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Research Document - 1999/044

Relative strenght of the 1998 year-class, from nearshore surveys of demersal age 0 Atlantic cod in 3KL and in Newman Sound, Bonavista Bay

By Robert S. Gregory, David A. Methven, David C. Shneider and Danny W. Ings

Abstract

Recruitment of age 0 Atlantic cod to the nearshore in 3KL in 1997 was the highest on record during the annual Fleming survey in the 1990's (Methven et al. 1998). This survey was not conducted in 1998. In its absence, we conducted a qualitative assessment of the strength of the 1997 and 1998 year-classes based on abundance of demersal age 0 and age 1 Atlantic cod in the nearshore in Newman Sound, Bonavista Bay in the summer and fall 1998. Three years of data from Newman Sound were available- 1995, 1996, and 1998. We compared abundances of age 0 and age 1 Atlantic cod in Newman Sound in 1998 to those in previous years and with those reported during the Fleming surveys (1992-97). The sampling techniques used during both surveys were identical and data were available for the same times in the fall for use in interannual comparisons (early to mid-October). Therefore, abundance data from the two surveys were comparable, albeit at different spatial scales. We observed good correspondence of abundance trends for both age groups between the surveys in 1995 and 1996. In both data sets, 1996 showed the lowest age 0 abundance among years. The Fleming survey results for 1997 predicted that age 1 abundance in 1998 would be higher than in previous years this decade. High age 1 abundance in 1998 compared to previous years in Newman Sound supported this prediction. Age 0 Atlantic cod abundance in 1998 was over double that in 1995 and a full order of magnitude higher than in 1996. We suggest that the 1998 year class will be stronger than either the 1995 or 1996 year-classes. Analysis of length frequency data collected from July to November in Newman Sound indicated that age 0 Atlantic cod settled in the nearshore in two distinct recruitment pulses in 1998 - the first arriving in early August, the second in late September. In both 1995 and 1996, only the second of these pulses was evident. The implications of each of these pulses on overall recruitment to subsequent age groups remains to be identified.

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