UW Aquatic & Fishery Sciences Quantitative Seminar

John Wallace

NOAA Fisheries, Northwest Fisheries Science Center

A fishery-independent estimate of recent population trend for bocaccio rockfish (Sebastes paucispinis) in the Southern California Bight

Abstract

Fishery-independent surveys are an important source of information for stock assessment and management worldwide. Research surveys often use trawl gear to capture commercially valuable species and calculate indices of relative abundance or density. However, many species of interest do not occur in direct contact with the bottom, or occur in areas where high-relief habitat precludes trawl operation. This analysis introduces a standardized hook-and-line survey for rockfish conducted by the Northwest Fisheries Science Center in the Southern California Bight. The survey uses rod-and-reel fishing gear similar to that used in many recreational fisheries to sample nearly 100 locations covering a wide range of depths and habitats. To provide an example of how these data can be analyzed for direct inclusion in stock assessments, we standardize catch rates of bocaccio rockfish from 2004 - 2007 using a Bayesian Generalized Linear Model to account for site, fishing time, survey vessel, angler, and other effects. Results are more precise than other indices of abundance that are currently available and indicate the bocaccio stock in the southern California Bight has shown a relatively flat trend over recent years. This survey is likely to be the only available tuning index for recent years as historically-used recreational catch per unit effort indices have been largely compromised due to changes in bag-limits and other management restrictions.