Catch and Effort Estimation for Puget Sound Marine Sport Fisheries

Since 2003, recreational catch and fishing effort in Puget Sound has been estimated using a combination of two independent surveys. An access point intercept survey provides data used for estimation of catch rates and for calculating proportions of unlicensed anglers. A telephone survey of licensed anglers is used to estimate fishing effort. Estimates of fish harvested and released are derived from the catch rates and effort estimates from the two surveys. In 2009, the estimation procedure was revised to address estimation problems due to sparse and missing data. The revised method reduces the missing data problem by reducing the number of variables used in domain definition. To develop a imputation strategy for the missing data, General Linear Models (GLM) were used to fit the intercept survey data for each species groups to identify the explanatory variables that are influential to catch rate variability: fishing areas, time (year, bimonth), and target species (salmon, bottom fish, halibut, other). Relative mean square error was used to gauge the level of influence of the individual factors. Model results indicate that “year” is least influential factor next to “bimonth” factor across species groups, suggesting missing data imputation should be made from adjacent time periods, rather than adjacent fishing areas or another target species. Modifications were made to the intercept survey schedule to ensure coverage of all fishing areas.