Research Document - 2003/040

Assessment of the NAFO 4T southern Gulf of St. Lawrence herring stocks in 2002

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

Abstract

A population analysis was conducted on the 2002 4T herring spring spawner component using sequential population analysis (SPA). The analysis included the gillnet catch rates abundance index (CPUE) and the acoustic survey index, using intrinsic weighting. The estimated F0.1 catch for the spring spawner component in 2003 was 14,000t. Reported 2002 landings of the spring spawner component were 9,210t against a total allowable catch (TAC) of 8,000t. Inshore catch rates in 2002 were similar to those from 1999 to 2001; these were the lowest since 1990. Year-classes produced after 1991 were estimated to be below average. The 1998 year-class was estimated to be low, however indications from the fishery and experimental net fishing suggested that this may be an under-estimate. Age 4+ spawning biomass has declined since 1995 and was estimated to be 51,000t at the beginning of 2003. The exploitation rate for the fully recruited ages of 6 to 8 was slightly below the target set in 2002. The 2002 4T herring fall spawner component assessment was based on a sequential population analysis (SPA) using the gillnet catch rates abundance index (CPUE). After adjusting for the tendency to overestimate fall component population numbers, the estimated catch at F0.1 for 2003 was 65,500t. Reported 2002 landings of the fall spawner component were 50,642t against the fall spawner TAC of 51,500t. There was no fishery in the 4Vn (Area 17) overwintering area. Inshore catch rates in 2002 were similar to 2001, which were among the highest in the time series starting in 1978. The 1995, 1996 and 1998 year-classes are estimated to be well above average. Estimates of population biomass and abundance are currently high, however retrospective patterns indicated a tendency to overestimate the size of the biomass in the current year. The age 7+ exploitation rate in 2002 was estimated to be below the target.

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