Effects of setting time, setting direction and soak time on longline catch rates

Abstract

Most studies of factors affecting catching efficiency and selectivity in longlining have focused on various gear parameters (mainline and snood material, hook design and size, rigging) and on the bait (type and size), and few studies have investigated how catch rates are affected by the way the gear is operated during fishing. We carried out fishing experiments to study the effects of setting time, setting direction (relative to the current direction) and soak time on catch rates of cod (Gadus morhua) and haddock (Melanogrammus aeglefinus). Lines set before dawn and lines set across the current gave higher catch rates of haddock than lines set after dawn and in the same direction as the current, respectively. Similar effects were not found for cod, and these differences between haddock and cod were explained by differences in behaviour and interspecific competition for the available baits. Soak time was not found to significantly affect the catch rates of either species, indicating that other factors have a more pronounced effect on longline catch rates and may therefore mask the effect of soak time.