Movement dynamics of tagged sablefish in the northeastern Pacific

Abstract

Listen

Translate article

We used a Markov model to quantify movement rates of tagged sablefish ( Anoplopoma fimbria) among regulatory areas of the North Pacific Fishery Management Council during 1979–1987. The model included natural and fishing mortality, tag reporting and shedding rates, and movement probabilities. Maximum likelihood was used to estimate the parameters of the model. Estimated annual movement rates out of an area were in the range 19–69% for small (less than 57 cm fork length (FL)), 25–72% for medium (57–66 cm FL), and 27–71% for large (more than 66 cm FL) sablefish. The predominant direction of movement along the continental slope was eastward for large sablefish and westward for small sablefish. Most estimates of movement rates were precise, unconfounded, and robust to perturbations of input constants (natural and fishing mortality, and tag reporting rates), except for some imprecise estimates of large sablefish. The results indicate that movement plays an important role in determining the amount of sablefish available for harvest in an area. To account for the interactions among fisheries in different areas, the movement dynamics of sablefish should be incorporated into a stock assessment based on size or age-structure.