Research Document - 2003/005

An Assessment of the Eastern Scotian Shelf Shrimp Stock and Fishery for 2002

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

Abstract

The DFO-industry survey index decreased in 2002 for the third consecutive year. The strong 1995 year class continued to support the fishery in 2002, however, subsequent years classes have been weaker and the total population is declining from the historic high levels of the late 1990s. Strata 13 (Louisbourg Hole), 15 (Canso Hole) and 17 (inshore) have all declined to the lowest levels since the DFO-industry survey series began in 1995. In contrast, Stratum 14 (Misaine holes) has continued to increase, with the last two years showing the highest abundances on record. The distribution of commercial effort reflects the changing distribution of biomass, with the highest proportion of the catch coming from SFA 14 for the first time since 1998. Survey and commercial catch rates again diverged in 2002 with commerial cpue continuing to increase due to the aggregation of the remaining biomass in dense concentrations. Spawning stock biomass remains high, and the area with the lowest exploitation rate (SFA 13) is experiencing declines similar to the more heavily fished areas. Conversely, Area 14, which has experienced among the highest exploitation rates during the last 8 years has continued to increase. Although the recent declines appear to be environmentally driven there are concerns that the combined negative effects of fishing and environmental influences could accelerate the observed biomass decreases in most areas and perhaps bring about a decline in SFA 14 prematurely, and prolong recovery. Increases in female exploitation, fewer larger females in the population due to removals by the fishery, increased fishing during the ovigerous period and decreases in the size at transition and maximum sizes may have been impacting negatively on the population's reproductive capacity in recent years, however the 40% decrease in TAC in 2002 appears to have had the desired effect and reversed or stabilized some of these trends. In addition, results from 'belly bag' samples suggest that the 2001 year class is strong. The Traffic Light analysis shows a marked improvement over previous years - 10 of the 23 indicators were green and only 3 were red in 2002 compared to 7 green and 10 red in 2001.

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