The Atlantic cod is a highly migratory fish. Patterns of migrations differ somewhat between regions. This pattern is associated with reproduction and seasonal temperature change in the Newfoundland stock (Rose 1993). Here, huge schools of cod leave their wintering areas in deep, oceanic waters, and follow tongues of deep, relatively warm, oceanic waters (or highways) across the continental shelf to summer feeding areas nearer to the coast. Spawning occurs in dense concentrations (>1 fish/m3) as they begin this mass movement, with multiple pairs of spawning fish observed in columns above the mass. As this huge mass migrates inshore, it periodically encounters important prey aggregations (such as capelin or shrimp) and disperses in order to feed. The mass is led by the largest fish (or scouts), and the smallest bring up the rear. After reaching nearshore waters, they turn and move northward along the Newfoundland coast in late summer, then eventually return to their deep-water wintering areas.
Off New England, Atlantic cod typically move into coastal waters during the fall, and then retreat into deeper waters during spring. A slightly different pattern occurs in the Great
South Channel area where they move southwesterly during the fall, spend the winter off southern New England and the Middle Atlantic coast, and then reverse this movement during the spring.
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