Research Document - 2004/099

Assessment of pollock in 4VWX5Zc using a Framework Approach

By Neilson, J.D., P. Perley, S. Gavaris

Abstract

A comprehensive review of assessment methodology (referred to here as a Framework Assessment) was completed in 2004, and included inputs up to and including 2002. This assessment updates the results with 2003 indices and catch, and provides advice for the two stock components comprising the pollock resource in the Canadian Maritimes. The fishery is currently focused almost exclusively on the western component. For the western component, fishing mortality has steadily increased from the early 80s until 1994, when severe quota restrictions commencing in 1992 halted the increase. Quotas were relaxed again in 1998, causing a rapid increase in F. Subsequent reduced quotas and harvests have contributed to the decline in fishing mortality, which remains above the target level, particularly for the older ages. Population biomass was at its highest level in 1984, then steadily declined until 1999. Biomass has been rebuilding since, but remains at a low level compared with 1984. The 1998 and 1999 year-classes have helped the population recover somewhat, but the preliminary estimate of the 2000 year-class indicates that it is comparatively weak. The Framework Assessment examined yield per recruit analyses and stock-recruitment patterns to derive a fishing mortality reference point of F_ref=0.2. When stock biomass is less than 30,000 t, exploitation may be further constrained to achieve rebuilding. While the population has a high likelihood of achieving a 10% increase in biomass over the 2005/06 fishing year with removals as high as about 4500 t, the range of harvest strategies in the fishing year that are risk averse (25% risk of exceeding F_ref) to risk neutral (50% risk of exceeding F_ref) are about 2200 to 2900 t.

For the eastern component, indices from the summer research vessel surveys, while extremely variable, indicate that total mortality is high and increasing, even with relatively small landings from the fishery. Large scale directed pollock fisheries should not be considered until the eastern component recovers.

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