Research Document 1997/107

Assessment of 4X haddock in 1996 and the first half of 1997

By K.T. Frank, R.K. Mohn, and J.E. Simon

Abstract

The 4TVW haddock fishery was essentially closed in 1994 with reported total landings of just over 100t. Strict by-catch restrictions were in place for those fisheries (such as flatfish) operating in the area in 1995 and 1996 resulting in total landings of 135 and 133t respectively. The year-round nursery ground closure (mainly Emerald and Western banks) imposed in 1987 remains in effect to present. Given the severely restricted nature of the fishery in the recent past, it is difficult to compare the distribution of landings by gear type with those of previous years.

Resumption of routine ageing for this stock has resulted in the application of the standard age-based population analysis (SPA) of the stock. Abundance estimates indicate the population is near to historic low levels. The 3+ biomass in 1996 is about 23,000t and the 5+ biomass is about 13,000t; the 3+ and 5+ biomass reflects the range of current spawning stock biomass. Recruitment estimates for the 1989 to 1993 yearclasses are below the long-term average of 28 million fish and this has contributed to the current low spawning stock biomass. The 1988 yearclass was the last large pulse of recruitment seen in this stock and with its gradual disappearance the stock is expected to continue to decline.

Substantial long-term declines in size at age are evident in haddock age 3 and older and size at age is at a minimum in the 1990s for ages 4 to 11 years old. The potential for fish to grow large in this haddock stock is currently quite low and at present very few fish in the stock are larger than 45 cm. Total mortality estimates derived from the July survey have been relatively stable since 1992 with an average of about 0.4. Total mortality should approximate natural mortality in a closed fishery suggesting the assumed level of natural mortality of 0.2 for this stock may be too low.

The short-term prospects for this stock are not encouraging although some improvement in recruitment has been seen in the most recent years in the summer survey series to near-average levels (1993 and 1994 yearclasses). These yearclass could contribute to stock rebuilding. However, the current growth, condition and reproductive potential of the stock appears to be quite low and the population may not respond as expected to a regime of little or no commercial exploitation.

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