Assessing interacting impacts of artisanal and recreational fisheries in a small Marine Protected Area (Portofino, NW Mediterranean Sea)

Riccardo Cattaneo‐Vietti,Celine Barrier,Luisa Mangialajo,Valentina Cappanera,Giulia Prato,Vasiliki Markantonatou,Didier Gascuel,Paolo Guidetti,Patrice Francour

doi:10.1002/ecs2.1601

Abstract

AbstractMarine Protected Areas (MPAs) have spread across the Mediterranean to protect its rich biodiversity and manage human activities for a more sustainable coastal development. Within MPAs, traditional artisanal fishing is competing for space and resources with increasing recreational fishing, likely leading to interacting ecological effects. Such effects are difficult to unravel, given the multispecies character of both fisheries and the complexity of the food webs upon which they both impact. To address these issues, we developed an Ecopath and EcoTroph trophic model for the Portofino MPA case study (NW Mediterranean), in particular to (1) identify keystone species and assess fishing impact on them; (2) analyze the interacting impact of artisanal and recreational fishing on ecosystem biomass and trophic structure; and (3) assess the impact of recreational fishing on artisanal fishing catches. Two high trophic level predator (HTLP) groups coupled important keystone roles with high sensitivity to fishing pressure and should thus be regarded as “sentinels” to be prioritized for the definition of management actions. Recreational fishing had the widest impact on the food web, strongly impacting HTLP. Simulation of different mortality scenarios for each fishery highlighted that the ecosystem is far from its carrying capacity for HTLP. Forbidding recreational fishing allowed a 24% increase in HTLP biomass and benefited artisanal fishing by increased availability of HTLP catches. Artisanal fishing alone could instead be maintained with a moderate impact on the food web. Overall, Ecopath and EcoTroph modeling is a valuable tool to advise MPA management, but it is essential to increase data availability and quality by developing long‐term monitoring programs on key species and on artisanal and recreational fishing.

Highlights

In the last decade, the ecosystem-based management approach has become the major call of action in the marine research context
We focused on the Portofino Marine Protected Areas (MPAs) (Ligurian Sea)
Biomass estimates were available for 60% of the groups, while the remaining 40% were estimated by the model (Table 1)

Summary

Introduction

The ecosystem-based management approach has become the major call of action in the marine research context. Artisanal fisheries are highly multi-specific (Farrugio et al 1993) and multi-metier, using a broad range of gears and techniques selected according to seasonal availability of target species (the concept of “metier” denotes a combination of fishing gear, target species, area, and season; Mesnil and Shepherd 1990, Biseau 1998) Such activity has long played a fundamental role in both the economy and society (Farrugio et al 1993) of the Mediterranean, with considerable cultural and historical significance, but is declining in many areas with a downward trend in the number of vessels and licenses, catches, and net revenues (Gomez et al 2006, Guyader et al 2013, Lloret and Font 2013, Di Franco et al 2014)

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Conclusion