Atlantic Cod Populations along the Southern Canadian Mainland as shown by Vertebral Count Studies

Abstract

Analysis of vertebral counts of 28,097 cod (Gadus callarias L.) in 184 samples from the Canadian mainland coast demonstrates some segregation of inshore and offshore populations and little mixing between the cod on various sections of the coast. Four populations are recognized in the Gulf of St. Lawrence. Three offshore populations and at least four inshore populations are also recognized along the south coast of Nova Scotia. Seasonal migrations northward in summer and southward in winter are indicated by changes in vertebral numbers. Small cod (less than 21/2 lb.) exhibit less variability in vertebral number than larger ones, suggesting increased mixing with growth.