Determinants of Catching Power in the British Columbia Salmon Purse Seine Fleet

Abstract

We show that vessel attributes such as age, length, tonnage, and horsepower will account for less than 10% of the differences in catch between vessels in the British Columbia salmon purse seine fleet. The vessel effect is defined as repeatable differences in catch between vessels. This effect accounts for 30–34% of the differences, and we infer that the unmeasured skipper, crew, and net effects are responsible for 20–24% of the variance in catch. Vessels are specialized by area, with many boats performing well in one area and poorly in another. When fishing area is added as a treatment, area specialization accounts for roughly half of the vessel effect. In fisheries where local knowledge and experience are important, attempts to calibrate catch per unit effort data based on vessel attributes may not work well if skipper skills are a major determinant of catch. Additionally, skipper skill will greatly impede attempts to reduce catching power by elimination of vessels through buy back proposals, since vessels, and not skippers, will be eliminated.