Certain biological characteristics of Greenland halibut in the northwest Atlantic and their significance for stock identification

Bowering, W. R. (1982) Certain biological characteristics of Greenland halibut in the northwest Atlantic and their significance for stock identification. Masters thesis, Memorial University of Newfoundland.

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Abstract

Greenland halibut (Reinhardtius hippoglossoides, (Walbaum)) are distributed throughout the Canadian Northwest Atlantic from Baffin Bank to the northern Grand Bank and into the Gulf of St. Lawrence. Larger older fish are found in deeper waters than the smaller fish and are more abundant in the more northerly areas. Analysis of growth rates indicated that the largest size at age for Greenland halibut is in the Gulf of St. Lawrence with the smallest size at age associated with Baffin Bank. Average sizes at age for intervening areas were generally similar. Probit analysis on female maturity indicated that fish in the Gulf of St. Lawrence mature at a much smaller size than other areas. In the Labrador area size at 50% maturity decreased progressively moving northward. Fish fecundity was also found to be significantly higher for the same size fish in the Gulf of St. Lawrence compared with those of southern Labrador area size at 50% maturity decreased progressively moving northward. Fish fecundity was also found to be significantly higher for the same size fish in the Gulf of St. Lawrence compared with those of southern Labrador. Tagging studies in eastern Newfoundland inshore indicate that Greenland halibut migrate towards deeper water and northward to Davis Strait. Young Greenland halibut move towards the coastal areas in summertime as part of a feeding migration. Based on the analyses of these biological characteristics, two separate spawning stocks of Greenland halibut are identified. One stock is comprised of fish from the northern Grand Bank to Davis Strait where spawning occurs, the second in the northern Gulf of St. Lawrence with spawning occurring southwest of St. George's Bay in the Laurentian Channel.

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