Research Document - 2002/053

Assessment of the NAFO 4T southern Gulf of St. Lawrence herring stocks in 2001

By C.H. LeBlanc, C. MacDougall, G.A. Poirier

Abstract

Two population analyses were conducted on the spring spawner component using virtual population analysis. The analyses differed in the abundance indices that were used in the model. The estimate of the F0.1 spring spawner fishing level for 2001 is 7,000 t. The estimate for 2001 from the previous assessment was 11,600 t. Reported 2001 landings of spring spawners were 14,598 t compared to the TAC of 12,500 t. Inshore spring catch rates in 2001 were similar to those in 1999 and 2000; these were the lowest since 1990. Year-classes produced after 1991 are average or below average. Age 4+ spring spawning biomass has been declining since 1995 and is estimated to be 20,000 t at the beginning of 2002. The age 7+ fully recruited exploitation rate was well above target in 2001.

The fall spawner component assessment is based primarily on the catch per unit effort (CPUE) index and estimates of total mortality calculated from the CPUE series. Total mortality for the last three years is estimated to have been very high. The 1995 to 1997 year-classes are above average. Current rates of removals would likely result in a rapid depletion of the stock at average recruitment. It is suggested that fishery removals in 2002 be reduced from those in 2001 by a minimum of 10 to 15%. If catch rates decline in 2002, further reductions to the catch may be required. The acoustic index indicated that biomass estimates of both spring and fall spawning components were lower than 2000. Opinions of fall abundance expressed by fishers during the annual phone survey of the inshore fleet indicated equal or higher abundance from 2000 to 2001, except for the Chaleurs Bay area where abundance was rated slightly lower. Fall inshore catch rates in 2001 were slightly less than in 2000, which were the highest in the time series starting in 1978. Reported 2001 landings of the fall spawner component were 52,125 t against the fall spawner TAC of 60,500 t. There was no fishery in the 4Vn overwintering area.

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