The effect of the use of fish by-catch reduction devices and the retention of marketable non-targeted fish on the reduction of seabird abundance and interaction with commercial trawlers

JUAN PABLO SECO PON; MARCO FAVERO

Conferencia; 5th International Albatross and Petrel Conference; 2012

It is known that reducing foraging opportunities to seabirds attending vessels by reducing discards decrease seabird attendance at trawl vessels, and consequently, may reduce interactions. To date, investigations into discard management have focused on the effects of holding discards in the form of fishery waste for specific periods and differences in the form of discharged waste. For some vessels currently operating in Argentina deepwater commercial ice trawl fleet, there are limited options for managing fish by-catch on board, though, it is mandatory for vessels to use fish by-catch reduction devices (FBRDs) in nets. We assessed the effect of FBRDs and retention of marketable non-targeted fish in reducing seabird abundance and interaction with ice trawlers operating in Argentina. The abundance of seabirds – particularly albatrosses and petrels – attending vessels and the number of interactions (i.e. contacts) with fishing gear were recorded during normal operations, covering 63 fishing days, 177 h of observations and 175 trawls. Samplings were conducted aboard two trawlers between spring 2009 and spring 2011 under different scenarios of use/no use of FBRD and retention of non-targeted marketable fish. The seabird abundance under operations using FBRD was significantly lower than those without FBRD. Further, seabird interactions were significantly lower in the net equipped with a FBRD compared to those analogous values in the no-FBRD net under conditions when the trawler retained non-targeted fish. We observed significant differences in seabird abundance under scenarios of use/no use of FBRD, but also in contacts with fishing gear under scenarios of non-target fish retention. The observed differences between seabird abundances were not symmetrical to the observed interaction rate, thus, bringing uncertainties about the use of seabird abundance as a proxy of risk for seabirds.