Research Document - 2000/064

Assessment of the NAFO 4T southern Gulf of St. Lawrence herring stocks in 1999

By C.H. LeBlanc, G.A. Chouinard, and G.A. Poirier 

Abstract

Two estimates of the spring spawner component population size were calculated because of uncertainties related to the spring gillnet catch rates. The two estimates of the F_0.1 spring spawner fishing level for 2000 are 15,000 and 22,000 t. Risk analyses indicated that it would be prudent to set the TAC for 2000 closer to the lower estimate of 15,000 t. The estimate for 2000 from the previous assessment was 16,000 t. Reported 1999 landings of spring spawners were 17,304 t compared to the TAC of 18,500 t. Inshore catch rates in 1999 were the lowest in the time series. These catch rates likely underestimate biomass because industry reported that the fishery opened after herring had arrived on some spawning beds. The 1995 year-class (age 5) is near average and the 1996 year-class (age 4) is estimated to be near the second largest in the time series since 1978. The age 4+ exploitation rate has been at or below the target rate in recent years. Abundance of herring that spawn during the spring in Chaleur Bay has declined during the last six years and continued to be low in 1999.

The best estimate of the F_0.1 fishing level for fall spawner component in 2000 is 71,000t. This level takes into account the tendency to over-estimate age 4 fall spawners. The 1995 year-class was estimated to be the highest since 1978, while the 1994 year-class was estimated to be the second highest. The acoustic and bottom trawl survey indices are at moderate levels and opinions of abundance expressed during the phone survey of the inshore fleet generally indicated an increase in abundance from 1998 to 1999. The inshore gillnetter catch rates were the highest since 1978. Reported 1999 landings of fall spawners were 54,441 t compared to the fall spawner TAC of 60,500 t. There were no 4T herring caught in the 1999 overwintering fishery in 4Vn, while in 1998, this fishery recorded the lowest catch (<100 t) since 1978. Participants in the fishery reported for the second year in a row that this was the result of high numbers of small fish and herring being inaccessible to the gear, rather than a problem with abundance. The age 7+ exploitation rate in 1999 was slightly below the target. 

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