A new method for indexing spawning stock and recruitment in ocean shrimp, Pandalus jordani, and preliminary evidence for a stock-recruitment relationship

Using improved indices of age-1 recruitment and parent stock, the existence of a stock-recruitment relationship for ocean shrimp, Pandalus jordani was examined as were the effects of large catches of eggbearing shrimp in April on subsequent recruitment. After known environmental influences were accounted for, regression analysis revealed evidence of a quasilinear relationship between recruitment and either spawning stock or egg production. The stock-recruitment relationship showed that average recruitment increases if higher spawner abundance is maintained in years of low abundance. The recruitment-stock relationship, however, showed that low abundance of spawning fish was mostly a result of environmentally driven recruitment failures, rather than just fishery impacts. Fishing did contribute to the low numbers of spawning fish in 1993, and catches of egg-bearing shrimp in April 1989 may have also depressed the 1990 year class. The strong recruitment-stock relationship for ocean shrimp suggests that an increase in escapement of all ages of shrimp in response to a year-class failure may do more to bolster recruitment than traditional strategies aimed at protecting age-1 shrimp.