Ecosystem effects of fishing in the Mediterranean:
An analysis of the major threats of fishing gear and practices to biodiversity and marine habitats by
Sergi Tudela, Ph. D.
for FAO Fisheries Department (EP/INT/759/GEF) Vialle delle Terme di Caracalla 00100 - Rome, Italy
Contents Foreword 1. The impact of fishing on vulnerable groups and habitats 1.1. The impact of fishing on chondrichthyans 1.2. The impact of fishing on seabirds 1.3. The impact of fishing on turtles 1.4. The impact of fishing on Mediterranean monk seal populations 1.5. The impact of fishing on cetacean populations 1.6. The impact of fishing on seagrass beds 1.7. The impact of fishing on the seabed (soft and hard bottoms) and its associated benthic communities 2. Gears and fleets of special interest with respect to fishing impacts in Mediterranean waters 2.1. The ecosystem impact of bottom trawling 2.2. The impact of longlining on large pelagic populations 2.3. The ecosystem impact of artisanal gears 2.4. The case of Mediterranean driftnet fisheries 3. General discussion and conclusions: the ecosystem effects of fishing in the Mediterranean and their remedy from a systemic perspective References
i ii 1 1 5 8 12 15 21 23 26 26 29 31 34 35 38
About this document This document is intended as a contribution to the strategic action plans to limit the impact of fishing activities on biological diversity in the Mediterranean under the Strategic Action Plan for Biodiversity (SAP Biodiversity), which is expected to provide a logical basis for the implementation of the 1995 Specially Protected Areas Protocol (Barcelona Convention). The work has been structured around a set of self-contained sections dealing with the main threats to marine biodiversity (including both vulnerable species and habitats) arising from fishing gears or practices in use in Mediterranean waters. The issues have been dealt with in two sections, one on fishing impacts on vulnerable species and habitats, and the other on specific aspects related to selected fishing gears and practices of special interest in the Mediterranean. General single-species issues related to the overfishing of commercial species have been deliberately omitted from the analysis, since they are the object of extensive studies elsewhere and a great deal of attention is paid to them in other fora. The author has prepared an apparently classic analysis, useful for practical purposes, but tried to avoid the pitfall of a purely reductionistic dissecting of reality, aware of transversal or even higher-level issues connecting many of the individual questions analysed. An attempt has been made to give due weight to these interrelations as well as the overall ecosystem effects of fishing on the structure or functioning of the ecosystems (resulting from both past and present practices) throughout the different sections of this document. The document's chief merit is that it collates reliable information from different sources on the different ecosystem effects of fishing in the Mediterranean, and provides a coherent picture of the overall impact of fishing on regional biodiversity. Most of this integrative vision is specifically addressed in the conclusion section. This work is focused on the Mediterranean, discarding unnecessary or redundant information from other areas of the world, even if better studied. Where information related to some of the major issues is scarce, special attention has been devoted to the few studies available, given their qualitative importance. The aim has been, thus, to produce a specifically Mediterranean document. Acknowledgements The author is indebted to many people who have kindly contributed to this article with documents or any other kind of valuable information, as well as, simply, sharing their points of view on different aspects. Especial thanks are given to: Juan Antonio Camiñas, Instituto Español de Oceanografía (Spain);...
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