Analysis of fishing strategies by trawl vessels in the Gulf of Alaska; A temporal and spatial comparison of trip vs. haul-specific targetting

The term "fishery" is commonly used in fishery science literature to generally describe the interaction between vessel activity and the type(s) of fish being caught.  However, the term is ambiguous in its meaning and difficult to quantitatively define.  National Marine Fisheries Service, Alaska Region uses an algorithm to approximate species targeted in a fishery based on the predominance of species that are retained by a vessel during a fishing trip.  This assigned target is used to identify fisheries and calculate catch.  However, operators of vessels must consider a variety of regulatory and marketing constraints when harvesting groundfish.  Thus, operators are likely pursuing multiple targets and avoid certain species to maximize the harvest of economically desirable species.  This study explored the variability of groundfish catch within a trip for trawl vessels in the Gulf of Alaska.  Variability was explored by assigning targets to hauls observed by the North Pacific Observer Program and using GIS to spatially describe haul-specific targets during a trip.  Results show that vessels differentially target species within a trip and, at times, move between fishing grounds in an effort to optimize catch.  This may have implications in making estimates of catch based on trip target only.