Research Document 1997/125

The Scotian Shelf shrimp (Pandalus borealis) fishery in 1997

By P. Koeller, M. Covey, K. King

Abstract

The total biomass estimate in 1997 is the highest on record, but the increase above previous levels is entirely due to an increase in the inshore stratum. Biomass in the offshore strata has remained high and stable at around 28,000 metric tons since 1995. Both commercial CPUE series give 1997 values that are about the same as in 1996 and indicate, as do survey results, that the biomass increase of recent years has stabilized. Changes in the distribution of fishing effort in 1996 and 1997 plus anecdotal information indicated that fishers were targeting larger animals in 1997. Survey population estimates suggest that the 1995 and 1996 year classes may be weak, but this must be confirmed by subsequent surveys. If confirmed this should not affect the fishery until 1999 because of the strong 1993 and 1994 year classes and accumulated biomass in the 3+ age groups. The potentially weak 1995 and 1996 year classes are not due to decreased spawning stock biomass, or increased fishing effort, but rather may be due to increases in egg disease caused by increased densities. Reproductive capacity in terms of the percent of females that are ovigerous has remained about the same both inshore and offshore since monitoring began. The Chedebucto Bay trap fishery took about 300 tons during its first full fishing season (summer 1996 to spring 1997), considerably less than the provisional TAC of 500 tons. Catch rates dropped substantially after the new licences were introduced because of their restricted fishing area within Chedebucto Bay. A new fishery in Mahone Bay during 1997 exploits a different stock than that fished by trappers in Chedebucto Bay. Bottom temperatures increased on the inshore and offshore shrimp grounds by about 1 °C in 1997, but are still within the optimum for the species. Continued increases could have a negative impact on recruitment.

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