Bycatch reduction device in the Chilean hake (Merluccius gayi) bottom trawl fishery, using a rigid separation grid

The Chilean hake trawl fishery is one of the most emblematic fisheries in Chile. Considering the type of trawl gear used in the industrial fleet and the variety of species which cohabitates this target specie, discarding has become a recurrent practice, where the jumbo squid and the Chilean hake are often part of the discarded fauna. This problem has been monitored since the amendment of General Fisheries and Aquaculture Law in Chile in 2012, where a definition for discard was incorporated, regulations were modified and sanctions were established for those who engage in this practice. To date, the estimates of discards in this fishery have experienced a reduction from five to one thousand tons, decreasing the amount of discarded catch of Chilean hake and jumbo squid. This reduction is coincident with the introduction of the rigid separation grid in the bottom trawls of the vessels that adopted its use. This article describes the use of the rigid separation grid in trawl hauls aimed at Chilean hake, in which there were fewer hauls with the presence of jumbo squid and also reduced the capture and the catch per unit effort of this species. Besides, an experimental work, which involved the use of a cover codend to retain the fraction of escaping fish due to the use of the grid, allow to verify the jumbo squid escape. The results allow concluding that the use of this device has shown to be effective allowing the escape rate of non-target species catch, as well to posterior discards of these species.