Bycatch in an experimental fishery for Patagonian toothfish (Dissostichus eleginoides, Nototheniidae) in Ecuadorian oceanic waters

Abstract

The objective of this paper was to characterize bycatch in an experimental fishery for Patagonian toothfish in Ecuador during 2017-2021. Diversity was analysed using Shannon, Margalef, Simpson, and Dominance indices. Bycatch representativity was calculated as the difference percentage between the target catch and non-target, in weight. The bycatch comprised 51 taxa and was composed primarily of fish. In addition, 12 species of pelagic habits (i.e. fishes and sharks) were also captured during the deployment/retrieval of fishing gear. The most frequent species (by number of individuals) were chimaeras (Hydrolagus melanophasma), grenadiers (Antimora rostrata, Coryphaenoides delsolari, and Coryphaenoides armatus), and sharks (Etmopterus granulosus and Centroscymnus owstonii). The diversity was medium low, according to the Shannon indices (0.5-1.8), with a negative trend for dominance and a positive trend for equitability.