T International Council for CM 19~/K:l The Exploration of the Sea Administrative Report

SHELLFISH AND BENTHOS COMMITTEE • by J. E. Stewart 1976 MOLLUSCA AND BENTHOS BELGIUM (Reporting on Crustacea Only) Canada

(J. E. STEWARTt

Crassostrea virginica Oyster population assessments were carried out in Caraquet Bay, Prince Edward Island, and the Miramichi River estuary in New Brunswick to monitor changes in structure and standing crop, to forecast future conditions in the fishery, to recommend changes in exploitation procedures and to determine potential for the implementation of management procedures such as resource enhancement. Efforts to expand and re-habilitate Maritime oyster stocks included: - the cleaning, prior to spatfall, of approximately 24 hectares of oyster bottom in Caraquet Bay in order to improve recruitment and expand the population. Several small yet formerly productive oyster beds in Prince Edward Island were also cleaned and stocked with 22 metric tons of broodstock. - a co-operative resource enhancement operation with Prince Edward Island Fisheries resulted in a total of 7 hectares of new oyster ground being developed in the Dunk and Wilmot Rivers of Summerside Harbour. This was done by relaying 181 metric tons of oyster stock from overcrowded areas of the natural bed and planting them on good but presently unstocked areas of bottom. The effect is twofold: increased production acreage is being developed and oyster quality and hence price per unit is increased by the thinning. Placopecten magellanicus Research on this species in Newfoundland has been primarily on problems relating to its culture. Larval settlement and survival are being examined to further our understanding of resource enhancement possibilities. - 2 -

A study is also underway to determine peak settlement times. When comp1eted, this study shou1d e1iminate the guesswork invo1ved in deciding the best time to set out co11ectors. New co11ecting materials and various modifications in ~ the design of co11ectors are also being examined. Growth characteristics of anima1s in suspended cu1ture as we11 as in bottom cu1ture are being investigated. Georges Bank Increased 1andings of 7,480 and 9,709 M.T. of shucked meat in 1975 and 1976 respective1y (compared with an average of 4,476 M.T. from 1970 to 1974) appear to ref1ect the beneficia1 impact of regulations on 1anded meat size (adductor musc1e), which were first introduced in 1972 and put into effect by the Canadian participants in June, 1973. The Canadian fishery at present accounts for approximately 85% of the 1andings from the bank. The regulation, which now specifies that no more than 5% of the samp1es taken from the 1anded catch must contain meats sma11er than a mean size (11.3 gm) equivalent to 40 meats/lb., has been progressive1y lowered annually together with a freeze in fleet size, is a beginning towards imp1ementation of ICNAF recommendations in 1972, namely that, on a yield/ recruit basis, a 34% increase in yie1d will resu1t from an increase in age at first capture from age 4 (rough1y 48 meats/1b) to age 5 (roughly 32 meats/1b). Bay of Fundy • Dec1ines in this fishery due to long-standing effects of overfishing since the 1930's have been documented in papers presented at ICES in previous years. Oscil1ations in fleet size in response to periodic fluctuations in scal10p abundance (whose timing appears to be related to long-term environmental fluctuations), have undoubtedly contributed to the wide amplitudes of annual catch fluctuations, and an attempt was made to stabilize the fishery in 1972 by introducing limited entry. A freeze in unused licenses has been introduced this year to implement recommendations for further cuts in overall effort. Chlamys islandicus Resource surveys of the distribution and abundance of this species were conducted a10ng the northwest slope of St. Pierre Bank, in the northeastern Gulf of St. Lawrence and off Nain in Labrador. None of the 1009 scallops tagged in the Gulf in 1975 were recaptured this year. A tagging programme has also been initiated on St. Pierre Bank. Il1ex illecebrosus Squid were p1entiful in inshore Newfoundland waters during 1976, and landings increased from 3202 metric tons in 1975 to 9869. Biological sampling of the commercial catch was continued and staff participated in a research cruise from Nova Scotia to Delaware by the Institut Scientifique et Technique des Peches Maritimes of St. Pierre &Miquelon. Studies into squid population biology will be continued in 1977. - 3 -

Mya arenaria Assessments of soft-shell clam stocks in P.E.I. to determine their potential for hydraulic harvesting were carried out in cooperation with the P.E.I. Department of Fisheries. Approximately 15 estuaries were surveyed and stocks totalling 1,134 metric tons of market size clams were identified. Studies on the recruitment, meat quality, and growth pattern of these populations are continuing. In addition, a study was initiated in Fortune Bay, P.E.I. to assess the short- and long-term effects of hydraulic harvesting on soft~shell clams and their habitat. Effects on the stocks themselves (growth, recruitment, condition, etc.), on the benthic fauna and on the substrate are being monitored. Analysis of the initial data is underway but the study will require four to five years for completion. This study will contribute greatly to the development of a sound management policy for clam stocks. Spisula solidissima An assessment was made of available information on surf clam stocks in the southwestern Gulf of St. Lawrence in response to industry enquiries. The review revealed few biologically sound surveys and suggested the need for • systematic surveys to determine the level and value of these stocks. Mytilus edulis Mussels are being analyzed for their polychlorinated biphenyl, hexachlorobenzene, myrex, Hg, Pb, Cd, Zn, Cu, As and Se content. Chondrus crispus Chondrus crispus is harvested in large quantities in the Maritime provinces by either handraking (southwestern Nova Scotia) or dragraking (Gulf of St. Lawrence). The mean standing crop in the commercially important beds in southwestern Nova Scotia and western Prince Edward Island per 0.25 m2 was 109 9 and 26.3 9 respectively. A study on the ecological impact of the traditional harvesting techniques was undertaken. The handrakes removed approximately 26% immature Chondrus crispus plants while the percentage in the harvest of the dragrakes was 58%. The percentage of the handraked harvest attached to holdfasts was • 5% whereas that of the dragraked harvest was 33%. Similar studies were carried out in western Prince Edward Island on two different versions of the dragrake. It was shown that the basket­ dragrake was significantly more damaging to the C. crispus population. - 4 -

Lobsters (Homarus americanus). occupy the f. crispus beds in western Prince Edward Island and it has been shown that their incidental harvest along with f. crispus varies with season and location. Mean lobster capture per hour ranges from between 1 and 30, and the percent injured. from a subjective inspection only. ranges up to 25%. Studies on the growth of f. crispus were undertaken in both the above mentioned areas in the latter part of 1975. Growth appears to be slow; plants 15 months old have a maximum length of only 4 cm and have developed 3 dichotomies. However, between November and February growth appears to have been exponential. Shellfish growth, Productivity A program to develop indices of production potential of Maritime inlets was begun during the summer of 1974. Initial trials have concentrated on the development of holding systems which would be suitable for a variety of species. In the initial experiment three bivalves (mussels. Mytilus edulis; soft-shell clams, Mya arenaria; and razor clams, Ensis directus) were placed near Luke Island in St. Margaret's Bay. Trays of cylindrical containers successfully maintained the two clam species over two winters and virtually eliminated the mortalities due to predator pressure evident on nearby beaches. The soft-shell clams attained a mean shell length of 40 mm in two seasons. The razor clam experiments were less successful since these mobile molluscs were capable of escaping from the containers. Mussels were successfully held in suspended culture on ropes for two years although drift ice and storms resulted in the need for constant maintenance to the support system. Also, the relatively unprotected mussels suffered some losses from starfish. Despite these problems, the mussels grew to more than a minimum commercial size within two growing seasons. Production indices for different environments cannot be based on growth and mortality measurement for indicator species unless it can be assured that differences due to inherent physiological (genetic?) influences among the stock specimens can be distinguished from those due to environmental effects. Earlier work with mussels in Bedford Basin and St. Margaret's Bay gave assurance of major bay-to-bay differences in production parameters but gave indications as well that there were different growth "strains" within the • single stock used. Accordingly, experiments were be gun in 1976 to more critically examine these anomalies. - 5 -

Benthic, community Dynamics Measurements of organic carbon, nitrogen and total organic matter in surface sediments in Bedford Basin are maximum in locations where changes in steep bottom gradients occur. High concentrations at the base of steep slopes suggest that accumulation could be due to downslope trans~ort caused by erosion from currents which meet the bottom at these depths. Profiles of organic content indicate that vertical gradients occur in'sediment from depositional areas in deep water. Cores from regions of slope gradient change contain approximately equal amounts of organic matter throughout the upper 10 cm. Physical mixing of sediment through current-induced water . movement and animal burrowing could homogenize sediments in areas where accumulations occur. Man-made organic compounds (DDT and its metabolites) occur in benthic invertebrates, demersal fish and sediments taken from St. Margaret's Bay, Nova Scotia. Total DDT levels in whole organisms, excluding lipid-rich tissues, grouped as benthic epifauna, infauna, and demersal fish were not significantly different and thus no accumulation occurs in th~s food chain. Adenosine tri phosphate (ATP) content in sediments from various intertidal and sublittoral areas is being measured as an index of meio- and microfauna and flora biomass. Recovery efficiencies of extractions in O.lm boiling NaHCO with crystalline ATP added to sterile sediment range from 40-60%. Comp~risons between ATP concentrations with depth in sediment and between cores taken within 1 m2 are being made with oxygen consumption by the undisturbed sediment cores and macrofauna biomass.

Finland (J. Lassig)

Benthos At the Institute of Marine Research no samples were taken in the open sea in 1976, because the research vessel was docked far rebuilding. In co-operation with Tvarminne Zoological Station studies on benthic macrofauna were continued in May, July and September in the a~chipelago • of Tvarminne. The National Board of Waters in co-operation with the Archipelago Research Institute of the University of Turku carried out routine control analyses in coastal waters of SW Finland at about 100 benthic sampling stations. The influence of industrial pollution on the camposition of benthic fauna was also studied off Pori in the Bothnian Sea and off Kokkola in the Bothnian Bay. - 6 -

At the Institute of Radiation Protect;on benthos studies were carried out in the vicinity of two nuclear power plants. Samples have been taken once at 9 stations offLoviisa in the Gulf of Finland, and twice at 7 stations in the archipelago of Rauma in the Bothnian Sea. At the Water Conservation Laboratory of Helsinki City macrobenthos studies were continued monthly during the ice-free period at one station off Helsinki, and 3 times at five stations off Espoo. At the Tvarminne Zoological Station of the University of Helsinki macrofauna studies were continued at 14 stations in the harbour of an iron mill in the vicinity of the research station. Meiofauna studies were also continued on a soft bottom. At the Archipelago Research Institute of the University of Turku population dynamics of Mesidotea entomon (Isopoda) were studied. The biology of Polydora redeki (Polychaeta) was also studied. At the Huso Biological Station of Abo Akademi macrobenthos samples • have been taken at 20 fixed stations in the Archipelago of Aland. Effects of artifical wave exposure of ferry traffic on zoobenthos and phytobenthos have been continued. At the University of Oulu studies on benthic macrofauna were continued. in the Bay of Liminka.

France (J. Audouin) Mollusques Ostrea edulis _ les observations concernant 1 'eqizootie qui frappe 1 'hu1tre plate ont etepoursuivies. On a note une legere extension de la maladie. Cependant, les baies largement ouvertes restent indemnes. Quel que soit leur ~ge ou leur origine, les huftres plates initiale­ transf~r€es • mentexemptes de parasite qui ont ete dans des zones contaminees ont ete reconnues sensibles a Marteilia refringens. Crassostrea angulata ~ 1'etude des mortalites massives de ~. angulata (1970-1973) dont l'etiologie n'avait pu ~tre precisee a et~ reprise. Un virus a ete mis en evidence lors de 1'examen du materiel fixe a 1lepoque des mortalites. 11 est a l·origine des lesions qui avaient ete constatees chez les huitres malades. - 7 -

Crassostrea gigas 1es etudes sur 1a reproduction, 1e captage et 1 1 e1evage ont ete poursuivies. Dans 11ensemb1e, 1es resultats du captage ont ete inferieurs a ceux de 1975. Mytil us edu1 i s une etude sur 1a croissance (bouchots de La Vi1aine) a ete entreprise. Pecten maximus 1'etude des stocks de Coqui11es Saint-Jacques a ete poursuivie sur 1es principaux gisements du littoral francais. Des essais de captage ayant entrain~ des resultats variables ont etemenes dans divers secteurs. Chlamys varia des resultats favorables ont ete obtenus lors des operations de captage rea1ises en 1976. Programme 1977 Etude des stocks de mollusques et de leur dynamique. Poursuite des travaux sur la genetique, la reproduction, le captage, la croissance et la pathologie (contribution a 1a survei11ance et au controle des ma1adies ainsi qu1a 1a se1ection diespeces et d' individus resistants)

Federa1 Repub1ic of Germany (K. Tiews) Molluscs Mytilus edulis Experiments on the raft culture of musse1s at the Institut fur Kusten- und Binnenfischerei were discontinued in the western Baltic (Flensburger Forde). Oysters Raft and container culture experiments with Crassostrea gigas were continued at various localities of the Wadden Sea off the German North Sea coast and in the western Ba1tic at the Institut fur Kusten- und Binnenfischerei. - 8 -

Cockles Cockle beds along the coast of Niedersachsen and Schleswig-Holstein were again surveyed by the Institut fur Kusten- und Binnenfischerei. A commercial fishery, which started in 1973, was continued off the coasts of Niedersachsen and of Schleswig-Holstein. Benthos The Biological Station of Heligoland continued its sampling of benthic communities on special stations in the North Sea with the aim of studying changes in species distribution and dynamic aspects of the eco-system. The Institut fur Meeresforschung at Bremerhaven has continued its study of the distribution cf microbenthos in the southern North Sea with special emphasise on nematodes, fungi and bacteria. The Institut fur Meereskunde continued its studies on the availability of benthic food specimens in relation to their utilization by fish in the Kiel Bight. Iceland (Not Reporting) • Ireland (C.B. Duggan and F.A. Gibson) The time and abundance of pectinid spat settlement (Pecten maximus being of chief interest) was again investigated in a sea lough on the south coast (L. Hyne), using artificial collectors suspended at different depths. Netherlands (P. Korringa) Moll uscs Ostrea edulis The special control on the occurrence of the "Aber disease" caused in flat oysters by the haplosporidian parasite Marteilia refringens was • continued in 1976. As in the years, before the control was split in two parts; one to advise the oyster farmers for their purchases based on analyses of samples from France and of consignments consequently arriving in The Netherlands, the other to estimate the character and spread of the disease after relaying in the Oosterschelde based on analyses of oyster samples taken from the plots. - 9 -

In total 163 samples destined for importation from France were analysed histologically, offering a selection of 112 infection-free lots. In 32 cases lots were refused, based on too high a level of infection, whilst 19 lots with low infection rates (less than 10% of the oysters bearing the parasite) were permitted on the beds to be submitted to special attention during the culture period. The results of the analyses showed that the character of the disease was for 1976 the same as in the years 1975 and 1974, which means no abnormal oyster mortalities and no spread of the disease on the oyster plots in the Oosterschelde. This is in glaring contrast with the violent and spreading character of the disease in France (Brittany) and Spain. In the Grevelingen, now a tide-free sea water lake created by dike building, spatfall of the flat oyster occurred quite unexpectedly. The numbers of oyster spat were high in relation to the very small number of adult oysters, thanks probably to the absence of strong currents and/or the lack of predators. Attempts are being made to create a new centre of oyster culture in the Grevelingen, especially for providing the Oosterschelde plots with broodstock. Forthis purpose collectors have been placed in the Grevelingen. • Both mussel shells and plastic collectors of the type used in the Rade de Brest caught a fair number of spat. Mytilus edulis The sanitary control of the Dutch shellfish areas and oyster basins was continued. The results were very satisfactory. In the western Wadden Sea there was at the end of the month of September some slight evidence for the presence of enteric shellfish toxin. A small consignment of spat produced in the hatchery of Whitstable (U.K.) was placed on trays in one of the basins of the Mussel Experimental Station on the Isle of Texel to study growth, su~vival rate and rearing costs. Research dealing with cleansing and storage of marketable mussels was continued at the Mussel Experimental Station on the Isle of Texel. Important for the future of the mussel industry was the governmental decision to close the Oosterschelde with a "pillar dam", which can be closed if extremely high water occurs. Under normal circumstances, a considerable tidal difference will be maintained in the Oosterschelde, possibly enough to keep the cleansing plots near Yerseke in use, and supposedly enough to continue the farming of both oysters and mussels on the plots in the Oosterschelde. Progress was made in oecophysiological research on the influence on mussels exposed to air. When this happens the ATP content of the mussel tissue decreases as the result of the switch to anaerobic metabolism. Mortality under these circumstances is the result of a net energy deficiency. It was demonstrated that with rising temperatures (up to 20 degrees C.) the ATP content decreased and mortality increased. After an exposure of 4 days at 20 degrees C. the ATP content of the mussels was less than 40% of the initial value. - 10 -

Norway (K. R. Gundersen - B. Bohle) Molluscs No work on molluscs was carried out on the west coast of Norway during 1976. Mytilus edulis The laboratory study of lead uptake at different temperatures and concentrations was continued in 1976.

Poland (Not Reporting) POI~tuga 1 • (Not Reporting)

Spain (H. H. Quiroga)

Molluscs Ostrea edulis The evolution of the oyster disease caused by Marteilia refringens has been studied in imported oysters. Crassostrea angulata Periodical observations on oysters for the study of the evolution of the gill disease were made. Venerupis decussata This species which is very important from the commercial point of view is being studied. The studies done in previous years have been increased during 1976. Topics of study were: distribution, population assessment, growth. recruitment, mortality and the necessary parameters on which to base the analytical model for the regulation of this fishery. - 11 -

Cerastoderma edule Some natural beds of cockles have been studied during the past year. Studies were done to investigate growth, size of capture, recruitment, and mortality. The most important natural beds are located in Galicia (NW of Spain) and are heavily fished in autumn. Octopus vulgaris The population dynamics of this species for the Atlantic and the Mediterranean coast were studied. The work included: a) Distribution, abundance and habitat; b) Population structure; c) Growth and gonad development; d) Reproduction; e) Migration, and f) Application of the different models of population dynamies. Mussels Studies on the growth and epifauna of mussels growing on rafts in the Ria de Arosa were continued in the same way as in 1975. Sample stations were increased to compare communities composition in different zones. Other bivalves Two species, Cytherea chione and Cardium tuberculatum were studied on the Mediterranean coast. The study included: fishing area, fleet, effort, biology, growth, mortality, recruitment and population dynamies, statistics and fishing gear. Benthos Gelidium sesguipedale Studies of the red seaweed natural beds were continued in the same way as in previous years. Echinodermata The distribution, biomass and dynamics of starfishes, echnoids and holothurians in the Ria de Arosa were studied. • Polycheta Studies were conducted on the populations of hard strata in the NE of Spain. Communities in soft strata were studied in a confined area and related to the total ecosystem. Benthic communities of the Bilbao area (N. of Spain) have been typified and mapped. - 12 -

Sweden (H. Ha11bäck)

Mo11uscs In 1976 cu1ture experiments were started on the northern part of the Swedish west-coast. Species used were Myti1us edu1is, Ostrea edu1is and Crassostrea gigas (from England). About 10 private cu1ture ventures on Mytilus edulis were started in 1975-76. Benthos The diving studies on the effects of warm water discharge from nuc1ear power stations on macrobenthos were continued.

Uni ted Kingdom (J. Mason - P. R. Walne) Mo11uscs Pecten maximus and Chlamys opercu1aris Monitoring of changes in the stock composition, catch and effort in the principa1 sca110p (f. Maximus) fisheries was maintained. An analysis of resu1ts from the south-west Scottish fisheries was continued, conc1usions being drawn regarding possib1e changes in fishing po1icy. The queen (I. opercu1aris) fisheries were simi1ar1y monitored. Studies on the settlement and early life history of both species were continued. Studies on dredge efficiency and selectivity were continued in Scot1and with special reference to the angle of attack of the teeth. General fisheries monitoring has been undertaken at all the main ports along the Eng1ish Channel. This includes the co11ection of catch data and the size and age c1asses of the population. Observations were also made on seasona1 gonad deve10pment. • Fishing in 1976 in England and Wales was almost entire1y on stocks of the giant sca1lop (Pecten maximus), the 1andings of which rose to reach a first sa1e va1ue of ~2 million and research effort on this species has been increased. Back measurement of she11s has indicated that considerable differences exist in the growth pattern of sca110ps from the various Eng1ish fisheries, stocks in the south-west of England being especial1y slow-growing. Regional differences were also apparent in the seasonal variation in meat yieldjgonad condition. - 13 - The data collected indicated that, whereas a sharp sudden spawning occurred in eastern English Channel beds in mid-summer, spawning was more gradual in stocks further west (ie off Cornwall). Additional information on pectinid settlement and growth was obtained from experiments using tray-1ike artificia1 co11ectors which served a dual purpose of providing settlement surfaces and acting as growing-on cages. A number of these were 1aid near Brixham, in south-west England, in May 1976. Settlement seemed continuous in these unti1 December, so that considerab1e overcrowding took p1ace, resu1ting in approx 75% morta1ity. Despite this, numbers in December were approximately 3-4,000 Chlamys per co11ector (mean size 21 mm) and 50 Pecten per co11ector (mean size 26 mm). Cerastoderma edule A study of the effect of proposed intertida1 freshwater reservoirs on cock1e fisheries in the Wash was comp1eted. In the Wash, work has continued to locate beds of predominant1y undersized cockles which wou1d merit protection by closure to avoid morta1ities due to disturbance whi1st fishing. A survey of the Burry In1et (South Wales) cock1e fishery, which has recent1y been in dec1ine due main1y to adverse topographica1 changes, indicated that the 1976 spatfall was poor and recovery of this fishery will • not take p1ace in the near future. Lo1igo forbesi Landings and catch composition were studied together with the bio10gy and distribution. Ostrea edulis The major production of this species in England in 1976 was from the Solent fishery. A large proportion of the stock taken from the Solent was exported for relaying purposes in France, Holland and Spain to aid those regions which werp short of supplies following disease. Surveys of this important fishery were undertaken and it has been found that a severe problem of an increase in numbers of the European rough tingle (Ocenebra erinacea) has developed in the Solent. Some progress has been made with new techniques for growing small seed oysters produced from hatcheries and a number of potential nursery sites have been identified.

> • Crassostrea gigas Areas where the growth of this species in England and Wales has been poor have been identified and laboratory experiments indicate that high levels of silt in the water prevent adequate feeding by this species. Further work will be carried out to verify these findings. Production of this species in areas where growth is good shou1d increase rapidly in the next few years. - 14 - Biva1ve culture and oyster fisheries in Scotland Interest in cultivating oysters, musse1s and pectinids commercia11y continues to grow. Growth, fattening and morta1ity were studied. Seasona1 changes in the f1esh condition in relation to gonad changes were studied in Crassostrea gigas. Fo11owing the recent revival of the commercia1 fishery for Ostrea edulis in Loch Ryan, a survey of the stocks was undertaken joint1y with the MAFF laboratory, Burnham-on-Crouch. Surveys showed no major changes in the distribution of pests and diseases of mo11uscs. Samp1es of mo11uscs for export and import were examined to ensure freedom from pests and diseases. Bivalve cu1tivation in England and Wales Larvae The efficiency of production of oyster spat in 1arge-sca1e larval rearing has progressive1y improved since 1973. In 1976 efficiency in terms of f. gigas spat obtained per 1 of sea water medium used throughout larval rearing was 77.6 compared with 43.3 in 1973. The values for O. edu1is were • 82.7 in 1974 and 119.9 in 1976. Improvements are largely attributed to the greater experience of staff and greater reliability in alga1 production. The percentage of fertilized f. gigas eggs which develop to viable D-larvae in 24 h has been shown to be sensitive to variations in the quality of natural sea water. During the year a bioassay technique based on the proportion of fertilized eggs which developed into normal D-larvae was established. The assay utilises 30 ml samp1es, takes 24 hours, and the standard medium is a synthetic sea water. The gross biochemical composition of Tetraselmis, Isochrysis and Chaetoceros has been altered by varying the amount of nitrate in the growth medium. Each species could be produced either with a high proportion of protein together with low carbohydrate in high nitrate medium, or the reverse in low nitrate medium. These differences in proportional composition did not have a significant effect on the growth of Crassostrea gigas 1arvae. Spatfall was, however, significantly greater (p < 0.05) on a high protein • Tetraselmis diet, although subsequent spat growth was reduced. In terms of food va1ue to larvae Chaetoceros was superior to Tetraselmis which, in turn, was better than Isochrysis. Differences in terms of gross biochemical composition between them do not explain differences in their relative food value. - 15 -

Juveniles The experiments have concentrated on methods of handling hatchery reared spat until they are large enough to lay on the sea bed. Trays and tubes (1 m x 10 cm) made withl mm mesh allow 10 mg spat to grow to 100 mg in 6-8 weeks in the Menai Straits, with less than 20% mortality. The tubes can hold 2,000 spat and trays up to 12 spat/cm2 • At 100 mg the spat can be moved to a 6 mm mesh until they reach 1 9 in weight. At this size oysters can be laid directly on the ground provided they are surrounded with a crab­ proof fence. The shore crab is abundant on our oyster ground. Monthly population estimates, using mark-recapture methods, confirmed in 1975 seasonal pattern of abundance with fewest crabs onshore in January-February and peak numbers from May to August, apart from a temporary reduction in June due to moult and mating. During the peak months, average densities on"the shore were 1-2 crabs/m2 during high-water compared to 1-3/m2 in 1975. Underwater television observations over a further six daylight tides showed from 57 to 130 crabs per metre width of shore moving upshore during neap and small spring tides from May to August 1976 (cf. 60-120/m for three tides in 1975). Shellfish nests Checks have continued to be made on the distribution of the drill Urosalpinx cinerea and the recently introduced seaweed Sargassum muticum. The former is still confined to SE England, but Sargassum was found to have settled in areas to the west of the main populations round the Isle of Wight. The small numbers of attached plants found were all removed in areas such as the River Yealm and Plymouth but the abundance of this weed on the Solent beds continues to increase despite hand gathering attempts at eradication. Benthos Base line surveys were made of the benthos fish food affected by the development of oil related industries (Shetland, Orkney, Sound of Raasay) and the dumping at sea of industrial wastes and sewage sludge (Firth of Clyde, Firth of Forth). The effects of pollutants such as oil, sewage etc on benthic communities and a commercially exploited invertebrate species (Crangon) were • tested experimentally in tanks or in large underwaterchambers. The long term study of the evolution of subtidal benthic populations on a sandy ground in Loch Ewe was continued by means of further surveys and the compilation of data obtained over a 10 year period. .. 16 ..

U. S. A. (J. E. Hanks - J. B. Pearce - M. A. Trafford)

Moll uscs Molluscan Shellfish Research The research at Milford Laboratory, North-east Fisheries Center~ NMFS, during 1976 emphasized studies of nutrition, disease and breeding genetics with the American oyster, ~. virginica, and rearing methodology with the bay scallop, Argopecten irradians, and the surf clam, Spisula solidissima. Nutrition In commercial hatcheries the frequent subculture and maintenance of starter cultures of pure algal strains presents a formidable obstacle ~ and expense. We are working on methods that should solve this difficulty. A unique method described for the first time was developed that allows algae to grow on various types of paper substrates. The method is simple, inexpensive and permits long-term viability of the strains;. strains could survive in the cold for as long as 4-12 months. Growth of 39 strains on various paper substrates was described in a manuscript by Ukeles and Bishop, published in the Journal of Phycology, entitled, "An Unusual Method for Culture of Unicellular Marine Algae". Experiments are now in progress to investigate another method for long-term preservation of algal cells, i.e., cryopreservation. Our preliminary results show that of 6 species tested, 4 remain viable after liquid nitrogen freezing in appropriate cryoprotectants. Inorganic and organic pollutants in seawater brought into hatcheries for the cultivation of algal food cells can influence the results of the food harvest and hatchery productivity. A study on the effects of simple organic compounds was completed and reported in a manuscript by Ukeles and Rose, published in Marine.Biology, entitled, "Observations on Organic Carbon Utilization by Photosynthetic Marine Algae". Organic carbon utilization of 15 sugars, 19 acids, and 16 alcohols was studied in 13 species of unicellular marine algae. ~ A study of the effect of the inorganic pollutants, selenium and lithium, is in progress. Work in progress is attempting to develop critical systems for cultivation of oyster veliger larvae in the absence of other organisms and in a defined medium to understand the precise nutritional requirements of the animal. We have spent considerable time on this project but complete success has not been achieved as yet. An excellent antibiotic mixture that is effective in removing bacteria without affecting larvae was developed and other information is being gathered.on numerous subtle factors that influence the feeding process - 17 -

in oyster larvae. The paper presented by Dr. R. Ukeles. "Views on Bivalve Larvae Nutrition" at the First International Conference on Aquaculture was published in the Proceedings of the Conference. Available information on the cultivation of marine unicellular algae was reviewed in an invited paper. "Cultivation, Unicellular Plants", published in the Treatise on Marine Ecology, Vol. 111, ed. by O. Kinne. The following is abrief outline of the material covered: 1) Introduction a) purpose and scope of cultivation, b) availability of species; 2) Laboratory culture, a) technological and procedural aspects, b) chemical aspects - illumination, temperature. cultures, c) pond and embayment cultures; 3) Harvesting, a) methods, b) yield determination. Disease The areas of research comprlslng this investigation include assistance to commercial hatcheries and research programs experiencing shellfish disease problems, identification of bacterial pathogens, disease control, and inactivation of toxins. The data comparing conventional methods for characterizing marine • bacteria with the more rapid A.P.I. and r~initex systems are being studied to determine whether parts of the latter two systems can be used routinely in con­ junction with the conventional methods. Attempts are being made to determine the deoxyribonucleic acid base composition of known bacterial pathogens in order to speciate these microorganisms. Ultraviolet irradiation of a red pseudomonad which is pathogenic to oyster and clam larvae can result in the formation of mutants; some of these mutants are as pathogenic as the parental strain, if not more so, if the exposure to UV light is not adequate to kill this microorganism. Studies, however, have shown that an Aquafine ultraviolet sterilizer is sufficient to kill this pathogen when present at a concentration of 10 5 cells/ml of 10~ filtered seawater. Other known bacteria1 pathogens also will be tested so that the effectiveness of this sterilizer in controlling diseases can be ascertained. Exposure for 10 minutes to a 110 ml/min ozone treatment is sufficient to inactivate a 10 5 MLD dose of purified Clostridium botulinum type E toxin. Plans are under way to try to inactivate oth~r C. botulinum toxins. Genetics Selection, inbreeding and hybridization experiments on the American oyster, Crassostrea virginica, have once again been initiated. Several generations of continuous experimental breeding will provide the information commercial breeders need to make decisions regarding their own hatchery breeding programs. - 18 -

The mass selection project was begun in the winter of 1976. During the ensuing months over 20,000 oyster spat were reared and will form the first selected generation of the experiment. Three separate selection lines are to be maintained - a high selected line, a low selected line and a control line. These lines will advise commercial breeders on expected selection progress- • over a number of generations and will serve, at the same time, as a demonstra- tion. It is anticipated that only one selection generation can be achieved every two years. In alternating years as the present, then, one-generation crosses will be set up to provide theoretical estimates of heritability and, also, information on the suitability offimily as opposed to mass selection for commercial traits in the oyster. Oyster lines being established for the purpose of estimating any dele­ terious effects of inbreeding are to be crossed systematically. These crosses will be appraised for hybrid vigor. The desirability of commercial programs of inbreeding lines to be crossed for obtaining superior hybrids will so be appraised. A technique for inducing parthenogenic development of molluscan eggs now being worked out will be applied on large-culture scale in efforts to obtain in one generation the genetic equivalent of shellfish inbred several generations by traditional crossing. • Closely related oyster species are to be utilized in studies of inter­ species hybridization. Emphasis is to be on the backcrossing of the F, hybrids to local commercial oysters. Temporary, reversible chemical inhibition of fertilization of shellfish eggs spawned in mass is being researched. Such inhibition should enable mass spawning even of stock intended as use for the female parent in large-scale commercial production of oyster and other shell­ fish hybrids. Rearing The bay scallop is a highly-prized species with an excellent market demand that is seldom satisfied by the wild harvest. Its rapid growth rate and early maturity make it a likely candidate for hatchery culture. The surf clam has been well received by the general public in recent years. Con­ sidering its hardiness and rapid growth in hatchery environments, its potential as an aquaculture species generating new products from rapidly-grown, small-sized individuals is worthy of investigation. With the use of standard ripening methods consisting of elevated temperature (mid-20's degrees C.) and heavy feeding, we ripened scallops as • early as February. Using this technique, ripe animals were available from February to mid-fall. During October and November, ripe scallops were obtained by re-ripening animals that had spawned in mid-summer. Spawning was accomplished by manipulating the water temperature. Best production of gametes was obtained when the scallops were not disturbed during the act of spawning. Standing water cultures changed daily gave better survival and growth of most stages of scallop larvae than did flow-thru systems. Antibiotics were not used prophylactically in larval cultures but, when needed, Neomycin was the compound of choice. Growth of the larvae was slightly retarded at effective concentrations, but survival was dramatically improved. - 19 - In contrast to ear1y and intermediate stage 1arvae which did best in standing cu1ture. mature 1arvae and the subsequent set metamorphosed and grew best in f1ow-thru systems where food is added constant1y and metabo1ic wastes are carried away. In this environment. we routine1y set and grew about 50% of 1arvae averaging 190 microns to 700 microns in 7 days. Juvenile sca110ps grew best in the 1aboratory/hatchery in unfiltered. warmed. f10wing harbor water. Surviva1 and growth in this environment exceeded that in any combination of filtered/flow-thru/recirculated seawater. plus cul­ tured algae. No growth occurred at temperatures up to 11 degrees C; between 12 degrees C and 16 degrees C there was some growth, especial1y in the upper part of the range; at temperatures of 17 degrees C to 26 degrees C, sca110ps tripled their length in 12 weeks (11 mm to 35 mm). Standard conditioning techniques (warmed seawater and supp1ementa1 feeding) produced ripe surf clams by early March. Animals conditioned at 15 degrees C were more responsive to thermal spawning stimulation than were those conditioned at 20 degrees C. Standing water cultures at room temperature (20-22 degrees C) and Mi1ford Harbor salinity (26-27 ppt) routine1y gave adequate survival and growth of c1am larvae to metamorphosis when antibiotics were used prophy1actical1y. In this environment. about 15% of the larvae reach metamorphosis rapidly and • in excellent condition. This percentage may be improved by further studies of the temperature-salinity relationship which are planned for the future. As the larvae approached metamorphosis. significantly better setting and post-set survival were obtained if the young clams were grown in flowing seawater with cu1tured algae added constantly. Post-set clams reared in filtered. flowing seawater to which cu1tured algae are added grow rapidly. doubling their biomass and tripling their length in 10 days. The rate of growth in this system appeared to be inversely related to stocking density. Larger clams were grown in the laboratory in unfiltered seawater. Here. clams about 0.3 mm long recorded growth ranging from 2 to 10 mm in three weeks. State-Federa1 Shellfish and ßenthiC Research During calendar year 1976. twenty projects involving some phase of mol1uscan research were conducted by seven states in the Northeast Region at an estimated total cost of $515.162. A summary. by state. of the type of research, project duration and level of funding is appended and highlights of selected • studies invo1ving the soft c1am, Mya arenaria. and the b1ue musse1, Myti1us edu1is, are described below. Initiation of Statewide Intensive C1am Management in Maine Many of the important marine species are experiencing heavy fishing pressure and fishery stocks are a1ready dep1eted or being depleted at an acc­ elerated rate. Soft c1ams. one of the most va1uab1e species. are being great1y - 20 - overexploited. Commercial diggers and town officials have expressed concern about the extreme competition for the clam stocks and have requested assistance for the clam management to reduce fishing pressure. The problems in the clam fishery are immediately pressing because of: 1) The low level of stocks projected for the next 8-10 years caused by over-harvesting and proliferation of the principal clam predator, the green crab, Carcinides maenas; 2) The recent Supreme Court ruling that certain town management privileges, particularly those related to non-resident user limitations, must be supported by good conservation,facts; and 3) The impact of biotoxins and bacterial pollution on the availability of supply. During 1976, meetings were held with the Clam Conservation Committee of towns in Maine whose ordinances required reviewing. Those towns which did not have municipal licensing systems were encouraged to establish one. The towns were also encouraged to provide stronger participation in the collection of clam resource da ta and to initiate partial management measures. Biologists from the Maine Department of Marine Resources conducted training sessions on clam population samp1ing methods with survey teams comprised of town, university and consu1ting firm personnel. The program consisted of lectures covering the techniques - grid layout, sampling instances, and size frequency and growth data interpretation. Initially, the problem of coordinating the work of • several organizations involved in clam management loomed large. As the organizations were identified, meetings were held to exp1ain the program and to arrange for training to meet performance standards. A memorandum of agreement was eventually developed. In another job conducted under this study, three experimental areas were established for the purpose of demonstrating management concepts and perfor­ ming relevant experiments. The emphasis of the experimental demonstration areas was concerned with assessing the impact of green crab predation on the clam resource. Two methods are being used for this purpose: 1) The crab fence designed and tested during the last high pulse of green crab predation in the 1950·s, and 2) ~II mesh 60· x 11 I plastic netting blanketed over the clam flats. Recent sampling indicated that predation is increasing in some areas, whi1e the range of the area impacted has not changed since November 1975. It is anticipated when the towns and industry more fully realize the adverse economic impact due to the low levels of clam abundance, the acceptance of more complete management will be more easily obtained. Maine Marine Resources Fisheries Extension There has been an increasing trend for the states in the Northeast • to develop and encourage utilization by industry of the Region's so-called underutilized marine species. Of these, the blue mussel fishery has been recently attracting attention. This fishery, in spite of some adverse red tide publicity, increased significantly in Maine during the spring and summer of 1976. The University of Maine, University of New Hampshire, Maine Department of Marine Resources and private industry are working together cooperatively on a project to provide information concerning the harvesting methods, processing techniques and avail­ ability of the blue mussel resource. A direct result of this project has been ...------

- 21 -

a tenfo1d increase in the 1andings of musse1s in Maine since 1972. There are present1y about 40 dealers handling musse1s throughout Maine, whi1e on1y three years aga there were just two. Most of the musse1s are harvested by the old "pitchforks and dory" methode In an attempt to increase harvesting efficiency, project personne1 tested a Mary1and esca1ator dredge and washer as a mussel harvesting mechanism. A1though the dredge worked quite we11, the bottom configuration and rocks made operation of this gear most difficu1t. It was determined that whi1e the gear is successful in Chesapeake Bay, it is not practical for use in Maine without further modification. Mary1and Seafood Marketing A Maryland seafood marketing project has undertaken a new study in 1976 regarding the marketing of Maryland blue mussels. Currently, mussels are available throughout Chesapeake Bay, but are not being harvested commercially. The Maryland Department of Natural Resources has surveyed approximate1y 100 restaurants in the Ba1timore-Washington area and located a potential in at least 20% of those contacted. These restaurants are present1y purchasing . their products from Maine, Massachusetts and Rhode Is1and. Upon conducting a quality evaluation test of Mary1and b1ue musse1s versus the New England • variety, Mary1and ' s were found to be smaller than those of New England, but the flavor was the same. Studies such as these are continuing to assume an integral ro1e in deve1oping, managing, and realizing the fu11 potential of the nation's aquatic resources. Benthos Numerous benthic studies have been conducted in the northwest At1antic Ocean off the coast1ine of U.S.A. during 1976. This geographic area is of particu1ar significance to ICES because of extensive populations of demersa1 fish dependent on benthiC organisms for food, ICNAF fisheries agreements in the area, and because of the dense populations and heavy industria1ization which may affect the qua1ity of coastal waters in the ICNAF areas. Extensive benthic studies have continued in the New York Bight apex. Personnel assigned to the Sandy Hook Laboratory, Northeast Fisheries Center, NMFS, have developed detai1ed data reports concerned with quarter1y samp1ing at severa1 hundred benthic stations located in the Middle Atlantic Bight; their locations extend from the heavi1y pol1uted New York Bight apex across the continental she1f to waters over 3,000 meters • in depth. The data reports and associated pub1ished papers contain information on the distribution and abundance of benthic organisms and associated chemical/ geo1ogica1 parameters, such as heavy metal levels, hydrocarbon va1ues and sed­ iment type. Seabed respiration studies have been conducted at many of these stations using the Pamatmat multiple corer and methodo1ogies. In addition to research on benthic communities of the New York and Midd1e At1antic Bights, scientists attached to Sandy Hook Laboratory have continued to investigate benthic populations in heavi1y used and po11uted coastal embayments, such as Raritan Bay and Long Is1and Sound. These scientists have also continued to study the impact of estuarine dredging and spoiling in coastal water. Aseries of data reports and published papers important in management decisions have been developed in connection with these research activities. An extensive fish kill occurred off the coast of New Jersey in the summer of 1976. Large mortalities of benthic organisms were ------

- 22 - observed and measured. These include the valuable surf clam, Spisula solidissima. The kill was a result of anoxia, or oxygen depletion, which covered an area of. 25,000 km 2 extending from Long Island Sound to beyond Delaware Bay and seaward for 100 km. Present benthic studies and related data bases are being incorporated into a long-term research and monitoring program designed to permit evaluation of long-range changes due to natural environmental variation and the impact of manls activities on coastal environments. Scientists of the University of Delaware, College of Marine Studies, have collected 1,303 quantitative grab and 887 qualitative dredge samples from ten different sites in the Delaware Bay complex, including Delaware Bay, per se, two small bays (Indian River and Rehoboth Bay) , coastal waters, and the midcontinental shelf off Delaware Bay. Dominant species of Delaware Bay were similar to those in coastal bays of New Jersey on the north and Chesapeake Bay on the south. However, the number of species and density of invertebrates in Delaware Bay were very low compared to surrounding waters and other uncontaminated estuaries arid bays throughout the Mid-Atlantic Bight and the world. The reasons for observed low secondary benthic production may be related to pollution, lack of attached macroalgae, sediment transport and • hydrography, and predation. The fauna of Delaware's coastal zoneand the fauna on the mid­ continental shelf off the Delmarva Peninsula are characteristic of the sand fauna which ranges from Nantucket to Cape Hatteras. Work in the Delaware Bay region has been described in a number of papers or papers in press. The Virginia Institute of Marine Science (VIMS) is conducting extensive studies on the benthos of the continental shelf and upper slope in the Middle Atlantic Bight. Macrobenthos is sampled by bottom grab at stations ranging from off northern New Jersey to Virginia, quarterly or semi-annually. Megabenthos and macrobenthos are sampled quarterly in a central study area proposed for petroleum exploration and development off southern New Jersey and Delaware. Stratified random sampling of megabenthos and macrobenthos in two topographically complex outer shelf areas containing oil and gas lease tracts was conducted in conjunction with sampling of d~~ersal fishes. VIMS scientists are relating the distribution of benthos to • hydrographic conditions, sedimentary parameters and the distribution of trace metals and hydrocarbons. Benthic communities are being related to the food habits of bottom feeding fishes now being studied by investigators in the Ichthyology Department. Recolonization field experiments are being conducted at one site to determine the role of disturbance in macrobenthic community structure and to assess the recovery rates of the community following perturbation and incorporation of oil in sediments. - 23 - Few areas have been sampled over long enough periods to determine the long-term persistence of benthic communities. VIMS is continuing monitoring of several sites producing data sets on some Chesapeake Bay communities going back 17 years. Several communitiesstudied intensively in the 1960's are being resampled periodically to produce long-term data bases with which to judge the effects of environmental or climatological changes. Benthic research ongoing at the Ira C. Darling Center (ICDC). University of Maine. emphasizes the systematics and ecology of peracarid crustaceans from the continental shelf and upper slope in the region. New Jersey to Virginia. as well as of amphipods from Georges Bank off New England. The distribution of cumaceans along the northeastern coast of the Uni ted States is also under investigation. ICDC personnel are also developing methods of estimating the structure of benthic assemblages using dredge samples and relative abundance indices. Studies of the benthic assemblages of two main estuaries and an investigation into the causes of patchy distribution in muddy sediments are in the planning stages. Benthos research at the Northeast Fisheries Center, Woods Hole, Massachusetts, was centered around two major investigations. One investigation pertained to the study of th~ quantitative composition of the standing crop of macrobenthic invertebrate animals inhabiting the Gulf of Maine-Georges Bank region. Another investigation dealt with the methodology and sampling gear • comparisons resulting from a study of the megafauna in the Veatch Canyon area southwest of Georges Bank. Last fall a two-part report describing the macrobenthic invertebrate fauna inhabiting the Middle Atlantic Bight region was submitted to the Marine Ecosystems Analysis Program. New York Bight Project. Part 1 of the report. '34 pages. consisted of collection data and environmental measurements; Part 11, 395 pages, dealt with the faunal composition and the quantitative distribution. Emphasis was placed on geographical distribution, and relationships with water depth. temperature range of bottom water, and bottom sediment types.

A general itemized statement showing the extent of State-Federal work follows: • - 24 -

Ealendar Year 1976 Project ':'itle Grantee Duration Scope Total Proiect Cost I State N:-'J"S of Marine Resources 1/7/74-3/31/77 Document community structure, temporal 33,138 ~~""O, SCU'Y 0' eh, Sh"P~' $ $ 4,069 $ 4,069 ['OC Riv., ..".,y .!! SC." of Maine changes and distribution, faunal sta- bility, and to establish a base Hne I, study against which to measure effects of environmental alterations. I .h~ 1ni t~a tion of State_ Dept. of Marine Resources 9/1/75-8/31/78 Establish Clam (.!.~ arenarial Manage- 109,700 13,348 13,348 f-lice 1r.':ensive C1am State of Maine ment Cnit Areas with towns as primary ·~J..:li! ~(: ~e n t manaaement aaent under State auidelines2/ '::lrine Reso:lrces Fisheries Dept. of Marine Resources 1/1/76-12/31/78 Assist in development of cornmercial 119,000 17,500 17,500 ~xter.sicn y State of Haine fisheries. Conduct resource inventories and gear development projects with re- gard to harvesting the mahogany qua~og. Promote harvesting of "underutilized" fisheries including the blue mussel.2j I ~cal1op Population Dynamics Dept. of Marine Resources 9/1/76-5/31/i9 Develop rcliable method of tagging 70,000 3,630 3,630 State of Maine scallops. Determine if present tech- niques of aging scallops are valid. De- termine if there are differences in growth among different calendar years and among scallops of different ages and different growing area!l. ro11ection, COI:l;::> i 1ation, Division of Mar~ne Fisher- 7/1/73-6/30/78 Summarize annual reports of landings 203,300 9,419 28,258 'Nah:ation & Dissemination ies - State of Massachusetts from she11fishermen, and dealer trans- pf Co~mercial Fisheries actions to ensure ful1 coverage of . tatistics 11 fishery 1andings. jhe Ilfish 'recr.nical AsSl.S- Division of Marine Fisher- 1/10/73-12/31/7 Provide technica1 assistance to Shellfish 94,000 6,092 18,276 a:1ce ies - State of Massachusetts officers, town officia1s, and the Shell- fish industry regarding management, regu- lations, culture and harvesting of she11- fish reSO:lrces (soft-c1ams, bay s ca110p , oyster, quahog, blue mussel) a:1d to en- courage regional cooperation a,d parti- cipation in o1a~ni:1q resource use. I ",,::,ssilchcsetts Co:':"'.:nercia: Division of Xilrine Fisher- 1/7/74-12/31/77 Conduct "grass roots" extension progra~ 205,000 r-::S,085 45,253 isherics Extension ies - State of Massachusetts designed to service Massachusetts Com- ervicc y mercial Fishing Industry. Includes effort to deve10p ocea, q:lahog (Arctica islandica) fisherv.

•• • - 25 -

FUNDING a1endar Year 1976 ~roject Tit1e Grantee Duration Score Total Pro;ect Cost State ~~FS C~era:ion ~Qbi1e I of Labora- °Dept. of Environmenta1 Con- 4/1/76-3/31/79 Conduct sanitary surveys of She11- $114,500 $10,725 I $10,725 ~ories Car She11fish Sani- servation - State of New fish (Mercenaria ~ercenaria) har- I. 1 \ ItatJ.on Contra York vest areas and survei11ance of ! She llfish processing plants. I Shellfish Transplant in Cept. of Environmental Con- 4/1/76-3/31/79 Transplant Shellfish (:~ercenaria) 204,000 29,062 , 29,062 ~he Marine District of servation - State of New from polluted water areas to certi- I / ":c'" Yerk State II York fied (clean) areas for cleaning I and avai1abi1ity for markct harvest- ing. I . nvestigation of the Hard Dept. of Environmental Con- 7/15/76-3/31/79 Conduct hard clam ( ~ercenaria) bio- 227,200 13,838 13,83€ 1am Re::;ource of Great servation - State of New mass survey and determine extent routh Bay, ::ew York vork and impact of recreationa1 she11- fishing on the resource. . ffeet5 of :~sx Dic:ea5e on Rutgers, the State Univer- 7/1/76-6/30/79 Provide information on preva1ance 96,000 4,000 12,000 ~yster Prcduction in sity - State of New Jersey and intensity of MSX-disease in Pe1a~,are Bay oyster populations and cetermine under1ying causes of f1uctuations I in abundance of MSX and of mor- I talities resultinq from MSX disease. r:E:se~rch and Inventcry of Division of Fish, Game and 10/18/76-10/14/79 Conduct inventory of she11fish 109,554 4,565 4,565 fhellfish wi~~in Estuarine She11fisheries - State of (Mercenaria and Crassostrea) to de- bystc~~ of the At1antic l:ew Jersey termine size of the resource as an ,.oast of r:elJ .Je rsey aid to management and investigate areas for which 1eased ground ap- plications have been received. ~chnica1 Assistance to Dopt. of ~atu::al Resources 5/1/74-4/30/77 Estilblish cooperative relationship 88,000 8,333 24,998 rorr..:~ercia1 Fisheries .Y State of De1aware with resource producers, processors ilnd consumers. Supervise oyster I cu1tch planting and transplant shell- fish (;v.crcenaria) frcm po11uted to nonpolluted qrouncs. ishenes Extension Ser- ::lept. of :~a'tu:"al Resources 9/1/76-8/31/79 Faci1üate co~~unication between bio- 175,757 ":,5~8 13,552 lice y State of Märy1a.'1d 10gical-technica1-manageria1-facu1ty 1 I and the producers and processors of I fishery produets. P:,o~ote use of I under-untilizcd species of seafood, including rangia cla.~ (Ranaia cuneata) I and endorse concept of cla~ (Mercenaria) I re-population. I - 26 -

FUNDlW"J Ca1endar Year 1976 I Proieet Tit1e Grantee Duration Seooe Total Proieet Cost State NI'.FS 6eafood ~larketing y Dept. of Natural Resourees 9/1/76-6/30/79 A11eviate supply and demand imbal- $150,000 $ 8,250 $ 8,250 State of Mary1and anees and encourage uti1ization of seafood products. Promote marketing of b1ue musseis and oysters. 11 hell Planting for Oyster Marine Resourees Commission 4/1/76-3/14/79 Inerease avai1able amount of oyster 300,000 37,500 37,500 "U1tch State of Virginia cultch, determine rate of suecess in she11 p1antings and increase oyster population in areas capab1e of rearina oysters to maturity. Geafood I'~rketing y Marine Resources Commission 7/1/76-6/30/78 Educate institutional volume feeders 80,000 5,000 .l.:>,liliU State of Virginia in uses and nutritional benefits of seafood. Distribute recipes for oysterp and c1ams. .he Present and Potential Marine Resourees commission 9/15/76-6/30/80 Indicate location and acreage of 361,937 10,202 10,202 Productivity cf Bay10r State of Virginia. bottom now producing seed or market urounds in Virginia - Phase oysters, and provide guidelines to The Rappahannock River budget present and future rep1etion activities. TOTf,L_. $2,741,086 $205,136 $310, 026 1

Y Projeet ebjectives ine1ude studies in addition to these eeneerned with rnollusean research; in most eases, scope emphasizes work done with mo11uscs. y Described in text.

• ,------

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U.S.S.R . • (P. A. Moiseev)

Molluscs During 1976 the pelagic squid of the tropical Atlantic, the squid and octopus of the west African shelf, deepwater and bathypelagic shrimp were studied. The following material was collected and analysed: 2100 specimens of pelagic squid (3 species) and 2200 specimens of the shelf squid and octopus (5 species) were subjected to biological analysis. A total of 580 oceanic and 820 shelf cephalopods were subjected to helmintological analysis. The stomach contents of 450 ocean squid and 380 shelf squid and octopus were examined. Biological analysis of 1150 deepwater and bathypelagic shrimp (32 species) was made. The fecundity of 2000 shrimp of 20 species was determined. About 500 stomachsfrom deepwater shrimps were collected. The data on food and parasite relations in pelagic squid of the tropical Atlantic were analysed. Stomach contents of the squid, Sthenoteuthis pteropus, and their changes of size-age, area and sex were determined. The main food supply was represented by fish and squids, the minor food - by crustacea, pelagic molluscs and Chaetognatha. The young specimens fed mainly on er stacea and other plankton invertebrates; the increment in squid size was accompanied by the increase of the fish and squid percentage in food. Fifteen helminth species (Nematodes, Cestodes, Trematodes and Acanthocephala) parasitize squid. The total incidence of infection was 96%. The squid, Sthenoteuthis pteropus, is the intermediate and reservoir host for these paras ites .

• - 28 - CRUSTACEA Belgium (P. Hovart) Crangon crangon The monthly analyses of the shrimp-stock (Crangon crangon) and of the by-catch of experimental shrimp fishing were continued in 1976. These investigations were started in April 1973. The final objective of this study is 1) to obtain a detailed picture of the evolution of the shrimp-population along the Belgian coast over an extended period and 2) to evaluate the influence of several demersal predatory fish-species on the population dynamics of the shrimp-stock. Within the framework of this study stornach analyses have been performed on Gadus morhua, Ciliata mustela, Trigla species, Liparis liparis, Agonus cataphractus and Callionymus ~, in order to evaluate the importance of post­ larval Caridea in the food of these species. Some of these investigations will be continued in 1977. Nephrops norvegicus The commercial catch of Nephrops norvegicus has been sampled from June till October. Total length, carapace length and sex were determined. Canada (J. E. Stewart) Homarus americanus Montioring of the fishery by means of catch sampling, obtaining catch/effort data, collection tags etc. was continued in a number of represent­ ative areas around the Newfoundland coast. Studies on growth in nature were ll continued with a II sp hyrion tagging project being carried out in early summer prior to the molting period and shell condition sampling in several areas in the fall when molting was finished for the year. Tagging of commercial lobsters was carried out in several areas to determine standing stock sizes and rates of exploitation etc. during the 1977 fishing season. Field activities for 1977 will be similar. Plankton sampling of larvae was continued as part of a study of larval recruitment mechanisms and more such sampling is planned for 1977. A tag-recapture study of an unfished population of lobsters around a small island enabled 1) a relatively precise measurement of natural mortality; 2) the determination of the optimum trap density per unit area of lobster bottom; 3) an estimate of fecund females which would normally be lost from the population through fishing. Work is also being carried out on various aspects of lobster courtship and mating activity, the main topic being the effect of relative size of the male and female on their ability to mate successfully. - 29 -

Northumberland Strait Project Data from the 1975 Northumberland Strait Project on shellfish are being processed. Computer printouts of raw data on the physical environment and catches in beam trawl, scallop drags, lobster traps, bottom grabs and sediment cores are being prepared for a data repository report. Aseparate report on rock crab biology is nearing completion.. Inshore and Offshore Lobster Study In S. W. Nova Scotia a lang-term sampling program was initiated for inshore lobster landings at Port Maitland and Clarks Harbour, and for offshore lobster landings from deep water stocks on Georges &Browns Banks at Shelburne, Nova Scotia. On-board samples of total catch, including jonah crabs (Cancer borealis), were taken on two commercial offshore fishing trips to the edge of the continental shelf east of Browns Bank. In 1977 a survey of lobster larvae is planned for S. W. Nova Scotia which will extend to the . edge of the continental shelf. Hormonal Studies Eighty to ninety percent of small adult male or female lobsters caught in winter or summer were induced to molt by ir.tramuscular injections of ecdysterone triacetate. In most cases two doses were'required. At the best doses mortalities before, at or after molting were very low and did not appear to be different from control Post-molt lobsters were normal in size increases and appearance. Nutrition Three protein sources (casein, soy protein and cod fish protein concentrate) were fed individually as 40 and 60% fractions (dry wt basis) of semi-purified test diets to groups of juvenile lobsters. Casein proved to be nutritionally superior to the two other protein sources. When the 40% casein diet was supplemented with various combinations of different amino acids growth was increased significantly. Thus the lobster which on the basis of diets containing whole proteins appears to require a high protein diet may actually require substantially less protein when the food includes adequate amounts of the required amino acids. Disease Work on the bacterial disease, gaffkemia was continued on a reduced scale. The disease continues to be a problem giving riseto serious epizootic~ periodically,mainly in the holding units. The encouraging results of the recent past showing that resistance could be induced are being used as a basis for developing a killed vaccine which could have wide application. - 30 - Toxicity Studies In response to an alleged lobster kill by oil, the hepatopancreas of a number of lobsters were analyzed for hydrocarbons. Contamination of lobsters by the spilled oil could not be substantiated. A number of aromatic hydrocarbons was detected both in the sample and in contro1 hepatopancreas. The presence of aromatic hydrocarbons in lobster hepatopancreas deserves further attention. Some additives to plastics were also detected in 1aboratory-reared specimens. This brings attention to another problem, deserving further studies - contaminants introduced by aquaculture techniques. Investigation of the toxicity of heavy metals and pesticides to lobster larvae and adults was continued. Exposure of gravid females to 10 ppm cadmium did not interfere with the hatchability of fertilized eggs. Adult lobsters, however, when exposed to 10 ppm cadmium for 6 weeks or to 1 ppm for 15 weeks were rather weak and sluggish, and a re1ative1y high incidence of mortality was observed. These symptoms in anima1s that survived cou1d be reversed if the anima1s were moved into uncontaminatecrunning sea water. Cancer irroratus There was renewed interest in "rock crab" Cancer irroratus fishery in Northeastern New Brunswick, but price paid to fishermen was inadequate to support a separate rock crab fishery outside the lobster season. Instead, rock crabs were taken as ~ by-catch in the falllobster fishery. A three-week crab trap comparison was comp1eted at Shippegan. Of 7 trap-types tested, a modified lobster trap (Stasko 1975, J.F.R.B. 32: 25J5-20) with a 5 cm wide entrance the full length of the trap along the top performed best for catching crabs and for keeping lobsters out. Chionoecetes opi1io An at sea and on shore sampling programme for commercial catches in­ the western Gulf of St. Lawrence was initiated. Observations were made on she11 condition and size frequencies. Backlog data collected since 1968 on catch, effort, and size frequencies are being processed. Intensive samp1ing of commercial catches in the Gulf of St. Lawrence is planned for next year. Log books will also be distributed in order to monitor the fishery. Seasonal sampling in Newfound1and of a commercial population of the spide~ crab, Chionoecetes opilio, revealed both summer and winter molting periods. Recently mol ted crabs were exposed to ambient air temperatures for 3 and 30 minutes in both summer and winter and returned to the water. Survival exceeded 70% for both winter exposures and the short summer exposure but dropped to 30% for the long summer exposure. These results support management decisions requiring fishermen to return recent1y mol ted crabs to the water on the fishing ground and c10sing fishing during the summer mo1ting season. - ~1 - Pandalus borealis Monthly sampling of the commercial shrimp fishery at Port au Choix, • Newfoundland was continued to determine catch/effort, size distribution and ratios of shrimp to small redfish. A 41 day charter vessel cruise covering the entire Gulf of St. Lawrence was conducted using a standard #36 shrimp net. The purpose of the cruise was to determine by means of a stratified-random sampling scheme the abundance of shrimp and small redfish available to the shrimp trawl in the Gulf region. Data frem this cruise was used to compute shrimp biomass estimates as well as ratios of small redfish to shrimp.

Denmark (Horne waters - S. Munch - Petersen Greenland waters - E. Smidt) Nephrops norvegicus The work carried out during 1976 in Danish waters has been a continuation of the investigations during 1975 on the activity and catchability of the Norway lobster. Some of the results were presented at the Special Meeting on Population Assessments of Shellfish Stocks (No. 57.) Carcinus maenas Investigations for the purpose of estimating the density of Carcinus maenas at various localities in Kattegat are planned for 1977. Chionoecetes opilio Trap fishing experiments for queen crab have been continued in West Greenland inshore waters. Pandalus borealis Inshore investigations were made in Disko Bay (ICNAF Div. lA), and offshore investigations were made in Divs. lB-1F, mainly in lB where most part cf the international shrimp fishery is concentrated. The results of the offshore investigations were reported, together with information from other countries, to the ICNAF Shrimp Working Group in November-December 1976 for estimating a TAC. Methods used to study the shrimp stocks: 1. Co11ecting of catch-effort data from commercial fisheries and from the research vessel. In July a commercial trawler was placed at the disposal of the fisheries research by the Royal Greenland Trade Department for a stratified survey in the northern region (Div. 1B) - 32 - 2. Sampling from commercial and research fisheries for calculation of year class strength and mortality. 3. Bottom photography to study the density of the shrimps (c.3500 pictures were taken in Disko Bay). 4. Tagging experiments (co 6000 shrimps were tagged in Disko Bay). 5. Plankton sampling to study the occurrence of shrimp larvae. Investigations in 1977 are planned mainly along the same lines as in 1976, but with more stress laid on the offshore area; no tagging experiments will be made.

Finland (Reported on Benthos Only)

France (J. Audoin) Langoustines(Nephrops norvegicus) Biologie et guestion des stocks: , L'ltude de la croissance de la langoustine a ete poursuivie grace a 1 1 observation du deroulement du cycle d'intermue sur des crustaces preleves au cours d'echantillonnages mensuels a bord des bateaux commerciaux dans le secter VIlla. Des releves des aports et efforts de peche par secteurs statistiques ont ete effectues. Travaux a la mer Deux campagnes d bord du navire oceanographique Roselys 11 en Avril et Septembre ont permis d'~valuer 1'effet immediat q'aurait sur la composition des captures de langoustines au Nord du golfe de Gascogne 1'adoption du maillage reglementaire de 60 mm. Enhantillonnage Annee 1976 (region VIlla) Nombre d' echantillons: 2 (provenant de navires de recherche) 12 (provenant de bateaux commerciaux) Nombre de langoustines mesurees: 53 435 Homards (Homarus gammarus) Les op~rations de repeuplement des zones coiti~res par 1'immersion de post-larves produites en ecloseries ont ete poursuivies. Le niveau de production a.atteint 200 000 en 1976 (Ecloseries d'Yeu et de Houat) , Des echantillonnages ont ete realises lors des prospections faites a - 33 -

bord de bateaux de p~ches dans le secteur de 1'Ile d'Yeu (N=304) et de Noirmoutier-Le Croisic (N=250) . • Le contrale des apports a ete effectue dans divers secteurs, principalement a 1'Ile d'Yeu, 1'Ile d'Houat, le Conquet et Roscoff (Institut • des Peches Maritimes et COB) Programme 1977 Poursuite des recherches sur la biologie du homard et les techniques de marquage des juveniles. Collecte des donnees sur les apports et 1'effort de peche. Arignee de mer (Maia squinado) l'Institut des P~ches Maritimes a poursuivi 1'etude de la pgcherie d'araignees du Golfe normand-breton et plus particulierement de la zone d'hivernage situee dans le N-E des Roches-Douvres. Des marquages ont ete effectues en Janvier 1976 (N=500). les '_ resultats obtenus seront compl€te#s en 1977. Federal Republic of Germany (K. Ti ews) Crangon crangon Investigations of the Institut fur Kusten- und Binnenfischerei to assess the shares of undersized protected fish in the catch of the German shrimp fishery and the fluctuations in the abundance of fish species found on the shrimp fishing grounds were continued. A total of 330 samples (= 1 650 kg) of unsorted catch of the shrimp fishery were collected in Busum, Cuxhaven, Norddeich and analysed as to their species and length composition. The prey-predator relationship in the Crangon fishery was studied.

Pandal us ~. Samples of deep sea prawn catches made on the occasion of research cruises of FRV "S ol ea " in the Farn Deeps and on the Fladen Ground were analysed as to their species and length composition at the Institut fur Kusten- und Binnenfischerei. Iceland (Not Reporting) Ireland (C.ß. Duggan and F.A. Gibson) Investigations of Nephrops selection by different parts of the trawl were carried out in the Irish Sea (ICES Division VIla). The tagging programme on lobster (Homarus vulgaris) on the south coast (VIIa) was continued. - 34 ~

Nether1ands (P. Korringa) Crangon crangon and Penaeus brasi1iensis During 1976 an extensive study of the seasona1 migration of the brown shrimp was pub1ished. In this artic1e the migration was described on the basis of a technique to measure indirect1y the physiologica1 condition of individual shrimps. The resu1t was a new conception of pattern and aim of the seasona1 migration in the brown shrimp. The same technique was app1ied to migrating specimens of the tropical species Penaeus brasiliensis. It became clear that a great similarity exists between the pattern of migration and other bio1ogica1 aspects in Crangon crangon and Penaeus brasi1iensis, in spite of great differences in climate and migrating stimulus. A comparative study of the two species was presented on the CICAR-II Conference in Caracas on 12 - 16 Ju1y. By means of the cross corre1ation technique, the relation was defined between the number of ripe eggs of Crangon crangon in apart of the Dutch coasta1 area and the recruitment of consumption shrimps. This study made c1ear that 4It the brown shrimp grous in 4 months from a ripe egg to a 1ength ofca.55 mm and that the growing speed is about the same over a large part of the year. The strong relation between number of eggs and recruitment suggests that the Dutch shrimp stock has been overfished during the last six years.

Norway (K. R. Gundersen - B. Böh1e) Homarus gammarus Lobster investigations in the field were carried out on1y with fishing experiments on tagging loca1ities north and south of Bergen in June and Ju1y. The commercia1 catches of lobster in the spring on the coast 1ine from Fedje in the north to Krossfjord in the south were investigated in a lobster pond at G1esvaer south of Bergen. Carapace 1ength, sex and numbers of berried fema1es were observed. Data on catch and effort from loca1 fishermen on the South-East Coast have been obtained every season since 1928. Areport on these data were given at the Special Meeting on "Population Assessments of She11fish Stocks". Co11ection of data inc1uding 1ength measurements is being continued. The observation of increases in 1ength during the mou1t of untagged lobsters in aquaria were continued. Hatching and rearing of lobster larvae were carried out on a small scale in the laboratory. - 35 - Cancer pa gurus Investigations of unexploited stocks of crabs in the northern part • of Norway were continued in August and September 1976; data on size. sex and conditions were collected. • Pandalus borealis In Troms in northern Norway fishing experiments on 11 stations were carried out with otter trawls one week each month in order to find the ecological relation between the prawn stock and the amount of fish. Investigations of the fishable stock of deep sea prawn in Greenland waters were carried out in July and August 1976. Data on size. sex and catch per unit of effort were collected. The growth of individual juveniles (hatched in the laboratory) were studied.

Poland (Not Reporting)

Portugal (Not Reporting)

Spain (H. Quiroga) Nephrops norvegicus The Norway lobster populations of N. W. Spain and W. Iieland have been studied as in the previous years. Data on capture. effort, size and sex is collected monthly. Crabs The study of the crab communities, genus Micropipus. of the Ria de Arosa have been concluded. The.work was initiated, during last year, in the Ria de Muros area.

Sweden (H. Hallbäck) Homarus gammarus Lobster landings showed a small increase during 1976 compared to ------

- 36 - 1975. Catch data from some areas where only commercial fisheries take place showed that during the last 10 years catches have been the same. In most areas there is strong competition between local fishermen and "summer guests" which results in decreasing landings of lobster. New regulations are in ~ preparation for the Swedish lobster fishery. Cancer pa gurus Catch data and diving investigations show that the stock of Cancer pagurus are strong and the catches since 1972 are still increasing. Nephrops norvegicus Daily reports were obtained from about 30 trawlers including by-catches. Biolo9ical samoles were taken, when possible, every month. Catch data showed decreasing landings during 1976. Pandalus borealis Research vessel samples were measured and sex determined. Daily reports from a number shrimptrawlers were processed.

Uni ted Kingdom (J. Mason - P. R. Walne) Homarus gammarus In England and Wales collection and analysis of catch and effort statistics, together with population structure information, has continued from the main fisheries. With the completion of the development of a persistent toggle-type tag 1,778 tagged lobsters were released off Norfolk, Yorkshire and Northumberland (E. coast) to obtain information on growth, mortality and migrations for population modelling. Biological studies were carried out on catchability, recruitment, juvenile ecology, moult­ staging and behaviour to aid parameter estimation for population modelling and to enable assessment of alternative management strategies, in particular, optimum minimum landing sizes. Commercial landings of lobsters were sampled in the main Scottish fishing areas and catch and effort data were obtained from selected fishermen. Cancer pagurus and Palinurus elephas Work on both these species in England and Wales has been reduced to the monitoring of catch and effort and population structure from the major fishing areas. Collection of crab catch composition (~. pagurus) and fishing effort data was maintained in the main Scottish fishing areas. An intensive tagging and fishing programme on a lightly-fished stock of crabs in Loch Shieldaig indicated a very mobile population. - 37 -

Nephrops norvegicus • , Studies of the north-east Eng1ish coast stock have continued. In 1976 the fishery was buoyant; 1andings were the highest in recent years. Dai1y 1andings and cpue (kg per boat day) were co11ected at the major port, North Shie1ds. The c1aw tagging of 1,000 Nephrops (reported last year) has produced five returns. Migrations are approximate but appear to be 15-30 km. One individual was returned after 68 weeks without mo1ting. Commercia1 trials with a modified Gu1f of Mexico f1at trawl showed that the capture of sub-legal fish by-catch cou1d be reduced without a corresponding lass of Nephrops. The commercia1 catch of Norway lobsters was samp1ed on commercia1 vesse1s fishing the major Scottish grounds, and catch and effort data were compi1ed. Data from the Firth of Forth were assessed and a study was made of"the use of 1ength-frequency distribution for ageing Nephrops. Further comparative fishingexperiments were undertaken to compare size se1ection of Nephrops by 50 and 70 mm mesh trawls. Observations using underwater television and photographic cameras showed the c10se relationship between the trawl catch and the dawn and dusk emergence of Nephrops from their burrows. Panda1us montagui Random samp1es of shrimps have been co11ected from the Wash fishery (east coast of England) and examined for 1ength and sex frequency. Studies in the area have also indicated a relation between 1andings and annua1 mean sea temperatures. Fo11owing the very successfu1 fishery in the Wash in 1975 (annua1 1andings at the major port were 552,750 kg) it was predicted on the basis of the re1ative1y higher sea water temperatures during 1975 that 1976 1andings might dec1ine by about 30%. Final 1andings for 1976 were 238,250 kg at the major port. Panda1us borea1is The Scottish fishery on the Fladen ground underwent a 1arge increase in effort and 1andings increased corresponding1y. Samp1ing of the catch and the co11ection of catch/effort da ta were maintained. Studies of the composition and bio1ogy of the Farn Deep stocks continued. Experiments on cod-end mesh se1ectivity were conc1uded. Underwater television was used to study the behaviour of Pandalus. During 1976 stocks off the north-east coast of England attracted English fishing vessels from nearby ports. Landings for the summer months, June - September, total1ed 141 metric tonnes. This is the first time this population has been exploited by local vessels. Landings and catch-per-unit of effort data have been co11ected. - 38 ~

Crangon erangon Cateh/effort and eateh eomposition data were eolleeted from the small Solway Firth fishery.

Crustaeean eultivation • Penaeid prawns Breeding Repeated spawning of P. monodon was obtained from females from whieh one eye had been removed but all were infertile. A laboratory population of f. merguiensis repeatedly spawned viable offspring. Environment Water from a 1,250 1 eapaeity reeireulation system with a biologieal filter and stoeked with 400 f. merguiensis was regularly analysed. One third of the water was replaeed eaeh week. Amnonia, nitrite and phosphate did not exeeed levels thought to be toxie and at most were 0.4 mg NH 4-N/l, 0.7 mg N0 -N/l and 7.0 mg P0 -P/l. Levels of organie earbon however fluetuated erratieally2 between 7 and425 mg C/l. The weight of suspended matter retained on a GFC filter varied between 1.5 and 35.3 mg/l. These ehanges in clarity of recirculated water frequently oecur in our culture systems and are thought to be due to the bloom and eollapse of microbial populations. The growth and survival of densely stoeked f. merguiensis (lOO/m2) in round and square tanks were compared over a 16 week period. The prawns apparently preferred the square tanks in which they arew to a larger size. Observations showed that they sought out shelter in the corners. Nutrition In previous work pelleted diets prepared from freeze-dried Mytilus edulis meal has resulted in reasonable growth response and excellent survival of the prawn Penaeus merguiensis. A more recent experiment confirmed that heat drying (60 degrees C, 24 hours) adversely affected its potential for growth promotion. Therefore in all subsequent experimental diets onlv the freeze-dried form was ineorporated. Aseries of experiments examined the reQuirements of P. merquiensis for major nutrients. The findings have shown the need for 3% vitamin and 7% mineral mix; the addition of eod liver oil to a diet eontaining 39% protein (mussel meal) did not increase growth, and growth deelined as protein was deereased in an isocalorifie diet. In all experiments food ingestion rate tended to increase as dietary energy decreased. Excessive food consumption, poor food conversion and reduced protein effeciency was recorded at dietary energy levels below 2.8 K cal/gm. Available energy may, therefore, influence feeding rate, protein utilization and growth. Abnormally high dietary energy could reduce protein intake while low levels may lead to diversion of protein for metabolie requirements. - 39 - Lobster Juvenile growth Temperature and salinity. For the first six weeks of post-larval growth, the estimated optimum levels of these two factors are a temperature ... of 21 degrees C combined with a salinity of 30 ppt. At the optimum salinity, 95% of the maximum theoretical yield should be obtained over a temperature range of 19-22 degrees C. At the optimum temperature the respective salinity range is 27-33 ppt.

Container size. In the range of pot sizes tested (1 11 -6" diameter), both the growth rate and length increment at moult tended to increase with the size of container. Shelter. In one experiment the mean dry weight after 12 weeks, and length increase at moult, were significantly greater in lobsters which were provided with semicircular PVC shelters approximately l~ times their total length. Feeding frequency. Feeding every two days did not produce significantly less growth than daily feeding. As a result of the lower absolute amounts of food consumed at the lower fep.ding levels, food conversion is better. The weight increase over a 31 day period of lobsters fed every two days was 11% less than for those fed daily, but 34% less food was eaten.

U. S. A. (Reporting on Molluscs and Benthos Only)

U. S. S.·R. (P. A. Moiseev - A. F. Karpevich) Pandalus borealis Age-size composition, biochemical and morphometric peculiarities of deepwater prawn, Pandalus borealis;-were studied in different par~ of the Barents Sea. Data on distribution of adult individuals and larvae of this species were collected. Paralithodes camchatica

In 1965 it was reported that wor~ on acclimatization of king crab, Paralithodes camchatica in the Barents Se~ began in the USSR (Vu.I.Orlov and A.F. Karpevich - Extrait du Rapports et proces Verbaux vol.156,59-61,1965). Works on transplantation of crabs were carried out in 1960-1969. 2490 adult individuals, more than 790 big young crabs and about 10,000 young individuals were transplanted during that period. Taking into account the small amount of the transplanted material and long life cycle of crabs (over 10-12 years) one could expect results in 10-15 years. In 1974 one capture was reported and in summer 1976 seven males and females weighing 3 5-4 kg were caught in the Kola Bay. In the Barents Sea crabs were caught too. The USSR will appreciate greatly - 40 - any information on captures of king crabs in European waters, their size and weight, maturity rate and sex.