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Marine Ecology Progress Series

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MEPS 603:13-27 (2018)  -  DOI:

Dolphin predation pressure on pelagic and demersal fish in the northwestern Mediterranean Sea

Quentin Queiros1,*, Jean-Marc Fromentin1, Guillelme Astruc2, Robert Klaus Bauer1, Claire Saraux1

1MARBEC, Univ Montpellier, CNRS, Ifremer, IRD, 34200 Sète, France
2CEFE, CNRS, Univ Montpellier, Univ Paul Valery Montpellier 3, EPHE, IRD, 34293 Montpellier, France
*Corresponding author:

ABSTRACT: Sardine Sardina pilchardus, anchovy Engraulis encrasicolus and European hake Merluccius merluccius represent a significant part of the commercial landings in the Gulf of Lions (northwestern Mediterranean Sea). However, their stocks have shown severe declines during the last decades due to fishing pressure and/or environmental changes. The aim of this study was to estimate the current predation pressure of bottlenose dolphins Tursiops truncatus and striped dolphins Stenella coeruleoalba—which are abundant in the area—on sardine, anchovy and hake. To do so, we developed an original approach based on several data sets and models (aerial surveys, stomach contents, allometric and stock assessment models) and Monte Carlo simulations to incorporate various sources of uncertainty due to data limitations. Despite the uncertainties, the results showed that dolphin predation pressure on sardine and anchovy was extremely low in the Gulf of Lions (all simulations <0.5% of the available stock), indicating little impact of dolphins on those populations. However, significant predation pressure on hake (median value: 23%) was detected, a value which might have doubled in the last 30 yr because of hake overfishing. Overexploitation has thus reinforced the natural mortality of hake due to dolphin predation, but this predation pressure remains 2 to 3 times lower than that exerted by fisheries.

KEY WORDS:Predation pressure · Top-down effect · Bottlenose dolphin · Striped dolphin · European hake · Sardine · Anchovy · Gulf of Lions

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Cite this article as: Queiros Q, Fromentin JM, Astruc G, Bauer RK, Saraux C (2018) Dolphin predation pressure on pelagic and demersal fish in the northwestern Mediterranean Sea. Mar Ecol Prog Ser 603:13-27.

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