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Discrimination of the Stock Complex of Atlantic Cod ( Gadus morhua ) off Southern Labrador and Eastern Newfoundland, as Inferred from Tagging Studies

1984; Volume: 5; Linguagem: Inglês

10.2960/j.v5.a19

1813-1859

William Lear,

Marine and fisheries research

During February-March 1978-81, about 25,000 Atlantic cod (;;;'45 cm) were tagged trom the prespawning concentrations on Hamilton Bank, Belle Isle Bank, Funk Island Bank and northern Grand Bank.There is evidence of a consistent annual pattern of migration to inshore waters during summer and to offshore areas during winter for each group of cod tagged along the outer continental shelf.The Hamilton Bank component evidently contributes to the southern Labrador and northeast Newfoundland coastal fisheries mainly from Notre Dame Bay northward.The Belle Isle Bank component migrates during summer mainly to southern Labrador, Strait of Belle Isle entrance and northeastern Newfoundland as far south as Notre Dame Bay.The pattern of movement is similar to that of the Hamilton Bank component except for a greater proportion in the Strait of Belle Isle.Cod on the northern and northeastern slopes of Funk Island Bank migrate during summerto eastern and southeastern Newfoundland, with smaller proportions going to southern Labrador and the Strait of Belle Isle than from the taggings on Belle Isle Bank.Cod from the southwestern slope of Funk Island Bank contribute mainly to the summer inshore fishery of Notre Dame Bay and Bonavista Bay and in a smaller degree to the fishery in Trinity Bay, Conception Bay and the eastern part of the Avalon Peninsula.Cod which overwinter on northern Grand Bank migrate southwards across the bank to the Virgin Rocks and tothe eastern slope of the bank.This component contributes mainly to the inshore fishery from Trinity Bay southward to SI. Mary's Bay, with little effect on the fishery north of Cape Bonavista.The evidence from tagging on winter concentrations is that each component contributes to the inshore fishery in specific, although wide, overlapping areas.Excessive exploitation of anyone component of the stock complex could have adverse effects on the inshore fishery in the areas frequented by the summer migrants.It is desirable, therefore that the offshore fishery in winter should be managed so that the inshore fishery in summer and autumn would not be affected detrimentally by excessive exploitation of a particular component of the stock complex in Div.2J, 3K and 3L.