Research Document - 2001/045

Assessment of the 4T southern Gulf of St. Lawrence herring stocks in 2000

By LeBlanc, C.H., G. A. Chouinard and 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 12,500 t. Risk analyses indicated that at a catch of 12,500t in 2001, there is a 50% probability of exceeding F0.1.. The estimates for 2000 from the previous assessment were 17,000t to 25,000t. Reported 2000 landings of spring spawners were 16,730 t compared to the TAC of 16,500 t. Inshore catch rates in 2000 were the second lowest since 1990. The 1999 spring catch rates, though lower, were considered to be an underestimate because the fishery opened after herring had arrived on the spawning beds. Year-classes produced after 1991 are average or below average. The spring spawner component age 4+ exploitation rate was above target in 2000.

The best estimate of the F0.1 fishing level for fall spawner component in 2001 is 60,500t. This level takes into account the tendency to over-estimate age 4 fall spawners. The 1995 and 1996 year-classes are estimated to be the most abundant since 1978. The acoustic index indicated that abundance was similar to 1999. Opinions of abundance expressed during the phone survey of the inshore fleet generally indicated an increase in fall abundance from 1999 to 2000.

Inshore catch rates of the fall spawner component in 2000 were equal to 1999, and these were the highest in the time series that started in 1978. Reported 2000 landings of fall spawner component were 59,086t against the fall spawner TAC of 71,000t.

There were no 4T herring caught in the overwintering fishery in 4Vn. Participants in this fishery indicated that there was little effort put in searching for herring in 4Vn in 2000. The age 7+ exploitation rate of the fall spawner component in 2000 is below the target.

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