RAPPORTS ET PROCÈS-VERBAUX DES RÉUNIONS VOLUME 175 POPULATION ASSESSMENTS OF SHELLFISH STOCKS A Special Meeting held in Charlottenlund, 29 September-1 October 1976 E dited by H. J. THOMAS CONSEIL INTERNATIONAL POUR L’EXPLORATION DE LA MER CHARLOTTENLUND SLOT - DANEMARK Décembre 1979 RAPPORTS ET PROCÈS-VERBAUX DES RÉUNIONS VOLUME 175 POPULATION ASSESSMENTS OF SHELLFISH STOCKS A Special Meeting held in Charlottenlund, 29 September-1 October 1976 Edited by H. J. THOMAS CONSEIL INTERNATIONAL POUR L’EXPLORATION DE LA MER CHARLOTTENLUND SLOT - DANEMARK Décembre 1979 Imprimerie Bianco Luno A/S Copenhague TABLE OF CONTENTS Page Introduction, by H. J. T h o m a s............................................................................................................. 7 GENERAL Population dynamics and management of shellfish stocks, by D. A. Hancock....................... 8 MOLLUSCS COLLECTION FISHERIES Fishing power of divers in the abalone fishery of Victoria, Australia, by K. Beinssen 20 Measurement of natural mortality in a population of blacklip abalone, Notohaliotis ruber, by K. Beinssen and D. Pow ell............................................................................................................... 23 The estimation of fishing mortality of abalone based on experiments to measure the rate of reef coverage by the fishing fleet, by K. Beinssen............................................................................ 27 Données pour l’application des modèles de production à l’étude d’une population de Venerupis decussata (L.) exploitée dans la Baie de Santander (nord de l’Espagne), par C. A. Fernåndez P a to ............................................................................................................................ 30 Evaluation of cockle stocks in Ria de Faro - a preliminary report, by P. Soares Ferreira, R. A. Cachola and M. da Graça Pestana......................................................................................... 34 The assessment of commercial populations of the edible bivalve, Cardium edule, by A. Franklin and G. D. Pickett............................................................................................................... 38 OYSTERS The biology of the oyster, Ostrea lutaria, and the oyster fishery of Foveaux Strait, by H. J. Cranfield............................................................................................................................................ 44 A dredge survey of the oyster population in Foveaux Strait, by R. L. Allen and H .J . Cranfield.......................................................................................................................... 50 Mark-recapture surveys of the Foveaux Strait dredge oyster (Ostrea lutaria) population, by H .J . Cranfield and R. L. A llen.................................................................................................. 63 A yield model for the Foveaux Strait oyster (Ostrea lutaria) fishery, by R. L. A llen.............. 70 SCALLOPS Collecte de naissain de pectinidés en Bretagne, par D. Buestel, J. C. Dao et G. Lemarié .. 80 La croissance de la coquille Saint-Jacques (Pecten maximus (L.)) dans les divers gisements français, par L. Antoine, P. Arzel, A. Laurec et E. M orize...................................................... 85 Population abundance and dredge efficiency studies on the scallop, Pecten maximus (L.), by J. Mason, C. J. Chapm an and J. A. M. K in n ear....................................................................... 91 Long-term trends and evidence for production cycles in the Bay of Fundy scallop fishery, by J. F. C addy........................................................................................................................................ 97 Population assessment of the Georges Bank sea scallop stocks, by J. A. Posgay....................... 109 A comparison of exploited populations of the scallop, Pecten maximus (L.), by J. Mason, M. D. Nicholson and A. M. S h an k s................................................................................................... 114 An evaluation of the surf clam population and fishery in the mid-Atlantic Bight, by A. S. Merrill, Sukwoo Chang, and J. W. Ropes (abstract only) .......................................... 121 GENERAL DISCUSSION ON MOLLUSC POPULATION STUDIES.......................................................... 122 !* Page CRUSTACEANS ABUNDANCE AND DENSITY Catch and effort data of the lobster fishery in southeastern Norwegian waters during 1928 to 1975, by S. T v e ite ................................................................................................................ 123 Some observations on populations of Norway lobster, Nephrops norvegicus (L.) using diving, television and photography, by C. J. Chapman.................................................................. 127 Density of shrimp (Pandalus borealis) in Greenland waters observed by means of photo­ graphy, by P. KanneworfF................................................................................................................... 134 Recruitment to the catchable stock of the western rock lobster Panulirus longipes cygnus George, by R. G. Chittleborough and B. F. Phillips...................................................................... 139 CATCHABILITY AND EFFORT Some possible factors governing the catchability of Norway lobster in the Kattegat, by O. Bagge and S. M unch-Petersen..................................................................................................... 143 Preliminary assessment of effective effort in a two species trawl fishery for penaeid prawns in Shark Bay, Western Australia, by N. G. Hall and J. W. P enn........................................... 147 GROWTH Growth curve of tagged lobsters (Homarus gammarus') in Norwegian waters as inferred from the relative increase in size at moulting and frequency of moult, by G. Y. Conan and K. R. G undersen..................................................................................................................................... 155 Estimation of mortality and growth parameters from the length frequency of a catch, by D. G. Powell............................................................................................................................................. 167 Growth studies on the prawn, Nephrops norvegicus, by J. P. H illis............................................... 170 The use of length frequency distributions for age determination of Nephrops norvegicus (L.), by M. D. Nicholson................................................................................................................................ 176 MATURITY SIZE Linear growth stages in the rock lobster (Panulirus versicolor) as a method for determining size at first physical maturity, by R. W. George and G. R. Mo rg a n ...................................... 182 FISHING POWER The problems of pot immersion time in recording and analysing catch-effort data from a trap fishery, by D. B. Bennett and C. G. B row n........................................................................... 186 Soak time and the catch per pot in an offshore fishery for lobsters (Homarus americanus), by B. E. Skud ...................................................................................................................... 190 Trap response and the measurement of effort in the fishery for the western rock lobster, by G. R. M organ................................................. 197 RECRUITMENT The influence of variations in the seasonal temperature regime on survival of larval stages of the American lobster (Homarus americanus) in the southern Gulf of St Lawrence, by J. F. C addy................................................................................................................................................ 204 PARAM ETERS AND ASSESSMENTS Natural regulation of the population of Panulirus longipes cygnus George and responses to fishing pressure, by R. G. C hittleborough..................................................................................... 217 Some results of tagging experiments on the edible crab (Cancer pagurus) in Norwegian waters, by K. R. G undersen.............................................................................................................. 222 Estimates of abundance and recruitment to the standing stock for a Newfoundland population of the lobster, Homarus americanus, with a method of estimating its natural mortality, by G. P. E nnis..................................................................................................................... 225 Population assessment of the edible crab {Cancer pagurus L.) fishery off southwest England, by D. B. B en n ett..................................................................................................................................... 229 Page Research and management of the shrimp, Pandalus borealis, in Greenland waters, by D. M. Carlsson..................................................................................................................................... 236 Comparing several methods of assessing the maximum sustainable yield of Pandalus borealis in Arnarfjöröur, by U. S k ü la d ö ttir................................................................................................ 240 A quantitative study of the fluctuations of the stock of brown shrimp (Crangon crangon) along the coast of the Netherlands, by R. Boddeke and H. B. Becker.................................