Did the epibenthic bycatch at the Patagonian scallop assemblage change after ten years of fishing?

SCHEJTER LAURA; BREMEC CLAUDIA

Halifax, Canada

Workshop; 16th. International Pectinid Workshop; 2007

The aim of this study was to assess the composition and richness of benthic assemblages in the main Patagonian scallop areas subjected to fishing along the shelf break front of the Argentine sea, between the baseline condition in 1995 (without fishing) to 2006, considering the information of the exploration and monitoring cruises carried out by the INIDEP during 1995, 1997, 1998, 2001, 2002, 2003, 2004, 2005 and 2006.  In general terms, echinoderms were always dominant in by-catch groups. A total of 130 taxa was registered in the whole studied area, including strictly epibiont species, hydroids and sponges. Differences in richness during the study period were mainly due to differences in sampling effort (that was higher in the last two years) and to the expertise acquired in the identification of the taxa recorded. It is important to notice that taxa recorded during the baseline condition (pre-fishery) were always present during the last years of the study period. No loss of species was detected; only rare or occasional species were recorded sporadically. Considering MDS analysis, differentiation of northern and southern management units is noticeable, in all years, and also a differentiation between more distant beds. This differentiation is due to the different proportions of taxa biomass rather than differences in species composition. A reduced number of species greatly contributed to the establishment of the assemblages that, in general terms, were persistent in time and in the different study areas.