two of the _ - 135 - seals bearing Canadian tags were taken from the water off Williamsport, Newfoundland, in mid-April. These were tagged in the narrow part of the Strait of Belle Isle in mid-March, and the returns indicate an initial movement of the young pups or "beaters" north-east out of the Strait and south along the east coast of Newfoundland. Tagging will be continued each year in an effort to clarify migration routes. Greenland, Labrador and Canadian Arctic officials have been notified of the tagging and they have passed the information on to natives and other seal hunters. H. D. Fisher

Appendix No. 79 EFFECT OF EEL-GRASS ON OYSTER GROWTH The experiments started in 1948 and 1949 were continued, although the number of oysters remaining from the former was so small as to make it useless to report on their growth here. The oysters were arranged in four groups at random, without reference to their past history, and set out after measurement to grow under the conditions indicated in the accompanying table. The purpose was to test if the presence of eel-grass in close association with the oysters, or the subjection to silting and other bottom conditions were more important in limiting growth. Measurements of weight and of volume (by displacement) were made on a triple-beam balance; length measurements were made with vernier calipers. The results of this year's growth, together with those of the previous years, are gathered in the table. It is difficult to draw general conclusions froM the values presented, since the values for the year 1950 are unlike those for the years 1949 and 1951. The results of this year tend to support the contention of most oyster fishermen that the growth of oysters is poorer in eel-grass; a conclusion which we thought was justifiable in 1949 from the results observed then. A more extensive analysis of the values of the three years may give some.clearer pattern. Observations were made on shape and form of oysters growing in eel-grass on different sorts of bottom. They 1 suggest that the grade of oyster is more dependent on the hardness or softness of bottom than on whether or not it is growing surrounded by eel-grass. Oysters amongst eel-grass plants, but on hard bottom, were of good shape, whereas • those on soft bottom in or free from eel-grass are of the long narrow sub-standard type. A. R. A. Taylor

. Wei ht increase* m. Weight in spring gm. Volume increase Length increase (10 (mm.) Position of oysters 1949 1950 ' 1951 1949 1 50 1951 1949 1950 1951 On bottom: n A-in eel-grass 8.68 in,. 10,68 Ik‘ 6092 ( nn 6.08 6.39 3.26 12.3 10.1 5.7 ) 17:7U " -Li 25.81 ‘‘')/ 43092 "'" (31) (31) B-in clear 1M1 (79) ]_,.2.Ho lî)s (87) (72) (bM 6.13 4085. U..7? 1000 7.1

On stakes e above bottom: :C-in'eel-grass 14 sm? 5.81 5 0 98 16.8 7.0 6.3 (90) e:R. (79) c (77) (31) ... • -

D-in clear 16.41 Inl% 11.42 (nn % )11: ( n6% 10.24 6.43 4.94 17.5 6 0 0 7 0 3 8.76 """ 23.02 ' 1 44-.14 " ' (26) (26)

* All measurements are , mean values. Numbers of individuals given in brackets. Where the number of individuals is not cited, it is the same as that for the weight measurement. - Duration of experiment: 1949 June 3 to Sept. 10; 1950 June 12 to Aug. 23; 1951 May 22 to Sept. 4.

• - 137 - Appendix No. 80 METHODS OF CONTROLLING EEL-GRASS ON OYSTER GROUNDS Covering the eel-grass. All types of covering continue effective. The three plots in Basse Bay at Shippegan, N. B., covered with clamshells, gravel and concrete slabs, set out in 1948, are satisfactory yet, with the oysters continuing to grow well, and with the eel-grass appearing through cracks in the slabs or at the edges of the plots only. The plot covered with chamshells set out at Ellerslie in 1949 and 1950 is in good condition with a few seedlings established in thin places only. The plot in which strips of tarpaper were laid over the eel-grass and covered with sand is continuing effective in its control. In one or two places wave action has moved the sand and threatens to lift the tarpaper. This, and the establishment of new seedlings in the sand e are dangers which may increase in 1952. Cutting the eel-grass. In small metre-square test areas cut and kept clear for one summer season, regeneration over the period of one year has proved sufficient to raise the population again to one quarter or one third of the population of the control areas. Cutting with the Hockney Weed Cutter was carried out again this year on two private leases. This treatment does not result in the general death of plants even after several cuttings of the same area, but it does make the cut area available for easy fishing and might be useful and economical as a co-operative method, particularly if the eel-grass could be harvested and sold. Chemical methods of control. The effectiveness and duration of the treatments made with Benoclor 3 and 3C during the 1950 season were observed this year. The plots to which the Benoclor had been applied as a coating on sand at concentrations of 0.43 qt. per 100 sq. ft. werecompletely élear of eel-grass, whereas concentrations of sprayed Benoclor 3 of twice this, or more, were necessary to achieve the same result. Benoclor 3C was less effective where sprayed, even at these concentrations. Attempts made to dilute the Benoclors with new or used engine oil, in order to make the treatment cheaper, proved that although mixtures which were heavier than water could be prepared, they were less toxic and, in addition, they tended to trap air in the sand and to bring it to the surface. No satisfactory mixture was prepared. Slightly less than three acres of the Department of Fisheries' oyster lease at Shippegan was treated with a mixture of Benoclor 3 and 3C coated on sand at a concentration of one gal. per 1000 sq. ft. This operation was only partly successful as a result of the effect of the tidal currents which are very strong in the area of the lease. They caused a rapid drift of the sand and a loss of the chemical in certain parts of the lease. Effective application seems to have been restricted to periods when the currents were slack or nearly so. These . _ - 138 - difficulties experienced in this large-scale , treatment did show something of its limitations. The Benoclor cannot be spread in the water, even with sand, to give satisfactory treatment with the concentrations suggested if the water moves in such a way as to bring about an uneven distribution of the chemical, or worse, removal of the chemical from the area to be treated. It is suggested that a concentration of somewhat more than the minimum, which we have found to be 0.4 qt. per 100 sq. ft., should be used for safety. A. R. A. Taylor

Appendix No. 81 UNUSUAL MARINE SPECIES ON THE ATLANTIC COAST IN 1951 Several unusual species of fish and invertebrates have been identified at the Atlantic Biological Station or have been reliably reported as occurring on this coast. It seems desirable to place these on record in this report. 1. Prionace glauca L. Great blue shark. Reported as frequent in St. Margaret Bay, N. S., during the summer of 1951 by Mr. L. R. Day. 2. Sphyrna zvgaena L. Hammerhead shark.

Reported from St. Margaret Bay in July, 1951, by Mr. L. R. Day.

3 0 Raja senta Garman. Smooth skate.

A specimen 27 cm 0 long was taken in 50 fathoms, 9 miles north of Digby, N. So, July 28, 1951. Obtained through Dr. J. C. Medcof.

4. Pomolobus sp. Gaspereau or alewife. In 1950 Dr. D. M. Scott provided specimens of this genus from Baddeck River, N. S., which were abnormal in lacking the "saw belly" ventral edge. Mr, W. F. Black made more extensive collections in the same river in 1951 and has found that this condition, due to an abnormal shape of the keel scales, occurs in only about one half of the male fish; the females all have the typical "saw belly". The species is probably P. pseudoharengus Wilson.

5. Argentina silas Ascanius. Herring smelt.

Reported by Dr. W. J. Dyer, Fisheries Experimental Station, Halifax. Taken by the trawler "Venosta" on the banks in early January. - 139 - 6. Notacanthus plusganorus Goode. Reported by Dr. W. J. Dyer from the Grand Banks, Decem- ber, 1950. (Possibly N. nasus). 7. Exocoetus von:tans L. (?) Flying fish. Reported by Dr. W. J. Dyer from a trap'in North-west Cove, St. Margaret Bay, during the summer of 1951. Probably this species. This specimen will be available for definite identification. 8. Benthodesmus atlanticus Goode and Bean. Reported by Dr. W. J. Dyer. Taken by trawler "Venosta" in 90 fathoms, 120 miles ESE from Sambro Lightship in January, 1951 , 9. Pomatomus saltatrix L. Bluefish. A specimen 14 inches long from Minas Basin, mid-July, 1951. Sent to Mr. L. R. Day. 10. Spheroides maculatus Bloch and Schneider. Puffer. Information obtained through Dr. J. C. Medcof from a resident of Kingsport, N. So, where this fish was caught in July, 1951. Although the specimen was not seen, the drawing submitted included so many diagnostic characters that there seems to be little doubt of its identity.

11 0 Mola mola L. Ocean Sunfish. A 500-1b. specimen was reported by the Saint John "Telegraph-Journal", with photograph, from Chance Harbour, N. B., August 16, 1951. Mr. L. R. Day reports several as seen at Ct. Margaret Bay during the summer; six were seen at one - time. 12. Prionotus carolinus L. Common sea robin. A specimen was sent in from south-western Grand Manan In September, 1951. 13. Macrourus berglax Lacépède. Smooth spined grenadier. Reported by Dr . W. J. Dyer as taken by ,a trawler on halibut grounds off the Nova Scotia coast about Mid-April, 1951. 14. Boreogadus saida (Lepechin). Arctic cod. Reported by Mr. R. A. McKenzie from Miramichi Bay in late January and February, 1951. 15. Salpa sp. - A number of salps were taken in Passamaquoddy Bay and at CaMpobello in late August, 1951.

16. Venus mercenaria L. Quahog. A quantity of quahogs was discovered by a fisherman, and confirmed by Dr. J. C. Medcof, in a branch of Birch Cove, Passamaquoddy Bay. This Is believed to be a new record for the New Brunswick side of the Bay of Fundy. 17. Carcinides maenas (L.). Green Crab. In 1930 Miss Rathbun considered the extreme northern limit for this crab to be Thomaston, Maine; but Mr. L. W. Scattergood of the U. S. Fish and Wildlife Service had noted Its gradual spread northward and found one at Lubec, Maine, in 1951. Mr. R. W. Wolfgang found the species to be common at several points in the north-eastern part of Passamaquoddy Bay in the summer of 1951. This is believed to be a new Canadian record. 18. Phvsalia sp. Portuguese Man-of-War. Several specimens were found at L'Etete, N. B., between July 22 and 29, 1951. Confirmed by Dr. D. G. Wilder. Most of the above species are pelagic and the occurrence of some in the Bay of Fundy, e.g. Pomatomus, Spheroides, - Sala and Phvsalia appears to be associated with warm water. The occurrence of Venus and Carcinides is less transient and may indicate a more persistent trend towards warmer water. A. H. Leim

••■ Appendix No. 82

DOES A TICKLER CHAIN INCREASE THE CATCH OF A FLOUNDER DRAG? In considering the operation of an otter trawl such as the small flounder drag, it seems reasonable to believe that changes and,the addition of gear could be used to increase its fishing efficiency. For instance, consider a chain in front of the footrope hung in such a manner that its dragging action over the sea bottom would startle the fish upwards and make them easy prey for the net that folloWs. Such a device has been used in England and called a "tickler chain". In November, 1950, flounder dragging experiments were conducted to ascertain the value of a tickler chain as an aid in increasing the fishing efficiency of the gear. Fundamentally, the tickler consisting of 3/8" chain, is hung between the two lower bridles and assumes the shape of a catenary curve in front of and parallel with the footrope. 11F1 In theory the action of this chain dragging over the sea - bottom about four feet in front of the footrope in the path of sweep would tend to disturb the bottom species and the trawl would follow to sweep them up. The research vessel "J. J. Cowie", skippered by H. H. Butler, made daily trips to suitable flounder areas near Minister's Island and Hardwood Island in Passamaquoddy Bay and carried out twenty- and thirty-minute drags. The net used for these experiments was a standard flounder drag with a thirty- foot sweep footrope and two fathom bridles. These nets are in use in the St. Mary Bay area where flounder dragging is carried out throughout the spring and summer months. The chain was used with alternate drags and all flounders were measured and recorded in groups of small, medium and large, the small less than 25 cm., medium between 25 and 30 cm., and large greater than 30 cm. Standard statistical tests of significance showed that in the small and medium flounders the difference between means mould occur by chance in six and nine cases out of ten respectively. This indicates that in the case of these two group sizes the tickler chain is of no considerable advantage. In the case of the large group (greater than 30 cm.) the in- ' crease in catch would occur by chance in between four and five cases out of ten. The twenty tows used for these calculations, ten without tickler and ten with tickler, caught 237 and 286 flounders respectively. The experiments have not demonstrated an advantage in using a tickler chain. As the gear is on hand, and as even a small difference in catch would justify the low expense of this addition to commercial gear, further experiments are planned not only to determine more reliably what difference a tickler chain produces under the above conditions, but also to test its effectiveness at other seasons. - C. E. Petite

Appendix No , 83 ANNUAL REPORT, ATLANTIC OCEANOGRAPHIC GROUP* Introduction

1. The main function of the Atlantic Oceanographic Group, under the Joint Committee on Oceanography, is the furthering of oceanographic activities in Atlantic waters to meet the requirements of the co-operating organizations represented on the Joint Committee. A further function involves

*Slightly abbreviated and re-arranged by the Director. co-operation and liaison with all organizations interested in the,problem of the waters of the Western North Atlantic. 2. In both of these functions during the past year the Group was eminently successful. A project program, involving seasonal cruises of Canadian Atlantic waters, was carried out, and studies of the submarine-geology of the Magdalen . Shallows were initiated. The trend of rater conditions during' the past year was carefully followed through regular observations at selected stations and considerable accumulated data were analysed and reported upon. 3. Excellent co-operation between the Atlantic Oceanographic Group, the Atlantic*Biological Station, the New- foundland Fisheries Research Station and the Eastern Arctic Investigations resulted in mutual assistance in problems of common Interest.

4 0 Tho Canadian Hydrographie Service, the Naval Research Establishment and the Atlantic Oceanographic Group have continued their co-operative efforts with excellent result2. parsonnel 5. During the past year the staff of the Atlantic Oceanographic Group consisted of the following*: Dr. H. B. Hachey Oceanographer-in-Charge Dr. L. Lauzier Oceanographer Mr. H. J. McLellan Associate Oceanographer Mr. W. B. Bailey Assistant Oceanographer Mr. R. W. Trites Junior Oceanographer (leave of absence from Sept. 26) Mr. E. L. Graham Assistant Technician III (to March 31) Mr. J. A. Sullivan Assistant Technician III (from Aug. 1) Mr. P. O. Hachey Assistant Technician II (March 1 to Sept. 22) Mr. L. H. Brownrigg Assistant Technician I Mr. C. C. Cunningham Assistant Technician I (from March 1) Miss M . M. Meating Stenographer 2A

* The classifications of Fisheries Research Board employees seconded to AOG are listed on page 3 of the staff list of the Atlantic Biological Station earlier in this report. Dr. Lauzier is a member of the Station's staff working with the Group under instruction from the Director. - 143 - 6. Mr. R.W. Trites is presently on leave of absence to do graduate work in oceanography at the Oceanographic Insti- tute of the University of British Columbia. 7. Mr. E. L. Graham resigned as of March 31 to qualify for a commission in the R. C. A. F. 8. Mr. P. O. Hachey, employed for a six months' period, returned to University in September. Summer Employees and Associated Investigators 9. Professor D. G. MacGregor, Head of the Physics Department at Mount Allison University, was employed for the summer season, and with Mr. H. J. McLellan completed an analysis of current data from Grand Manan Channel. 10. Dr. B. H. Ketchum of the Woods Hole Oceanographic Institution spent several weeks at the Atlantic Biological Station during the past summer, and ras associated with the Group in working on the problem of "flushing times" of the Bay of Fundy and Passamaquoddy Bay, the results of which form the subject matter of a paper in preparation for publication. 11. Dr. A. G. Huntsman of the Fisheries Research Board, with assistance from the Group, was involved during the past summer rith investigations of water replacements in Passamaquoddy Bay in relation to herring studies. Dr. Huntsman was also associated with the Group in the preparation of a report and publication on the waters of Belle Isle Strait. 12. Miss J. Towers of the Naval Research Establish- ment spent two months with A.O.G. abstracting data from the oceanographic files for use in a Naval Research project. 13. Messrs. A. Kelland and H. E. Hunt of the New-. foundland Fisheries Research Station spent three weeks with the Group and took part in the late summer cruise of Canadian Atlantic waters. Oceanographic Ships 14. eThe C. N. A. V. "Sackville" has recently been commissioned as an oceanographic vessel and assigned by the Royal Canadian Navy to the Atlantic Oceanographic Group. The "Sackville" began operations in late August, and replaces the C. N. A. V. "Whitethroat" which was recalled in March and re-commissioned as a ship of the Royal Canadian Navy. 15. The "Sackville" is a former corvette which saw considerable service in the Atlantic during World War II. Approximately 205 ft. long, she is driven by an oil-fired steam plant, with a cruising speed of 12 knots and a cruising range of approximately two reeks. She carries a crew of nine officers and twenty-five men. 16. For navigational purposes the ship is equipped with gyro compass, radar, loran, direction finder, and the most modern radio eqUipment. For scientific purposes modern equipment includes an echo sounder which records to depths of 4000 fathoms, a salinity-temperature-depth recorder which electri-- cally records these factors, a GEK recorder for the measurement of ocean currents, and other items such as sea samplers, bathythermographs, deep sea water bottles, and reversing ther- mometers. Several winches, hand, steam and electrical, offer every facility for handling gear over the side of the ship. Amidships, below the main deck, is a spacious laboratory with every facility for work at sea. Quarters are provided for seven scientists in one triple and two double cabins. There are also two smaller deck laboratories.

General Program - 1951 17. A program of oceanographic activities, involving co-operation between the Atlantic Oceanographic Group and the Naval Research Establishment, and the use of three ships, the C. N. A. V. "Whitethroat", the C. N. A. V. "Sackville" / and H. M. C. S. "New Liskeard" included: '(a) four seasonal cruises of the Bay of Fundy, the Scotian Shelf, and the Gulf of St. Lawrence, with one cruise extending over St. Pierre and Grand Banks; (b) a slope water survey as a joint undertaking between N. R. E. and A. 0. G. and involving two ships operating simultaneously; (c) internal wave Investigations; (d) studies of the Miramichi Estuary; and (e) studies, through core sampling of the bottom, -of the submarine geology of the Magdalen Shallows, in association with the Nova Scotia Centre for Geological Sciences. Of this program, due to the lack of ships at the times required, items (b), (c) and (d) were eliminated. Ob- servations made half-hourly over a period of four days on the Scotian Shelf by the Naval Research Establishment, however, provide preliminary data for internal wave studies, and oceanographic observations made in the Miramichi Estuary by staff of the Fisheries Research Board in connection with investigations of salmon, smelt and barnacles form the basis for analysis of some of the factors involved in the problems of a tidal estuary with a comparatively small tidal ampli- tude. 18. A continuing project is concerned with regular observations at representative points along the coast in order to follow the trends in oceanographic conditions. For this purpose observations are made as follows: (a) St. Andrews 2 N. B.: Surface water temperatures taken twice daily, our records extending back to 1921. (b)Lurcher Lightship: Surface and bottom water temperatures taken twice daily, our records involving several years of observation. (c) Halifax Lightship: Surface rater temperatures taken twice daily, and bathythermograph recordings of the water column taken twice daily, our records extending back to 1930 (in : association with the Naval Research Establishment). (d) Halifax Harbour: Surface water temperatures taken twice daily, our records extending back twenty-five years. (e) Entry Island: Surface water temperatures taken twice daily, our records extending back to 1930. (f)Borden, P. E. I.: Surface rater temperatures taken twice daily, our observations initiated this year. • (g) Temperatures and salinities of the rater column, five miles offshore, twice per month. (h)Bay of Fundy: Temperatures and salinity of the water column, once per month, our records extending over a period of twenty-five years. Associated Programs, 1951 19. The Atlantic Oceanographic Group was associated with certain programs of the Fisheries Research Board, the s Canadian Hydrographie Service and the Naval Research Estab- lishment , 20. Oceanographic work related to fisheries involved the Group in certain details of investigations.concerned with herring and salmon projects of the Atlantic Biological Station, and general fieshery projects of the Eastern Arctic Investiga- tions in Hudson Strait and Frobisher Bay. General assistance is, of course, given where required in analysing oceanographic conditions in relation to any project of the Atlantic Stations of the Fisheries Research Board. Closer association is planned with the hydrographie programs of the Newfoundland Fisheries Research Station which In general involves the waters of the Grand Banks and the waters of Labrador. 21. The progrum of the Canadian Hydrographie Service involved the taking of regular oceanographic observations from five ships, one of rhich was to operate in Frobisher Bay where a project of the Eastern 4:.r-:tic Investigations of the Fisheries Research Board was to be prr;secuted. Analysis of 1500 simul- taneous current and wind observations taken at Sambro Lightship between October, 1950, and May, 1950, and an analysis of tidal currents in Halifax Harbour were projects of particular interest undertaken by the Hydrographie Service in 1951. 22. Plans of the Naval Research Establishment involved several hydrographic sections from Halifax outward over the Scotian Shelf to the slope waters beyond. Some General Results 23. From August, 1950, to October, 1951, five offshore seasonal cruises have been completed involving more than 1700 water samples and temperatures, and slides from more than 900 bathythermograph lowerings. These have been supplemented . by more than 2500 bathythermograph records supplied by ships of the R. C. N., the Hydrographie Service and the Fisheries Research Board, and a further 1500 water samples collected by thc Hydrographie Service and the Fisheries Research Board. On the basis of these data a general summary of water conditions on the Scotian Shelf has been prepared covering a period when unusually warm waters have prevailed. A very mild winter in 1950-51, when chilling of the surface waters failed to attain its usual severity, coupled with an incursion of warm bottae waters in the winter months, brought on a period of abnormally high bottom water temperatures and almost eliminated the cold "intermediate" layer which is a typical feature of the waters of the Scotian Shelf. 24. Analysis of surface water temperatures observed during the past ten years in the Bay of Fundy area gives further emphasis to the observations on the Scotian Shelf. As shown in the accompanying figure (see Appendix 83-B), the waters of the Bay of Fundy area have shown a fairly definite trend towards higher temperatures with the highest recorded values in 1951. 25. Current measurements in the Grand Manan Channel made in 1950 with a Geomagnetic Electrokinetograph, and- analysed this year e .have furnished considerable detailed information on the current systems of this area. A southward residual flow was noted for the period of observation, which in some aspects is contrary to previous published information. A detailed survey of the Grand Manan Channel was also made in 1950 which, using methods of rapid sampling, provided data for a very accurate synoptic representation of oceanographic conditions at various ' phases of the tide. 26. Through arrangements made between the Atlantic Oceanographic Group and the Nova Scotia Centre for Geological Sciences, a preliminary investigatioh of the sea floor in the south-western part of the Gulf of St. Lawrence was initiated during the past summer. A special bottom corer was constructed by the Nova Scotia Department of Mines and the Nova Scotia Research Foundation, modified from plans received from the Woods Hole Oceanographic Institution. Cores of the sea floor, - 147 - _ as much as three feet in length, were obtained and the detailed study of these will be under the direction of Dr. D. J. MacNeill of St. Francis Xavier University. 27. The exchanges of fresh and salt water in tidal estuaries have been given considerable attention at various North American centres of oceanography. An empirical theory which describes the changes between various parts of an estuary as a result of tidal oscillations, and which permits the cal- culation of the average distribution of fresh and salt water within the estuary, has been put forward by Dr. B. H. Ketchum of the Woods Hole Oceanographic Institution. Dr. Ketchum spent several weeks at the Atlantic Biological Station during the past - summer, and, making use of data accumulated over a period of years, the "flushing times" of the Bay of Fundy and Passamaquoddy Bay were calculated. The results will form the subject matter of ' a paper in preparation for publication. 28. The oceanographic features of the Strait of Belle Isle form the subject matter of an extensive report issued during the past year under the authorship of Dr. A. G. Huntsman and }fr. W. B. Bailey. The report is presently undergoing revision for publication in the near future. The report treats of the data collected in the Belle Isle Strait Expedition of 1923 and gives ' detailed information on the general water structure involving temperature, salinity and density, the details of the main water masses involved, and the nature of the water movements in the area. 29. The effect of freezing on the sulphate-chlorinity ratio of sea water was studied during the past year. The freezing effects were examined from samples of sea.water frozen in tanks, as well as from samples collected at sea. This investigation, which was commenced at the Scripps Institute of Oceano- graphy by Mr. H. J. McLellan, was continued on the Atlantic coast as offering, in addition to'providing fundamental restilts, a possible index to the origin and thermal history of coastal waters. 30. Water replacements on the Scotian Shelf have bgen followed periodically over a number of years. Within the last two years, the Naval Research Establishment has maintained bathythermograph observations at the Sambro Lightship, so that records are available for following the temperature structure of the water column at this location. During the past year too, the Canadian Hydrographic Service has made over 1500 simul- taneous observations of wind and current. These data, of interest to the phenomenon of water replacements, are being given considerably study by the Group, as well as by personnel of the Naval Research Establishment and the Hydrographie Service. Results to date indicate that the direction, strength and duration of the wind are the main factors which enter into this phenomenon of water replacements. 31. Growth of marine animais is, in part, a function of the water temperature, and on the assumption that cumulated temperatures in degree-months might be correlated with observed growth rates of various marine animals being studied by biologists, data have been analysed, and cumulated temperatures in degree-months have been calculated for both surface and sub- surface waters. It is pointed out that variations from year to year are very large and not very consistent. Data on a monthly basis for representative areas have been supplied to the.fishery biologists interested in correlating these temperature factors with growth rates. 32. The thickness and the salinity of the surface layer in the Magdalen Shallows has been known to reach minimum values during the summer rather than the spring months. It has also been known that considerable variation in minimum salinity . is to be observed from year to year. The amount of fresh water required to produce observed salinities along the north coast of Prince Edward Island has been calculated and these calculated figures can be correlated with the run-off from the rivers of the St. Lawrence. 33. Preliminary studies of the hydrographie conditions in the Miramichi estuary and in the northern sector of Northumberland Strait have been made to provide information relative to salmon and lobster studies. Oceathie Session of'M2_. .SOEciety. 34. Under the auspices of the Committee on Oceanography of the Royal Society of Canada, an Oceanographic Session was held during the Annual Meeting of the Society in Montreal in June. The following papers from the staff of the Atlantic Oceanographic Group were presented: (a) "Some Features of the Surface Layer of the Gulf of St. Lawrence" by L. Lauzler, R. W. Trites and H. B. Hachey; (b) "Hydrographie Features of the Waters of the Strait of Belle Isle" by A. G. Huntsman, W. B. Bailey and H. B. Hachey; (c) "The Effect of Freezing on the Sulphate-Chlorinity Ratio of Sea Water" by H. J. McLellan; (d) "Short Term Fluctuations in the Vertical Water Structure of the Gulf of St. Lawrence" by H. J. McLellan. (e) "Effect of Storms on the Water Conditions in the Magdalen Shallows" by L. Lauzier. aulnalatti_g%ininstitatt _ 35. On invitation from the Engineering Institute of Canada, the writer attended the Annual Meeting of the Engineer- ing Institute of Canada and tock part in the discussion of a paper entitled "The Saint Lawrence Waterway - An All Canadian and Very Deep Route". The paper, as well as the discussion, - 149 - has been published in recent issues of the Engineering Journal. The Associate Committee on Geodesy and Geophysics 36. The regular meetings of the Associate Committee on Geodesy and Geophysics of the National Research Council, two in number, were attended by the writer. Reports of oceanographic activities in Canada are submitted regularly for publication in the Geophysical Bulletin. A report on Oceanography in Canada 1948-1951, as submitted by the writer, was presented to the International Union of Geodesy and Geophysics which met in Brussels in August.' Dr , W. F. Ford of the Naval Research Estab- lishment was the official Canadian delegate representing oceanography. Lectures at the University of New Brunswick 37. As an honorary lecturer at the University of New Brunswick, the writer delivered a series of three lectures during the year. General Liaison 38. Copies of all bathythermograph records were supplied to the Woods Hole Oceanographic Institution and the U. S. Hydrographic Office. In return, records obtained in waters of Canadian interest by these institutions were supplied for our files.

39. Water temperatures from St. Andrews, N. B09 and Entry Island, P. Q., were supplied daily to the.Meteorological Service of Canada. 40. A geoloe class of the U. N. B. Summer School spent a day at the Atlantic Biological Station and were given an opportunity of studying the oceanographic methods in use on the Atlantic coast. 41. A representative of the Canadian Refractories of Montreal, P. Q07 interested in industrial developments using sea water was furnished with required information.

Publications e • 42. Papers from the Group are included in the general list of publications earlier in the Station's report. ManUscript Reports 43. The fcllowing MSS Reports have been distributed during the past year: "Some Features of the Surface Layer of the Gulf of St. Lawrence." Lauzier, L., R. W. Trites and H. B. Hachey. MSS Rept. Joint Committee on Oceanography, March 21, 1951. -150 - "Current Measurements In the Grand Manan Channel." MacGregor e D. G., and H. J. McLellan , MSS Rept. Joint Committee on Oceano- graphy, October 10 1951. "The Waters of the Scotian Shelf, June 1950 to May 1951." McLellan, H. J., and R. W. Trites. MSS Rept. Joint Committee on Oceanography, December 20, 1951. • "The Effect of Freezing on the Sulphate-Chlorinity Ratio of Sea Water." McLellan, H. J. MES Rept. Joint Committee on Oceano- graphy, December 20 1 1951. "A Survey of Water Conditions in Grand Manan Channel in Septem- ber, 1950." McLellan, H. J. MES Rept.- Joint Committee on Oceanography, October 10, 1951. "Short Term Fluctuations in the Vertical Water Structure in the Gulf of St. Lawrence." McLellan, H. J. MES Rept. Joint Com- mittee on Oceanography, December 27, 1950. "Water Replacements on the Scotian Shelf." Trites, R. W. MES Rept. Joint Committee on Oceanography, April 5, 1951. "Hydrographie Features of the Strait of Belle Isle." Bailey, W. B., H. B. Hachey and A. G. Huntsman , MES Rept. Joint Committee on Oceanography April 16 1 1951. -151- Appendix No. 83-A

SUMMER MINIMUM SALINITIES IN THE MAGDALEN SHALLOWS The waters of the western sector of the Gulf of St. Lawrence are known to be highly stratified during the spring and summer seasons. The thickness and the salinity of, the surface layer reach a minimum during the summer. The thinning surface layer during the period of vernal and summer warming indicates inefficient vertical mixing. On the other hand, the decreasing salinities with the advent of summer would indicate efficient horizontal mixing. •The observed minimum salinity along the north coast of Prince Edward Island varied from 25.2%, in 1947 to 27.7%, in 1949. From the variations of salinity and thickness of the surface layer, it is possible to calculate the amount of fresh water necessary to bring about a minimum of salinity. The western Gulf of St. Lawrence has an area of approximately 26,000 square miles, and the drainage basin of the St. Lawrence system is nearly 360,000 square miles. Run-off figures can be converted to a layer of water covering a given area during a given period. Similarly, too, the layer of fresh water required to produce, by mixing, a layer of certain salinity and thickness can also be calculated. Accumulated Thickness of Fresh Water (metres) From variations of salinity and Year From run-off thickness of surface layer 1945 1.48 1.12 1946 0.9 0.83 1947 2.02 1.68 1948 1.32 0 0 97 . 1949 1.42 . 1.02 The resultant calculations, on the basis'of the average run-off for the months of April, May and June, and the thickness and salinity of the surface layer for the months of June, July and August, are shown in the accompanying table. e A good correlation is indicated which suggests the excellent possibility of forecasting the salinity variations of the surface layer during the summer on the basis of the run-off from the St. Lawrence Basin, and also, to a lesser degree of accuracy, the summer minimum salinity along the north coast of Prince Edward Island. L. Lauzier Appendix No. 83-B RECENT WATER TEMPERATURES IN THE BAY OF FUNDY AREA Continued daily observations of surface water temperatures since 1921 at St. Andrews, N. B., had revealed unusually warm or cold years at different times. During the 1940-50 decade the waters of the Bay of Fundy area have shown a fairly definite trend towards higher temperatures with a maximum in 1949 and an appreciable decrease in 1950. The plotted data for the period 1949-50 in twelve- month running averages in degree-months are shown in an accompanying figure. Since 1950, even warmer temperatures have been experienced. From December, 1950 9 to August, 1951, the monthly averages, with the exception of one month, are the highest average temperatures ever observed during the respective months for the period 1921-1950. They rere at least 1.5° C. and as • much as 2.4° C. higher than the monthly normals. From 1921 to 1940 the variations of the running average ranged between 59.0 and 91.8 degree-months, and since 1941 maxima of 93.5, 100.9 and 10304 were reached in 1947, 1949 and 1951 respectively. The minimum recorded in 1950 was as high as the maximum of the 1921-1940 period. For a twelve-month period, the average temperature had reached by September, 1951 9 the highest ever reported for the area. This twelve-month average is still increasing but it is expected to drop by December, 1951. Moreover, the 1951 average from January to December will be the highest ever recorded. The accompanying figure shows a certain regularity in the occurrence of maxima and minima which does not mask the general trend. The periodicity of those extremes seemed to be shorter than during the previous decades of 1921-1940. . It is known from previous work that the Bay of Fundy temperatures reflect general water conditions over a large section of the Atlantic coast; hence the high temperatures in the Bay of Fundy area during 1951 are an indication of a general warming of our coastal raters. From the Bay of Fundy to the central southern Gulf of St. Lawrence the surface water ' temperatures were between 1.7° C. and 2.2° C. higher than the normal; however, this warming was more pronounced during the first five months of 1951 than later in the year. L. Lauzier cn 90 w z 0< cc 2 — 80 w 1— w2 CC Ld 0 70

0 1 I 1 1 1940 19 41 19 42 19 43 1944 1945 19 46 1947 1948 1949 1950 1951

rTe:eMel Twelve months running average of surface water temperatures at St. Andrews, N. B. from 1940 to 1951. - 154 7 Appendix No. 83-C

THE EFFECT OF FREEZING ON THE SULPHATE-CHLORINITY RATIO OF SEA WATER An investigation into the effects of freezing upon the sulphate-chlorinity ratio of sea water which was commenced at the Scripps Institute of Oceanography in April, 1950, was continued throughout the winter months. A large tank with insulated sides and bottom was constructed and filled with sea water on which an ice cover was allowed to develop under natural cooling. Analyses of samples taken from the tank before and after freezing, and from the ice cover, confirm the idea that there is a selective retention of sulphate ions in sea ice and a cons'equent decrease In the sulphate-chlorinity ratio of the waters below the ice. Variations in chlorinity as determined from density and by titration were also studied, but, where they showed any consistency, they were of opposite sign to what would be expected from the abnormalities in sulphate-chlorinity ratios. Further experimental freezings are contemplated. Water samples from the Scotian Shelf, the Gulf of St. Lawrence and the water around Newfoundland have been examined for sulphate-chlorinity ratio and found to vary in this parameter from 0.1380 to 0.1397. Collection of samples continues and it appears promising that the sulphate-chlorinity ratio may serve as index to the origin and thermal history of coastal waters. H. J. McLellan

Appendix No. 83-D THE WATERS ON THE SCOTIAN SHELF - JUNE, 1950, TO MAY,-1951 A report has been prepared on hydrographie data col-. lected on the Scotian Shelf between June, 1950, and May, 1951. Temperature and salinity observations were made.during four - seasonal cruises of the Atlantic Oceanographic Group. Each , cruise occupied twenty-eight stations in four lines running from inshore to well beyond the outer edge of the Shelf. -- These 'lines of stations were supplemented by bathythermograph observations between stations and two lines of bathythermographic observations across the eastern banks. Eleven crossings from four cruises of H. M. C. S. "New Liskeard" during the same period were also considered. The observations permit the development of an unusually warm regime in these waters to be follcred. A very mild winter, when chilling of surface waters failed to attain its usual severity, coupled with an incursion of warm bottom waters in the winter monthI ? brought cn a period of abnormally - 155 - - high bottom temperatures and almost eliminated the cold "intermediate" layer uhich is a typical feature of the Scotian Shelf. In August e 1950, two temperature sections were obtained over the central section of the Shelf separated by an interval of seven days. Two days before the second crossing a severe tropical storm passed along the Nova Scotia coast and' completely upset the temperature distribution in the waters. Piling up of surface waters reduced the strong thermocline, where gradients as high as 2° C. per metre had been observed, to one uhere the maximum gradient was 0.3° C. per metre. The intermediate layer, except for a small volume close to shore, was driven from the area, and a body of water with temperatures as high as 10° C. invaded the deep basin inside Emerald Bank. The data for this period suggest that the cold water layer on the Scotian Shelf exists in two distinct phases, probably indicative of different origins. H. J. McLellan and R. W. Trites Appendix No. 83-E-

OCEANOGRAPHIC FEATURES OF THE STRAIT OF BELLE ISLE The oceanographic features of the Strait of Belle Isle have never been fully described, although tides and tidal currents have been well investigated by the late Dr. W. Bell Davison, Superintendent of Tidal Surveys. The only extensive study of the oceanographic features in the 'Strait was made by the Belle Isle Expedition of 1923. This expedition, under the direction of Dr. A. G. Huntsman, was sponsored jointly by the Biological Board of Canada, the Canadian Department of Marine and Fisheries and the Newfoundland Government. It utilized- the Canadian Government Fisheries Patrol Steamer "Arleux", and the Motor Boat "Prince" of the. Atlantic Biological Station at St. Andrews, N. B. The oceanographic data from this expedition have been analysed with respect to temperature, salinity and density distribution and are at present being prepared for publication. The oceanographic findings are as follows: 1. A minimum depth of approximately 100 metres and a minimum width of 9 miles (14 km.) are limiting factors in the movement of water through the Strait of Belle Isle. 2. Analysis of temperature, salinity and density distributions indicate the water movements at times as follows: (a) A progressive inward movement of water of Arctic and sub-Arctic origin on the north side; (h) A progressive outward movement of Gulf of St. Lawrence waters on the south side; - 156 - (c) A dominant outward flor of Gulf rater; and (d) A dominant inward flow of Labrador rater. The latter condition was not observed during the short periods of observations in 1923 but has been described by other observers. 3. The structure of water columns in the Strait of Belle Isle undergo considerable change with time. The differences in time between the appearance of successive maxima and minima suggest that these are related directly to tidal influences. 4. At times some extreme temperature gradients as between the waters of the north and south side of the Strait were observed as follows: (a) On August 17 the surface temperature gradient was from 3.9° C. on the north to 8.1° C. on the south. (b) On September 7, rhen the dominant flow was outward from the Gulf, the surface temperature gradient was from 4.0° C. on the north to 10.0° C. on the south, while the gradient on the bottom was from less than 0.0° C. on the north to -1.0° C. at the centre of the Strait, and 10.0° C. on the south. 5. Three main water masses are found in various proportions in and adjacent to the Strait of Belle Isle as follows: (a) Gulf of St. Lawrence water from the surface layer with temperature and salinity characteristics of 11.0° C. and 33,3, respectively; (b) Arctic water with temperature and salinity characteristics of -1.6° C. and 33,3, respectively; and (c) West Greenland Current water with temperature and salinity characteristics of 3.5° C. and 34.5A, respectively. In addition other water masses whose characteristics have been in part influenced by land drainage and seasonal - warming are found in traces within the areas covered by the 'survey.

W. B. Bailey and H, B. Hachey

Appendix No. 83-F CUMULATED WATER TEMPERATURES IN THE BAY OF FUNDY AND THE GULF OF ST. LAWRENCE As growth is, in part, a chemical process, water temperatures cohstitute a significant factor in the rate of - 157 - growth of marine animals. Various biological 'investigations now under way, involving growth rates and survival estimates, require a consideration not only of the water temperatures but also of the length of time during which such water temperatures exceed a certain minimum. The average number of degrees of temperature over a certain minimum multiplied by the period during which such excess temperatures are experienced, constitute what are referred to as cumulated temperatures. In the table of cumulated temperatures furnished below for the Bay of Fundy and the Gulf of St. Lawrence, the average number of degrees of temperature is represented by the average monthly temperatures and the time by the number of months. Cumulative Temperatures in Degree-Months (May to October inclusive) Year Area Surface 10 metres 1946 North Rustico 76.0 73.0 Entry Island 71.5 Station 5 55.2 53.6 St. Andrews 66.1 1947 North Rustic° 72.0 65.6 Entry Island 74.0 Station 5 61.1 58.9 St. Andrews 71.4 1948 North Rustic° 78.0 68 0 5 Entry Island 67.1 Station 5 50.3 48.2 St. Andrews 61.3 It will be noted that these cumulated temperatures for the period May to October inclusive are generally and considerably higher in the Gulf of St. Lawrence than in the Bay of Fundy. The marked differences-between one year and another are 'worthy of consideration. L. Lauzier

Appendix No. 83-G SUMMER HYDROGRAPHIC CONDITIONS IN THE NORTHERN SECTOR OF NORTHUMBERLAND STRAIT During the last four summers hydrographie observations have been carried out as part of the program of systematic towing for lobster larvae. The observations have been made at irregular intervals 9 three times a month or more, from surface to bottom at one station off Richibucto, N. B. Compilation and analysis of the data on hand show that: - 158 - 1 - The highest summer maximum temperature of the surface waters was recorded in 1949 as 20.4° C., and the lowest summer maximum in 1950 as 19.2° C. • 2 - The year-to-year variations in the surface temperatures were largest from the middle of July to the middle of August e while they were comparatively small before and after that period. 3 - During July and August the lowest bottom temperature was recorded in 1951, and the highest in 1949. 4 - Temporary abrupt variations of bottom temperatures occurred every year. They suggest oscillations of the thermocline or, in other words, variations in the thickness of the surface layer. 5 - Apparently the thermocline reached the bottom (20 metres) and disappeared during the first part of September. 6 - In a general way an increase of temperature corresponds to a decrease of salinity, the temperature-salinity relationship varying slightly from year to year. 7 - In 1948 and 1949 the surface salinities were consistently somewhat lower off Richibucto than off North Rustic°, on the north side of Prince Edward Island. L. Lauziér

Appendix No. 83-H PRELIMINARY SURVEY OF HYDROGRAPHIC CONDITIONS IN TEE MIRAMICHI ESTUARY AND RIVER IN SPRING 1951 From May 8 to July 4 the water conditions of the Miramichi River system have been studied in relation to salmon investigations. The survey consisted of eight weekly cruises covering five stations from Newcastle to Portage Island. The ratio of the volume of water brought in the Bay and Estuary during rising tide to the volume of water already present there at low water is approximately one to four. • A preliminary analysis of the data brings out the following points: 1 - The salinity stratification was strongest in the vicinity of Sheldrake - andOak Channels, least off Newcastle and intermediate at the entrance of the Bay, near Portage Island. 2 - Off Newcastle the surface salinity reached 7.2A from a minimum of less than 1.0A. On the west wide of . Portage Island the salinity of the surface waters increased from 12.6A to 22.9A. -159- 3 - The highest salinity recorded in the area was 25.7. Waters of.salinity as high as 20.0A were frequently found at the lower depths off Oak and Sheldrake Channels. • 4 - There was horizontal gradient of temperature of approximately 4.0° C. in May, tapering off to 1.5° C. in July, between Newcastle and Portage Island. - The temperature stratification was associated with the salinity stratification. L. Lauzier

Appendix No. 83-I CURRENT MEASUREMENTS IN THE GRAND MANAN CHANNEL Current measurements at a series of stations across the north and south ends of the Grand Manan Channel and across its Northern Approaches were made through complete tidal cycles in early October, 1950. The observations were made with a Geomagnetic Electrokinetograph with which magnitude and direction of surface currents may be determined under way. The data from this survey have now been analysed and reported upon. At the time of survey a system of strong southerly currents was observed on the ebb while flood currents were weaker and less systematic. The residual flow through each section was,southward through the Channel with an average value of 8.6 x 10', cubic metres per tidal cycle. The influence of shore line trends and submarine topograph upon flow patterns could be observed. The southward residual flow is contrary to previous reports for this area so that further observations will be necessary before it can be said whether the observed currents represent normal conditions in the Channel. D. G. MacGregor and H. J. McLellan

4- Appendix No. 83-J • A SURVEY OF WATER CONDITIONS IN THE GRAND MANAN CHANNEL An analysis has been made of data collected between September 18 and 25, 1950, in the Grand Manan Channel. Ob- servations, taken at different stages of the tide along five lines in the Channel end Approaches, gave a fairly complete picture of temperature and salinity distribution. Throughout the Channel area, at all"stages of the tide, vertical gradients of temperature and salinity were very small. In particular, the south-east quadrant was at all times virtually unstratified. - 160 - Tidal motion over the southern shoals, and around prominent points, brings about the vertical mixing which causes this marked homogeneity. Falling tides bring an invasion by mildly stratified waters from the north. No definite pattern of residual flow could be deduced from these observations of temperature and salinity. H. J. McLellan

Appendix No. 83-K . OCEANOGRAPHIC OBSERVATIONS BY R. C. N. SHIPS H. M. C. S. "New Liskeard", carrying out work for the Naval Research Establishment, made nine bathythermograph surveys during the period of July, 1950, to July, 1951. These observations covered the Scotian Shelf, a section to Bermuda, and a section across the Gulf of Maine. The more extensive cruises are plotted in the accompanying diagram (page 161). A total of 912 bathythermograph records were collected during this period, all of which have been processed and filed. W. B. Bailey

Appendix No , 83-L OBSERVATIONS BY THE CANADIAN HYDROGRAPHIC SERVICE During the 1950 season five vessels of the Canadian Hydrographie Service were engaged in making oceanographic observations in addition to their regular survey work. A total of 66 hydrographie stations were occupied, and 348 water samples with their corresponding temperatures were obtained. In addition, a total of 71 bathythermograph observations were made during their work on the coasts of Nova Scotia and Newfoundland and in the Gulf of St. Lawrence. All data have been processed and filed. During the 1951 season five ships were engaged in making oceanographic observations in Canadian Atlantic waters. To date no data are available to report upon the extent of these observations. W. B. Bailey

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The Scotian Shelf showing lines or bathythermograph observations for NL cruises 36, 38, 40 and 47. - 162 - _Appendix No. 83-M WATER REPLACEMENTS ON THE SCOTIAN SHELF In 1949 the Naval Research Establishment, in co- operation with the Atlantic Oceanographic Group, expanded observations of temperature conditions in the water column at the Sambro Lightship off Halifax, N. S. This expansion consisted chiefly of making bathythermograph casts twice daily to obtain the detailed vertical temperature distribution in the water column, and at the same time record the atmospheric conditions. These observations enabled close examination of oceanographical and meteorological conditions and observation of any correlation between them. Drift currents initiated and maintained by the wind are capable of causing widespread replacement of coastal waters. The effect of a north-east wind along the Scotian coast is to pile surface waters along the coast and ultimately to replace the colder bottom waters. This was clearly illustrated at Sambro Lightship in October, 1949 9 when a tropical cyclone moved past the area with the result that the warmer surface waters completely replaced the colder bottom waters. This replacement began on about October 19 and normal conditions did not return until about the 28th. The direction, strength and duration of the wind are factors which enter into this phenomena of water replacements, and govern the extent of such replacements. R. W. Trites

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