Abstract
Maturity at size and age of Greenland halibut in the Canadian north-west Atlantic were investigated using three separate data sources: (1) Canadian fall research vessel surveys from 1978 to 1994 in NAFO Div. 2J and 3K; (2) Canadian deep water surveys in NAFO Div. 3K, 3L and 3M in 1991, 1994 and 1995; and (3) Canadian commercial deep water gillnet fishery in 1993 and 1994 in Div. 0B, 2G, 2H, 3K and 3L. Estimated proportion of fish mature in each length group showed large spatial and temporal variability from all data sources. Proportions mature at age (only available from the Canadian deepwater surveys) also exhibited inconsistency with the age at 50% maturity ranging from 9.5 to 15.0 years for females and from 8.2 to 11.6 for males. There were no apparent trends in this variation, which may be a result of irregularities in the maturation process and spawning of Greenland halibut, leading to variability in the distribution of adult fish. The inavailability of precise estimates of maturity at age and size will make the measurement of the effect of fishing practices on spawning stock biomass and yield per recruit and/or advice on minimum fish size to protect juveniles extremely difficult. A synoptic survey of the entire stock area may be the only way to obtain an accurate reflection of the maturity schedule of the population.
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