By Catch: Seabirds, Sea mammals, Sea turtles and Sharks of Río de la Plata and its Maritime Front

DOMINGO A, P BORDINO, M FAVERO, R FORSELLEDO, S JIMÉNEZ, P MILLER, C PASSADORE & M PONS

Environmental Assessment and Planning of a Transboundary Fluvio-Marine Ecosystem: the Río de la Plata and its Maritime Front

Springer

Año: 2012;

A wide variety of seabirds, turtles and marine mammals and sharks (comprehensively including sharks, batoids and chimeras), likely to be incidentally captured in various fisheries, can be found in the Rio de la Plata and its Maritime Front (RPMF) (Chapter 9, 10 y 17, Domingo et al. 2006a, Domingo et al. 2007a, Domingo et al. 2008, Favero and Gandini 2008, Anónimo 2009, Passadore 2010). These four taxa comprise top predators whose role in the ecosystem is of great importance, and the removal of a portion of their populations may affect many other species (Chapter 10, Camhi et al.1998, Myers et al. 2007, Zhou et al. 2010). The taxa dealt with in this chapter share some life history traits (see Chapter 10) that render them vulnerable to a population decline, even with low levels of additional mortality in association to fisheries. Bycatch has proven to be one of the main causes of at sea mortality, thus causing the decline of a significant number of populations (Robertson and Gales 1998; Spotila et al. 2000; Fowler et al. 2005; Dulvy et al. 2008). The terms “bycatch mortality” (BcF) and “bycatch” (Bc) are often associated but it is necessary to distinguish clearly one concept from the other as the BcF/Bc ratio, which measures the impact level of bycatch, largely varies depending on the taxa and fisheries considered