The bottom trawling is the word most used fishing art generating large amounts of discards and incidental captures with a wide variety of species. In the San Jorge Gulf Argentine Patagonia, operates a fleet whose target specie is the hake Merluccius hubbsi, alternating with red shrimp Pleoticus muelleri. The information for this study covers a period of 10 years (2003-2012) and was collected by the On-board Observer Program of the Chubut Province (POBCh). Were identified a total of 90 taxa, 33 invertebrates, 34 osteichthyes and 22 chondrichthyes. Multivariate analysis indicated differences in the composition of the catch when the target species was shrimp or hake. When the target species was the hake catch composition varied by fishing areas, this pattern was not observed when the target species was the shrimp, with different numbers of taxa in the northern and central Gulf (north: hake 79 taxa, shrimp 71, center: hake 60 taxa, shrimp 50). The utilization of different species caught when the fleet operated on hake was integral, however when the fleet operated on shrimp most of the taxa were discarded. This study characterized the composition of the fleet catches at San Jorge Gulf, described the species caught when the fleet operates on hake or shrimp, analyzes the frequency of occurrence and abundance and describes the use of different taxa identified.

Bottom trawl fishing is the most used worldwide gear generating large amounts of discards due to bycatch of a variety of species. Shrimp fisheries are recognized for their high incidence in global discards. In waters of Patagonia Argentina (43°S - 47°S) an industrial shrimp fishery of high economic value is developed whose target species is the Patagonian shrimp Pleoticus muelleri. The information presented in this study comprises a period of 12 years (2003-2014) and it was gathered by the On-board Observer Program. The Program collects information of all species captured in the fishing fleets. The data analyzed corresponds to the double-rigged otter trawler fleet and the coastal fleet. The fish bycatch composition was characterized in both fleets and the frequencies of occurrence of species and the assemblage areas were analyzed. A total of 101 fish species were identified (59 families) of which 69 were bony fishes, 29 cartilaginous fishes and three species of jawless fishes. The assemblages described correspond to coastal and deep waters, and they are integrated by temperate and subtropical species pointing out the area as an ecotonal zone.