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FISHERIES RESEARCH BOARD OF CANADA

PROGRESS REPORTS OF THE PACIFIC COAST STATIONS

PACIFIC BIOLOGICAL STATION NANAIMO, B.C.

AND PACIFIC FISHERIES EXPERIMENTAL STATION 898 RICHARDS STREET VANCOUVER, B.C.

NO. 65

DECEMBER, 1945 VANCOUVER, B.C. These progress reports are issued from time to time to acquaint the fishing industry with some aspects of investigations undertaken by the Fish- eries Research Board of Canada through its Pacific Coast Stations.

CONTENTS

Examination of the Unsaponifiable Matter of Marine Animal Oils. Ill Lyle A. Swain and Betty H McKercher 67 A Mortality in the Fish Life of Quamichan Lake, V.L Ferris Neave 70 The Air-Conditioned Smokehouse - E. P. Sidaway Sockeye Salmon Tagging off the Skeena River in 1945 A. L. Pritchard 77

CORRECTION In an article entitled “Fish Pastes” on pages 38-40 of Progress Reports Xo. 63, a formula for bloater paste given on page 39 inadvertently included as one of the suggested ingred- ients a small proportion (3%) of tomato puree. It has been

drawn to% our attention that the Canadian Food and Drugs Act at present does not allow the inclusion of tomato products in fish pastes, because of the possible misuse of the colouring ability of the tomato products. EXAMINATION OF THE UNSAPONIFIABLE MATTER OF MARINE ANIMAL OILS. III.

The two former parts of this series described this Station’s interest in the unsaponifiable matter (“unsap”) of fish liver oils. This unsap is the portion of the oils that will dissolve in ethyl ether after they have been broken down completely into unsap, glycerol, and soaps. The unsaps consist of mixtures of liquids and solids, and contain the vitamins A and D that were present in the original oil. The method of adsorption (chromato- graphic analysis) used to divide these unsaps into simpler groups of compounds for further study was also described. Part I ( Progress Reports No. 58, pp. 13-16, 1944) gave some results of work on the unsaps and vitamin A content of the liver oils from the sleeper shark , ratfish, monkfish, and marbled sculpin. Part II ( No. 63, pp. 32-34, 1945) described the unsap from dogfish liver oils and showed that an unsap fraction can be secured that contains the vitamin A of the liver oil in about 1 60 of the bulk of the latter. This present account covers the study of the unsaps from the liver oils of lingcod, mackerel shark, soupfin shark and basking shark, and from sperm whale oil. The results differed sharply among these five oils when their unsaps were put through the adsorption process. The accompanying table shows that the proportion of the unsap eluted by each solvent varied greatly with the five oils ; for the lingcod liver oil the results obtained with the unsap from two portions of the same oil sample are given to indicate the validity of the method. The appearance of the unsap fractions eluted by any one solvent also differed from oil to oil, as is described below.

Chromatographic analysis of the unsaps of several marine animal oils.

Unsap from Weight per cent of unsap eluted by Recovery oil, of Oil from % Light Methylene Ethyl Unsap, petroleum chloride ether Methanol %

Lingcod liver 12.2 17 69.1 17.7 7.5 96.0 ( Ophiodon elongatus ) 1.3 70.0 18.8 5.7 95.8 Mackerel shark liver 7.9 1.7 111 4.9 12.1 96.4 ( Isurus nasus ) Basking shark liver 52.2 93.6 4.7 1.5 1.7 101.5 ( Halsydrus maximus ) ‘ Soupfin shark liver 5.7 2.8 40.8 11.9 36.3 91.8 ( Galeorhinus galeus ) Sperm whale 35.8 0.7 88.9 1.0 5.9 96.5 ( Physeter macrocepbalus )

The light petroleum eluates from the unsaps of mackerel shark and basking shark liver oils and from sperm whale oil yielded colourless liquids. As seen from the table, a little over one half of the basking shark liver oil )vas unsap, and almost all of it appeared in the light petroleum eluate. This ls the first unsap examined in this laboratory from which light petroleum 67 elutes a major fraction ; tests showed that this fraction contained a high percentage of the hydrocarbon squalene, which has been shown by others to be present in this oil. The light petroleum eluate from soupfin shark liver oil unsap yielded a white solid, whereas that from the lingcod liver oil unsap was a faintly yellow solid. The fact that the fractions described above are so weakly adsorbed that they escape from the column with light petroleum suggests that they are all of hydrocarbon nature. The material eluted by methylene chloride made up a considerable portion of the unsaps of most of the oils reported here. It contained pigment —yellow in every case, all the cholesterol, and the vitamin A of the unsap. From lingcod and basking shark liver oil unsaps it was solid, probably because it was mostly cholesterol. Mackerel shark liver oil unsap yielded a liquid from early portions of the eluate, and a solid from later fractions indicating that more than one substance was eluted by this solvent. The eluate from soupfin shark liver oil unsap left a liquid on evaporation of the solvent. Calculation showed that it should be 80% vitamin A. Sperm whale oil unsap is known to be chiefly oleyl alcohol, a liquid, with a considerable proportion of cetyl and stearyl alcohols, which are both solid. The fact that almost 90% of this unsap escaped from the column with methylene chloride indicates that these alcohols are eluted by this solvent. The initial portions of the eluate left a liquid residue on removal of solvent, the later ones a solid, implying some separation of oleyl alcohol from the other two alcohols. Ethyl ether eluted only a small proportion of the unsaps of these oils. The eluted material was a yellowish liquid or semi-liquid in every case excepting that from sperm whale oil unsap, which appeared colourless. This is in contrast to the dogfish, ratfish, and sleeper shark liver oils previously reported, where ether eluted the greater part of the unsap, the material being glyceryl ethers. The identity of the material eluted by ether from the unsaps reported here has not yet been determined. The material eluted by methanol had a different appearance in each unsap examined. From lingcod liver oil unsap it was a yellow’ liquid, from mackerel shark a brownish solid, from basking shark a yellow solid, from soupfin shark a brownish liquid, and from sperm whale a colourless liquid. The composition of these products is as yet unknown. Vitamin A is, at the present time, the most valuable chemical occurring in the unsap of fish oils. .It appears in the methylene chloride eluate in this process of chromatography. Of the oils described above, soupfin shark liver oil has been one of the most important sources of this vitamin. The sample examined contained 81,300 USP units per gram. Lingcod liver oil is an important source of both vitamins A and D, containing from 70,000 to 800,000 L'SP units of vitamin A per gram. Mackerel shark liver oil is not commonly produced. The oil reported here contained 25,000 USP units of vitamin A per gram, being somewhat higher in potency than dogfish liver oil. Basking shark liver oil is of low potency, reported as ranging from 0 to 800 L^SP units of vitamin A per gram. Sperm whale oil is also low in vitamin A potency. Of these oils, only basking shark liver oil shows possibility of concentration of vitamin A by chromatography beyond that achieved solely by separation of the unsap from the oil, because in the other oils methylene chloride elutes such a large proportion of the unsap.

68 Sufficient work has now been done to show that the differences in composition of the unsaps of marine animal oils go far beyond variations in content of vitamins A and D and cholesterol , which are the components of the unsap most commonly known . Of the unsaps from the ten oils so far reported, that from basking shark liver oil is outstandingly high in the light petroleum eluate fraction , those from sleeper shark , ratfish , and dogfish liver oils are high in the ethyl ether eluate fraction , and that from soupfin shark liver oil is highest in the methanol eluate fraction . The substances in the unsap occurring in major proportions in the oil (i.e., making up a large percentage of the unsap when it is in turn a consider - able percentage of the oil ) have been recognized in the past . These include cholesterol, fatty alcohols , glyceryl ethers , and squalene . The first two mentioned are of commercial value . Uses have been proposed for the last two but none apparently of great importance . The convenient method of separating these substances which has been outlined in these reports should encourage their re -investigation for new outlets , or make them more accessible for known uses . Substances present in minor proportion may have been overlooked in earlier studies , and uses may be found for them to make their recovery worthwhile . Gratitude is expressed to Mr. J. Hargrove , to the Canadian Fishing Company , to Armstrong Laboratories and to the Technological Laboratory , Fish and Wildlife Service , Seattle , for samples of oils used in this study . The assistance of Miss J. K. Vernon in the laboratory is appreciated . Pacific Fisheries Experimental Station Lyle A. Swain Betty H. McKercher

Quebec Conference Delegates Visit Board’s Western Stations

Following the conclusion of the recent international conference on fisheries and agriculture held in Quebec , several of the delegates from abroad 1 visited western Canada and the United States . Among those interested particularly in Canada ’s fisheries were Dr. Baini Prashad , Fisheries Develop - ment Adviser to the Government of India , who spent several days at the Fisheries Experimental Station in Vancouver and the Biological Station near Nanaimo ; Mr. G. M. Gerhardsen , from the Directorate of Norwegian Fisheries , and Mrs. Gerhardsen ; and Mr. Olaf Notevarp , Director of the Norwegian Fisheries Research Station , Bergen , who was Mr. accompanied by Olav Eidsvik , Chief Mechanical Research Engineer of that Station . Visits were also made to the Vancouver office of the Dominion Department of Fisheries and to representative local fishery industries . 69 A MORTALITY IN THE FISH LIFE OF QUAMICHAN LAKE, V.I.

In August , 1945 , a considerable mortality of fish occurred in Quamichan lake , near Duncan , and attracted much attention among local residents and in the press . On August 20 and 26 members of the staff of the Pacific Biological Station paid visits to the lake in company with Mr. Frank Weir , Provincial Game Warden . The following brief account and discussion of the mortality is based on observations made on these occasions , together with information supplied by Mr. Weir and local residents . Certain observations made in previous years by members of the Station staff were also available for comparison .

The mortality Most of the casualties among the fish population apparently occurred on August 17 and /or 18. On August 18 and 19 immense numbers of stickle - backs ( Gasterosteus aculeatus ) were washed up on the shores of the more southerly part of the lake , in some localities forming windrows containing very many thousands of individuals . A large number of cutthroat trout ( Salmo dark / / ) of various sizes up to about 2i lb. in weight , and some sculpins (Cottus) , had also died . Due to the very warm water temperature prevailing at the time , the fish were decomposing rapidly when the inspection was made on August 20. Subsequently a number of dead muskrats , grebes and ducks were discovered along the shore of the lake . Characteristics of the lake Quamichan lake is roughly two miles long and two thirds of a mile in average wfidth . The depth in most places is less than 25 feet . While the lake is fed seasonally by small streams and is drained by an outlet to the Cowichan river , these watercourses do not function during the dry season . Some of the physical and chemical conditions prevailing at this season can be illustrated by the accompanying table .

Date Depth Temperature Oxygen pH (°F.) (% saturation)

Aug. 22, 1934 Surface 73.8 130 8.5 i t 13 ft. 88 25 ft. 66.6 0 7.0 July 27, 1935 Surface a 75.6 75 7.75 6 ft. 74.8 73 7.75 a 13 ft. 73.8 < < 84 7.7 19 ft. 65.8 48 7.0 Aug. 20, 1945 Surface 79.5 9.88 < < 3 ft. 74.5 123 a 7 ft. 73.6 4 4 15 ft. 71.6

70 Dense populations or “blooms” of algae and other minute forms of plant life occur during the summer. When observations were made on August 20 the water was brown in colour, due principally to an immense population of the small organism Ceratium. Very large numbers of the rotifer Keratella were also present. Discussion Among the conceivable causes of a mortality such as that described, there may be mentioned : (a) an epidemic disease, (b) the introduction of poisonous substances into the water, (c) physical or chemical conditions resulting from natural meteorological and biological events. An epidemic is improbable in view of the fact that all or most of the fish were affected almost simultaneously, and that several different species, with different habits, were involved. . There is no positive evidence in favour of the poison theory. Numerous other forms of aquatic life such as Crustacea and insect larvae, as well as the planktonic organisms, were found to be alive and healthy just after the mortality among the fish. Water taken from the lake at a somewhat later date (September 7) by the Provincial Board of Health showed no toxic effect on mice. On the other hand it was noted as long ago as 1935 ( MS report, Mottley and Carl) that Quamichan and Somenos lakes in summer “possess unstable conditions which are detrimental to fish life.” From the data given above for August 22, 1934, it is evident that at this season peculiar and highly unfavourable conditions may develop. The surface waters become strongly alkaline and supersaturated with oxygen, while the deeper layers show no alkalinity and no appreciable supply of oxygen. On August 20 of the present year an even more extreme condition of alkalinity and high temperature was noted at the surface, and a similar oversupply of oxygen. While apparatus was not available for taking samples at greater depths, it is probable that oxygen depletion was again prevalent. Under these conditions it is obvious that fish life cannot exist near the bottom. Fish would be forced to move towards the surface, where temperature and alkalinity were unfavourably high. Since the lake is very shallow there could at best be only a very narrow zone in which intermediate conditions would prevail. Probably the fish were killed either directly by the unfavourable chemical and physical conditions in the upper layers or by passing rapidly from one to the other of the two contrasting environments. In either case the immediate cause of death would probably lie in respiratory difficulties. It is probable that in many or most years conditions in late summer approach a critical state. This state is produced largely by the heavy development of minute plant organisms which is a well-known feature of 1 this lake. These organisms when living are directly responsible for the high oxygen content of the surface waters and probably the high alkalinity as well. The dead individuals, on the other hand, sink to the bottom and contribute to the organic materials which in the processes of decomposition use up oxygen. Physical factors such as temperature and wind doubtless play an important part in determining whether these tendencies go far enough to produce a lethal condition. Cooling of the surface water, or the action of strong winds, might quickly promote a mixing of the upper and lower layers and result in the disappearance of the dangerous conditions.

71 The deaths reported among birds and mammals were probably not to the same due immediate cause as the mortality among the fish . The decompo - sition of the latter might conceivably have produced ill effects , direct indirect , on the or food of these warm -blooded animals . Alternatively , the casualties among the latter may have been entirely unconnected with destruction of fish life . the Pacific Biological Station Ferris Neave

Continuous Processing of Canned Fish

The cooking and sterilizing of canned fish in British Columbia canneries is carried out by a batch process under pressure in steam retorts , and sometimes constitutes a “bottleneck ” in the mechanical operations that are otherwise practically continuous when the cannery is operating . More- over , the cans undergo several handlings . In discussions between Dr. C. R. Elsev of the B.C. Packers Ltd ., Dr. N. M. Carter , Director of the Pacific Fisheries Experimental Station at Vancouver , and Mr. F. E. P. Griggs of the Canadian Hanson and Van Winkle Co. of Toronto , manufacturers of de-greasing equipment , there arose the suggestion that the latter companv might undertake the design and development of equipment suitable for the continuous cooking and sterilizing of canned fish . One of the solvents used for de-greasing is a non -inflammable , non- corrosive organic liquid boiling at 245° to 248°F., just slightly higher than the temperature in the steam pressure retorts employed on this coast in fish canning operations . Trials performed by Mr. E. P. Sidaway of the Experimental Station , using an experimental unit expressly constructed for the purpose and supplied by the Toronto firm , have demonstrated that sealed cans of fish immersed in the vapour above this liquid when it is actively boiling can be cooked and sterilized to yield a product equal in quality to that of fish processed in the usual way. The temperature of the hot vapour remains constant with no necessity of regulation as long as the liquid is kept boiling at a sufficient rate , and loss of vapour is negligible. The solvent action of the condensing vapour removes all oil and grease on the cans and leaves them clean and bright so that they do not require subse - quent washing . Rates of heat transfer from the vapour to the cans were investigated by processing trial cans into which were inserted thermocouples that registered on a chart the temperatures within the can contents. Further studies of these rates are under way . Since the cooking unit is not tightly closed , there is no external pressure corresponding to the steam pressure in a retort to compensate for the above -atmospheric pressure developed in the sealed cans . In no tests, however , did the temporary strain on the cans cause any signs of leakage in the seams or seals , and the contents remained sterile after storage at room temperature .

The Canadian Hanson and Van Winkle Co. is now designing a unit for commercial trial of continuous processing of cans at the rate at which they come from the can -closing machine in a cannery . 72 THE AIR-CONDITIONED SMOKEHOUSE

A considerable proportion of the fish landed in Canada is marketed as smoked fish . In 1941 , for instance , about 17,000 ,000 lb. of ocean fish was so processed , and in 1942 about 18,000,000 lb. These figures refer only to fish sold as smoked fillets , etc., and do not include large quantities smoked tor canning. Mild cured salmon , although not listed as smoked fish , is generally sm oked before it is sold at retail wThile a considerable amount of the catch of lakefish , as for example the Winnipeg goldeye , is smoked . In spite of the magnitude of the smoked fish industry , with a few exceptions , Canadian producers are still using the old fashioned type of upright kiln . These are towering structures of narrow cross section , often running up through two, three or more stories of the building . Circulation is maintained entirely by means of natural draught , which factor determines their peculiar design , and is controlled by means of adjustable dampers in the roof . Fish is suspended from racks or tenters which rest on cleats on the walls and the fire of sawdust and chips or hardwood logs smothered with sawdust is kindled on the floor , usually in a pit beneath the main part of the kiln . Occasionally steam coils may be used to augment the heat produced by the fire and a recent improvement adopted by some fish smokers is the use of steel or wooden trucks wrhich are loaded outside and then run on rails into each section of the smokehouse . Another innovation is the use of wire mesh trays in conjunction with trucks . The general principles of smoking , however , remain unaltered . These tall kilns have many disadvantages . In the first place their great size makes construction expensive since they are built usually of brick or hollow tile . They take up much valuable space within the plant , but owing to the long time required for smoking the large size is unavoidable . The time required for smoking various products may range from 12 to 48 hours or more , some varieties of smoked fish being cured for many days . Long periods of smoking have deleterious effect on the product in many instances . Heavy black cod , for instance , hanging in air whose temperature is especially favourable for the growth of bacteria , may become tainted in the thick portion near the bone . Although this condition may not be immediately apparent to the producer , a prejudice against it may be established in the mind of the consumer who buys such a piece of fish . Heat input in most cases is derived entirely from the fire , and air circulation within the house depends on the state of the fire , the the height of building and the weather . Temperature and humidity may be controlled to a certain extent by the operator through his fire and dampers , but it is not possible to measure either accurately and few attempt to do so. Thus in cold weather the house temperature may be lower than while is desirable ; in summer , when outdoor temperature and humidity are excessive often , curing may be impossible as the fish soften and drop on the floor . Moreover , the fish at the top of the kiln colour and than cure much more slowly those nearer the fire , making it difficult to obtain a uniform product from day to day.

73 I

In the tall kilns sudden opening of the doors may cause showers of ash a to fly up from the fires and adhere to the fish. Loss due to flying ash and ’ dropped fish by smokers using this type of kiln may run into thousands of pounds annually. During the past decade engineers in many parts of the world have given their attention to the problem of overcoming these difficulties in producing smoked fish and some satisfactory smokehouses have been designed. These are usually referred to as forced-draught, air-conditioned or controlled smokehouses, but the general principles involved are essentially the same. 1 It has been shown that the rate of smoking as judged by development Æ of colour or measured by deposition of phenols is a function of the velocitv of the air—smoke mixture past the fish. To achieve a high velocity fans are ' used which may be variously situated, but which all produce a similar effect, n The appearance of the smoked surface in most smoked products is improved H by curing at a higher temperature than that usually maintained in the commercial type of kiln. When the brined fish is subjected to a temperature of 90°F., a thin glossy pellicle forms on the cut surface which not only gives m it an attractive appearance, but may serve other useful purposes. To obtain a a temperature of 90CF. it is usually necessary to supplement the smoking fire with electric or steam heaters to warm the incoming air-smoke mixture. This type of auxiliary heating moreover permits close control of temperature thermostatically. Where high summer temperatures prevail proper condi- tions for smoking within the kiln may be obtained by passing the air through an ice-box or over refrigerated coils before it enters the heater. In this way excess moisture is removed from the incoming air, which enters the kiln at the desired elevated temperature and with an increased capacitv for removing moisture from the fish. Obviously in a smokehouse of this design the smoke-producing fuel must be burned outside the smokehouse and several types of smoke producers have been designed for this purpose. Here again it is necessary to have as complete control as possible over burning of the sawdust. If the fire is allowed to become too hot beneath the sawdust, excessive distillation takes place and the fish becomes bitter to the taste due to the deposition of volatile acids. The best fire is one which has combustion confined to the surface and which has a large burning surface. This produces a large volume of cold “dry” smoke. Having obtained all the above conditions, that is, a mixture of the proper kind of smoke with air of optimum temperature and relative humidity passing through the house at the optimum velocity, it remained only to insure that all the fish in the charge was subject to the same conditions. This is accomplished by using baffles or air foils which straighten out and direct the flow of air into every part of the actual smoking chamber. An alternative method is to cause the fish to circulate through the kiln con- tinuously during the smoking period. Air-conditioned smokehouses embodying all these various features have been designed at both the Atlantic and Pacific Fisheries Experimental Stations of this Board ( Progress Reports of the Atlantic Coast Stations, No. 34, pp. 10-14, 1943 ; also Progress Reports of the Pacific Coast Stations, No. 40, pp. 15-16, 1939), at the Torry Research Station in Scotland, in Australia and in the United States. A few commercial smokehouses built in accordance with some or all of these principles are in operation in the

74 i United Kingdom , the Canadian Maritime Provinces and in the United States , those in the latter being used principally for smoking meats ; but so far on the Pacific Coast , with one or two exceptions , the old fashioned methods still prevail. No attempt will be made in this report to set forth detailed descriptions ,,f the smokehouse designs referred to, this information being available on application . The purpose of this report is to point out the reduction in smoking time which may be obtained by using an air -conditioned kiln which makes possible a higher turnover per cubic foot of space and a better quality , more uniform product . In addition , positive control of temperature and humidity , ease of operation and elimination of waste through fly ash , dropped fish and over -smoking , are valuable features . An air -conditioned tunnel operating on the principle of circulating the hsh was constructed at this Station some three years ago to carry out investigations on both smoking and dehydration of fish (this series of Progress Reports , No. 56, pp. 4-5, 1943 ). Since then it has been used success - fully’ in producing a great many types of commercial smoked fish products . A comparison of the time required to smoke these products with the average time taken in commercial kilns is shown in the accompanying table .

Average smoking time in hours Variety Commercial smokehouse Air-conditioned smokehouse

Kippers 12 - 15 4 - 6 Black cod fillets 12 - 24 4 - 6 Grey, ling and red cod fillets 12 4 - 6 Salmon ( smoked ) 12 - 15 5 Salmon (liardsmoked) 48 10 12 ( kippered - Salmon ) 7 - 13 3 - 6 Anchovy (for canning) 5 - 6 è - 1

In addition to the more common products listed above , many other species of fish not commonly smoked have been treated experimentally with good results . These include flounders (dressed and skinned or filleted ), sea perch , bass , pilchards , hake , soupfin , eulachons , oysters and clams . Four species of lake fish , namely tulibee , jackfish , yellowjack and mullet , were experimented with at the request of the Manitoba Industrial Develop - ment Board and it was found that all these could be dealt satisfactory with in a manner using a procedure similar to that used for such fish as lingcod and grey cod .

Precanning treatment of fish with smoke calls for a very light smoking * as the flavour and colour are greatly intensified by heat processing subsequent and storage . Experiments conducted with salmon , herring and anchovy indicated the following times as giving the best results equipment . with this

s Species Smoking time (hours) .. Salmon 2 Herring S - 1 Anchovy h - 1

75 Details of smoking time for the other types of controlled smokehouse mentioned are not available except for the Halifax model, fSome typical processing times are: Cod fillets and kippers 2 hours Herring fillets for canning, 15 - 20 minutes It may be assumed, however, that for all types of air-conditioned smokehouses processing times are about the same, the limiting factors being smoke and air velocity, temperature and smoke density. Detailed descriptions and drawings of the air-conditioned smokehouses mentioned may be obtained from the following places : Torry Research Station, Aberdeen, Scotland, Atlantic Fisheries Experimental Station, Halifax, N.S., Pacific Fisheries Experimental Station, Vancouver, B.C., and through the U.S. Fish and Wildlife Service, Dept, of Interior, Washington, D.C. Pacific Fisheries Experimental Station E. P. Sidaway

Vancouver Station Holds Exhibit of Activities

On Friday, December 14, the Pacific Fisheries Experimental Station at Vancouver threw open its laboratories for an informal exhibition of its work- on fisheries technology. The fishing industry as a whole, together with representatives of local fishery publication firms, were invited to attend and the response was most gratifying. Exhibits of equipment and processes pertaining to investigations on refrigeration, insulation, canning, smoking, dehydrating, curing, specialty products, nutritive value of fish flesh as determined by feeding tests with a white rat colony, bacteriology and plant sanitation, chemistry and vitamin content of fish liver oils, products from seaweed and kelp, and preservation of fishing nets were on display, adequately described by placards. Members of the staff were asked many pertinent questions concerning further details of the work.

On the preceding evening, the annual “laboratory display night” of the British Columbia Academy of Sciences was held at the Station to allow members and friends of the Academy to acquaint themselves with the types of investigations being carried on. Later, a group from a young people’s organization viewed the display from its educational standpoint. 76 SOCKEYE SALMON TAGGING OFF THE SKEENA RIVER IN 1945

During the season of 1945 , the salmon tagging programmes in Northern I gritish Columbia were expanded to include all five species while still , maintaining special emphasis on the sockeye . Two vessels were employed instead of one as in 1944 . The first of these , the "Estep" under Captain \\ Lovrich , worked offshore in the neighbourhood of Dundas , Banks , Stephens , and Porcher islands and in Hecate strait from June 2 to 25. The " , operations second, the " Lady V under Captain Wm. Leask restricted its niainlv to the mouth of the Skeena river off Inverness passage , Smith and Kitson islands , with one side trip to the Nass area and one to Principe channel. The recoveries to date from the sockeye salmon experiments are presented and discussed briefly herein . “OFFSHORE” TAGGING In spite of the most conscientious effort and application on the part of the crew of the "Estep" and the tagger , offshore tagging was a virtual failure . This lack of success can be attributed mainly to the fact that the salmon do not appear to show or to concentrate in sufficiently large schools to make purse seining profitable . In addition , the weather conditions during June were extremely bad with frequent winds and heavy rains , thus greatly limiting the operations . Only 26 salmon were tagged , as follows : sockeye — 13 ; spring —9; coho 4. Two recoveries have been made . One sockeye tagged in Ogden channel— moved into the mouth of the Skeena in six days , and one coho from Beaver pass was recaptured in the Ecstall , a tributary of the lower Skeena , in four days . The returns , though limited , are important in demonstrating for the first time that salmon entering the Skeena river may use channels south of Edye pass which was set as the boundary from the experiments in 1944 . “INSHORE” TAGGING In discussing the inshore tagging experiments , the numerous tagging localities are grouped under three headings : Nass area including Steamer passage , Boston and Compton islands ; Principe channel area including End Hill , Mikado bay, and Mink Trap bay , and Skeenariver mouth area including the waters off Inverness passage , Smith and Kitson islands . The following numbers were tagged and returned in each : Nass area— 71 and 20 (28.2 % ) ; Principe channel area—513 and 12 (2.3 %) ; Skeena river mouth area—2,212 and 773 (34.9 %). Nass Area All the recoveries obtained thus far from the Nass area tagging were from the commercial and Indian -food fisheries . Particularly interesting in their implications are the records of three fish which eventually found their way to the Skeena : one to Carlisle bar , one to Point Lambert , and one to Moricetown about 22 miles east of Hazelton . Such recoveries indicate the of the k difficulty of definitely separating for statistical purposes the catches Xass and Skeena district into fish bound for one or other of the rivers . Principe Channel Area The returns from the Principe channel tagging were even more local in their distribution than those from the 1944 experiment . Five were retaken in the Mink Trap bay fishery and seven on the spawning grounds above Mink Trap lake . Skeena River Mouth Area Total percentage recoveries. The recoveries from the tagging in the Skeena river mouth area may be divided as follows : commercial fishery — 563 77 1 ( 25.5% ) ; Indian-food fishery—198 (9.0% ) ; spawning grounds—12 (0.4% ) The total percentage recoveries must be considered as minimal figures for exploitation because many factors operate to keep down the number of returns. These include such things as loss of tags due to improper tagging loss in tags being retaken but not returned, etc. Since, however, conditions were relatively similar in 1944 and 1945, general comparison between the two years may be made to show that the average exploitation by the » commercial fishery was lighter in 1945 (25.5%) than in 1944 (41.0%), and that by the Indian fishery heavier, namely, 9.0% as compared with 6.9%. Of the total recaptured in 1945, the Indians took 26.0% as opposed to 14.4% in the previous year. Variation in percentage recovery. In the accompanying table are presented the numbers of sockeye salmon tagged each week throughout the summer together with the numbers and percentages later recovered from the commercial and Indian-food fisheries.

Numbers of sockeye salmon tagged each week, number of returns made later from the commercial and Indian-food fisheries, and percentages which these returns constitute of the total tagged, for the Skeena river mouth area during 1945.

Number Recoveries, percent Recovered of total tagged Week Number Tagged Cominer. Indian Commer. Indian fishery fishery fishery fishery June 19 to 23 381 45 43 11.8 11.3 June 24 to 30 614 108 67 17.6 10.9 July 1 to 7 208 82 16 39.4 7.7 July 8 to 14 390 143 39 36.7 10.0 July 15 to 21 409 126 23 30.8 5.6 July 22 to 28 111 32 7 28.9 6.3 July 29 & 30 99 27 3 27.3 3.0 2212 563 198 25.5 9.0

The percentage recoveries for the commercial fishery from those fish tagged up to June 30 (11.8 and 17.6) are definitely lower than those from the tagging after July 1 (ranging from 27.3 to 39.4). There is no doubt that this difference is due to the postponement by the fishermen of the commencement of the sockeye fishing season from Sunday night, June 24, to Sunday night, July 1. Thus during what would normally have been the first seven days of the sockeye season, only spring salmon fishermen operated with large nets of over 6J inches stretched mesh. The percentages taken by the Indian fishery from fish tagged up to June 30 were 11.3 and 10.9. From those handled after July 1 the figures ranged from 10.0 to 3.0 and demonstrated a gradual decrease as the season progressed. This heavy exploitation by the Indians of the early runs, followed by a steady decrease throughout the summer, may be the usual condition which is caused by a desire to procure food supplies as soon as possible. On the other hand, the possibility must not be overlooked that the early increase in 1945 could have been due in part to the presence of relatively more sockeye at the capture stations as a result of the lowered intensity of the commercial fishery. Although there is little hope of attaining absolute accuracy, it is interest- ing to consider the effect of the unexpected “economic” restriction between

78 Tune 24 and June 30 on the size of the commercial catch and the escapement . That the salmon were already in the lower river in an abundance not greatly different from that later in the season , is proved by the numbers obtained for tagging by the seine boat which operated in a similar manner throughout the season . It is thus not unreasonable to assume that about 700 gill -netters could have taken during the week in question at an absolute minimum 200 ,000 sockeve salmon . This number would presumably be represened by an exploitation of 33.6 %—the average for the fish tagged after July 1. Actuallv onlv 16.4 %—the average for fish tagged up to June 30—was taken . Thus 17.2 33.6 x 200 ,000 , or about 102 ,000 over and above what might be called the expected normal escapement , proceeded upriver . In calculating the numbers from this group which eventually reached the spawning beds , some compensation should be made for the possibility that the Indian fishery was heavier because of the presence of relatively larger numbers of fish . The maximum reduction should be the difference between the percentage recoveries for fish tagged from June 19 to June 30 and those handled from July 1 to 14, or about one quarter . The minimum extra escapement thus becomes about 75,000 sockeye on the assumption of a catch reduction of 102 ,000 fish or 9 to 10 thousand cases . That the extra escapement did not concentrate in one district upriver is amplv proved by the distribution of the recoveries in the Indian fishery and on the spawning grounds . For sockeye tagged between Tune 24 and 30, areas as widespread as Moricetown , Kispiox and Babine were represented in the recoveries in approximately the same proportions as were usual for the remainder of the season . Migration time between areas. The time taken for the sockeye to move from the point of tagging to the locality of recapture , as calculated from the dates of recovery submitted , is subject to evident errors , but certainly must be considered a maximum . On the average the sockeye remained in the lower reaches of the Skeena up to the eastern end of DeHorsey island for 6.6 days . They reached Point Lambert in an average of 5.3 , Terrace in 10.7 , Kitselas in 12.1 , Kitwanga and Skeena Crossing in 16.0 , Hazelton and Kispiox in 18.4 , Babine lake in 38.1 , and Moricetown in 22.2 days . Compared with 1944 , this year ’s migration is considerably slower . This change is most probably due to the much lower water in the rivers during most of the summer of 1945 . Distribution of fresh-water recoveries. The recoveries from the Indian fishery and the spawning grounds , much more numerous this year , show that , with one possible exception , the runs to the various rivers were mixed throughout the season . In the Lakelse district all five tagged fish were from the part of the run before June 29. The commercial fishery , which actually not did start until July 1, could thus have had little effect on the size of this spawning population . ACKNOWLEDGMENTS Realizing the extra effort and conscientious application which was made in carrying out these experiments , the writer wishes to acknowledge the work of " Captain Lovrich and the crew of the " Estep, Captain Leask and the crew " " of Lady V., and the taggers — Messrs . H. D. Fisher , J. A. McConnell and G. Walther . The fishermen , fishing companies displayed and fishery officials again sincere interest and gave most necessary and valuable help . Pacific Biological Station A. L. Pritchard 79