Atlantic Fisheries Research Document 1996/092

Temporal trends in the age and length at maturity of Atlantic cod (Gadus morhua) from NAFO Subdivision 3Ps

By J. Brattey; M.J. Morgan

Abstract

This study presents a time series of observed and estimated proportions mature at age and length for female and male cod form NAFO Subdivision 3Ps from 1972 to 1996. The proportion of fish maturing at an early age or shorter length has been increasing among cod in this management unit from late 1980s until the early to mid 1990s; however, estimates for the last few years suggest that the declining trend has reversed or at least halted. The estimated age at 50% maturity for females declined from a high of 7.2 yr during 1988 to a low of 5.0 during 1994, with the most recent (1996) value at 5.54. Among males, the corresponding values were a high of 5.89 during 1987, a low of 4.55 during 1992, with the most recent value at 4.87. Median length at maturity shows a similar trend with females declining from a high of 63.18 cm during 1988 to a low of 46.72 during 1994 with the current value at 47.81. Males declined from a median length at maturity of 57.38 during 1979 to a low of 42.35 during 1994 with the current value at 43.41. We found no evidence for differences in age at maturity between cod sampled during bottom trawl surveys in 3Ps during 1995-96 and cod sampled inshore during the 1995 Sentinel Survey in 3Ps during the spring and fall 1995.

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