"Preliminary Results from an Age-Structured Simulation Model of Pacific Sleeper Shark Population Dynamics in the North Pacific Ocean"

Preliminary results will be presented from an age-structured simulation model of the population dynamics of Pacific sleeper sharks in the North Pacific. Pacific sleeper sharks inhabit the continental shelf and upper continental slope of the eastern Bering Sea and Gulf of Alaska where they are captured incidentally in commercial fisheries for groundfish. The relative abundance of Pacific sleeper sharks has increased significantly in fisheries-independent bottom trawl and longline surveys for groundfish in the Gulf of Alaska between the years 1984 – 2003. Whether the increasing trends in relative abundance represent an increase in absolute population size or a shift in population distribution could not be determined from the limited available data. In this study, age-structured simulation will be used to evaluate the plausibility of the observed trends in relative abundance and to identify data gaps and research priorities for Pacific sleeper shark stock assessment in the Gulf of Alaska. The age-structured simulation model will incorporate the assumed life history characteristics of Pacific sleeper sharks including slow growth, long life, late maturity, and a low reproductive rate. Model results will be evaluated for sensitivity to key uncertainties in life history and stock structure including maximum size, the shape of the length-based selectivity curve, the steepness of the stock-recruitment relationship, and recruitment variability.