Invertebrate bycatch in Patagonian scallop fishing grounds: a study case with data obtained by the On Board Observers Program

MARIANA ESCOLAR; MARIANO DIEZ; DANIEL HERNÁNDEZ; ANGEL MARECOS; SILVANA CAMPODÓNICO; CLAUDIA BREMEC

REVISTA DE BIOLOGIA MARINA Y OCEANOGRAFIA

INST OCEANOLOGIA

Año: 2009 vol. 44 p. 369 - 377

0717-3326

Since the beginning of the Patagonian scallopfishery Zygochlamys patagonica, in the Argentine Sea in 1996,an On-Board Observers Program (OBOP) was established atthe National Institute of Fishery Research and Development(INIDEP). The general trends of the bycatch composition andbiomass were analysed from information on catches and fishingeffort (219 trips, 575 samples), collected in five scallop bedsbetween 39º and 44º S during the period 1997-2002, providedby the OBOP. Large variations in average density of bycatchand the presence of eight taxonomic groups were determinedduring the study period. Echinodermata was the dominant taxonin most of the scallop beds. Echinoderms and gastropods showedan increase in biomass and sessile organisms were scarce in theSWSAO bed, subjected to high and continuous fishing effort.In the SWTB bed, with the lowest fishing effort, sessileorganisms showed a decrease during the study period, while novariations occurred in the case of echinoderms and gastropods.The mentioned groups, mainly scavengers and predators, wouldbe favoured by fishing activity that increased food availability(discards and damaged organisms). Contrarily, potentialsettlement substrates as sessile organisms, decreased in areaswith intensive fishing activities. We stress out the validity ofthis source of data, which widens the spatio-temporal coverageof the yearly stock assessment cruises and is optimal forproducing long-term databases.