Oceanographic determinants of ocean sunfish (Mola mola) and bluefin tuna (Thunnus orientalis) bycatch patterns in the California drift gillnet fishery

The reduction of incidental capture of non-target species in a fishery (bycatch) is a key objective of ecosystem-based fisheries management (EBFM) and critical to the conservation of many marine species. Predicting bycatch events can inform targeted ecosystem-based management approaches to reduce risk. Here, the probability of ocean sunfish (Mola mola) and bluefin tuna (Thunnus orientalis) bycatch in the California large-mesh drift gillnet fishery is predicted using a suite of remotely-sensed environmental variables. Generalized additive models (GAMs) were used to model bycatch probability for these species in 8045 observed sets from 1990 to 2011, and predictive capabilities were assessed using k-fold cross validation.Bycatchprobabilities for bothspecies were elevated inregions of cool sea surface temperatures (