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Bank-scale migration patterns in northern cod

1997; Elsevier BV; Volume: 44; Issue: 12 Linguagem: Inglês

10.1016/s0967-0653(97)88984-3

1878-6731

Christopher T. Taggart,

Marine and fisheries research

Proper resolution of population structure is necessary not only for the interpretation of temporal and spatial variations in the biology of a species, but also for successful management. This is particularly true for the seriously depleted northern cod (Gadus morhua) stock complex (NAFO Divisions 2J, 3K, and 3L). In this paper, data collected over the last three decades from tagging studies conducted in winter on Hamilton and Belle Isle Banks and in the North Cape region of the northern Grand Bank, are employed to assess migration patterns in northern cod and to compare those patterns to the population structure described in recent genetic studies cAwainonducted on populations from the same regions. The results reveal that the average geographic distribution of cod tagged in the vicinity of Hamilton Bank in winter overlaps in the offshore winter distribution with those tagged on Belle Isle Bank, showing the populations can intermingle during the offshore spawning period. The average geographic distribution of cod tagged in winter in the North Cape region did not overlap with those fish tagged on either Hamilton or Belle Isle Bank. Likewise, the average winter distributions of cod from the latter two banks did not overlap with those from the North Cape area. These results are entirely consistent with recent and earlier genetic studies of populations from the same regions and suggest that the northern cod stock complex is comprised of at least two discrete offshore populations. The results from this study are used to present a testable hypothesis to explain anomalous distributions in recent years for northern cod in the offshore and inshore areas of Newfoundland.