Trends in the exploitation of South Atlantic shark populations
Published online on 04. December 2015
Trends in the exploitation of South Atlantic shark populations
Rodrigo Barreto, Francesco Ferretti, Joanna Mills, Alberto Amorim, Humber Andrade, Boris Worm, Rosangela Lessa
ABSTRACT:
Approximately 25% of globally reported shark catches occur in Atlantic pelagic longline fisheries. Strong declines in shark populations have been detected in the North Atlantic while in the South Atlantic the situation is less clear, although fishing effort has been increasing in this region over the last 50 years. Here we provide a synthesis of information on shark catch rates (based on 871,177 sharks caught on 86,492 longline sets) for the major species caught by multiple fleets in the South Atlantic between 1979 and 2011. Three distinct phases in these data are identified: a first phase, characterized by a few fleets mainly fishing for tunas; a second phase, where many fleets were fishing for tunas, swordfishes and sharks; and a third phase, where fewer fleets were fishing for multiple species and restrictive measures were being implemented. Generalized linear models were used to standardize catch rates and identify trends in each of these phases. Shark catch rates increased in the first phase, when fishing effort was low, then decreased in the second phase, when fishing effort was rapidly expanding, and remained stable in the third phase, when fishing effort was again low. Our results indicate that most shark populations in the South Atlantic are currently depleted, but can recover where fishing effort is reduced accordingly. In this context, it is of concern that comprehensive data collection and management of these fisheries has ceased.
Conservation Biology, Accepted Article, doi: 10.1111/cobi.12663