-Several fleets with various fishing strategies operate as a mixed fishery in the Bay of Biscay. Among the main fleets, bottom trawlers target Norway lobster (Nephrops norvegicus) and, together with gillnetters, they also catch hake (Merluccius merluccius). Trawling leads to average-size catches that are below the minimum landing size (MLS); such catches are discarded since they cannot be sold. These discards result in negative impacts on stock renewal, as most of them do not survive. This also results in an economic loss for both bottom trawlers and gillnetters since these discards represent a future loss of rent. This study, based on the 2009 and 2010 selectivity experiments at sea, assesses the short-and long-term bio-economic impacts of four experimental selective devices aimed at reducing N. norvegicus and M. merluccius discards over a 20-year simulation period. Tests were conducted at sea on a research trawler. Using the impact assessment model for fisheries management (IAM model), selectivity scenarios for trawlers in the Bay of Biscay were compared to a theoretical selective scenario of adopting an optimal device that catches only N. norvegicus and M. merluccius above MLS (9 cm and 27 cm total length, respectively). Costs and benefits were analyzed with the objective of finding the best compromise between a reduction in discards of undersized fish and a loss of valuable catches among the experimental devices. Selectivity scenarios show positive impacts on stocks but different economic impacts between fleets. The combination of a square mesh cylinder with a grid and square mesh panels gives the closest results to the theoretical scenario tested in terms of stock recovery and economic benefits. This experimental device leads to low economic losses in the short term and eventually to higher N. norvegicus yields, which would be favourable for fleets that greatly contribute to N. norvegicus fishing efforts.
In the context of the Common Fisheries Policy Reform, the implementation of multiannual management plans for fisheries and the annual quota negotiations between EU member states has generated a growing demand from stakeholders and managers for integrated advice that goes beyond the usual biological advice. This has led to the emergence of bio-economic tools and methods for the comparison of the biological, economic and social tradeoffs associated with alternative options for fisheries management. A Decision Support Framework (DSF) has been developed in this context, with the objective to tackle technical and methodological challenges to be able to provide bio-economic advices to support decision at national and European level. It is based on a partnership approach involving the fishing industry, managers and scientists and on technical protocols. We present the development of a partnership DSF within three local case studies, highlighting key challenges and lessons learnt regarding appropriateness and application of a DSF. The data processing methods and collaborative platform were pivotal for scoping out objectives and management options, and for aligning DSF outcomes with decision makers' needs and agendas. Definition of common standards and institutionalization of the use of partnership DSF are still required to operationalize the integrated advice process at national and European levels.
Abstract. An individual-based bio-economic model (IAM) is presented and applied to the Bay of 7Biscay sole fishery to investigate alternative quota management systems from a multi-criteria 8 perspective. For this study, the model integrates several institutional arrangements related to catch 9share management. The current French co-management system with non-transferability of quota is 10 compared to an alternative ITQ system in a context of transition to maximum sustainable yield 11 (MSY). Trade-offs between ecological and socio-economic impacts are highlighted and the 12 effectiveness of governance scenarios is discussed in regard to the challenge of capacity adjustment. 13
Well-established single-species approaches are not adapted to the management of mixed fisheries where multiple species are simultaneously caught in unselective fishing operations. In particular, ignoring joint production when setting total allowable catches (TACs) for individual species is likely to lead to over-quota discards or, when discards are not allowed, to lost fishing opportunities. Furthermore, economic and social objectives have been poorly addressed in the design of fisheries harvest strategies, despite being an explicit objective of ecosystem-based fisheries management in many jurisdictions worldwide. We introduce the notion of operating space as the ensemble of reachable, single-species fishing mortality targets, given joint production in a mixed fishery. We then use the concept of eco-viability to identify TAC combinations which simultaneously account for multiple objectives. The approach is applied to the joint management of hake and sole fishing in the Bay of Biscay, also accounting for catches of Norway lobster, European seabass and anglerfish. Results show that fishing at the upper end of the MSY range for sole and slightly above Fmsy for hake can generate gains in terms of long-term economic viability of the fleets without impeding the biological viability of the stocks, nor the incentives for crews to remain in the fishery. We also identify reachable fishing mortality targets in the MSY ranges for these two species, given existing technical interactions. Keywords Eco-viability • Mixed fisheries management • Bio-economic modelling • Integrated TAC advice 1 Introduction Ecosystem-based approaches are increasingly being adopted for the management of natural resources, and fisheries make no exception, with the proposal of ecosystem-based fisheries management (EBFM) guidelines in the early 2000s [1, 2], and their subsequent implementation in policy [3, 4]. Among other aspirations, EBFM aims at accounting for the technical interactions among jointly caught species Electronic supplementary material The online version of this article (
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