Relationships among temperature, depth, and abundance of commercially important fish captured by trawl vessels in the Kodiak area of the Gulf of Alaska, USA

Abstract

Increased understanding of the factors influencing fish distributions and abundance may improve fisheries management and stock assessment models and may provide the fishing industry with a means to reduce bycatch. I investigated the associations of ambient seawater depth and temperature with catches of commercially important species in the Gulf of Alaska. Time-depth recorders were attached to trawl nets to collect depth and temperature data during commercial bottom trawl fishing operations. The data collected from these recorders were combined with species composition data collected by onboard observers to determine associations between these physical variables and catch of fishes. Parameters for depths and temperatures where target species were abundant were identified. Pacific cod were captured in abundance in depths shallower than 130 m while withstanding water temperatures ranging from 2.8 to 8.5°C. Rockfishes were abundant in depth ranging from 52 m to 353 m and temperatures ranging from 4.9 to 8.3°C. Shallow-water flatfishes were captured in abundance in depths shallower than 97 and temperatures from 2.6 to 10.7°C. Deep-water flatfishes were abundant in depths greater than 115 m and water temperatures ranging from 3.8 to 6.5°C. Arrowtooth flounder, Pacific halibut, and walleye pollock were found in all temperatures and depths analyzed.