Movement, Mortality, and Size Selectivity of Sport- and Trawl-Caught Lingcod off Washington

Movement, size selectivity, and fishing mortality parameters of lingcod Ophiodon elongatus were estimated for the sport and trawl fisheries off Washington by using mark–recapture data from 1991 to 1994. Parameters were estimated with a multiple-year tag release sample design by maximizing the likelihood of the observed tag recoveries via the method of tuned simulation. The results confirm the open nature of the coastal lingcod population: lingcod found near shore became vulnerable to the trawl fishery off shore, though very few lingcod found off shore became vulnerable to the sport fishery near shore. The relatively greater selectivity of small female lingcod estimated by this study, compared with estimates from a previous catch-at-age analysis, suggests the possibility of undocumented discard mortality in the trawl fishery. Previous mark–recapture fishery interaction studies required independent estimates of fishing mortality to estimate movement rates. This study shows that both fishing mortality and selectivity can be estimated for a two-fishery interaction model with 3 years of tag releases and 4 years of tag recaptures when sufficient numbers of tag recoveries are available for all strata.