From Trawl to Pots, a Bio-economic Analysis of Gear Changement

Poor selective gears like bottom trawlers are known to induce joint productions ie catch of several categories of fish by targeting one category in particular. Joint productions can be inter-species or intra-species. They can be retained to be sold or discarded most of the time with high mortality rates when caught by trawlers. Joint productions make management more complicated as they make classical solutions known to reduce or negate the effects of negative externalities difficult to apply. In this paper, the bio-economic impact of changing gear to reduce joint productions and so limit the external effects is studied in the case of the Nephrops trawl fishery in the bay of Biscay. The example of the Nephrops pot fishery of Loch Torridon (Scotland) compared to the Nephrops trawl fishery in the bay of Biscay enables to discuss the exploitation conditions leading to the success of an alternative gear. An alternative Nephrops pot métier for the Nephrops trawler fleet is parameterized and the bio-economic implications of a gear changement are analyzed in the case of a normative trawl interdiction and under several economic regulations inciting to gear changement.Keywords: Nephrops norvegicus, Trawl selectivity, Fisheries management, Bio-economic analysis, Gear changement, Cost-benefit analysis, Loch Torridon, Scotland, Bottom trawlers, Fisheries Economics, Bay of Bisca

"La Grande Vasière" mid-shelf mud belt : Holocene sedimentary structure, natural and anthropogenic impacts

The Quaternary sequence of the Armorican continental shelf in the Bay of Biscay is setting down above one regional erosion surface, which has been produced by successive transgressions that occurred during the last deglaciations. The few meters of the sequence covers the Holocene period and it is composed by two clean and sandy units at the base followed by thin (few decimetres) clayed sand unit and mud (few millimetres) unit in the top. The two upper units form the improperly called "La Grande Vasière" area over 8,000 km2. The settlement of these sedimentary units occurred since 8,000 C14 years BP, previously to other coastal mud fields setting of the shelf. Historical grain size data show that the mud field has lost part of the fine content during the last 30 years. "La Grande Vasière" evolves at the rhythm of the cycles of deposition and remobilization. Fluvial supplies and tide currents are the major control factors of the deposition. Bioturbation enhances the homogenization of the surficial sediments. Waves and anthropogenic actions are the main factors for the remobilization of the fine particles. The action of both the storms and the bottom trawls are tentatively quantified

A Fish Discarding Model Including Sorting Behaviour

This paper proposes a formal analysis of the discarding issue including the sorting labour costs. Empirical evidences from an application to the Nephrops fishery in the Bay of Biscay show that sorting is an important time consuming activity on board and a factor of discarding. However existing literature does not explicitly take into account the sorting activity and mainly focus on quota and catch constraints. The discarding model described in the paper includes sorting as a factor explaining discards. The costs of sorting landings and the time to sort them are included in the approach. The model is developed for one species studied at a tow scale with the assumption that catches are exogenous. It is shown that taking sorting costs into account, discarding of one species may occur and that time or effort constraints can induce an over incentive to discard

A Stochastic Viability Approach for Ecosystem-Based Management of Mixed Fisheries: The Case of The Bay of Biscay Demersal Fisheries

Marine scientists and stakeholders are increasingly advocating ecosystembased fishery management (EBFM). However, the way to operationalize such EBFM remains controversial. The viability approach can be a relevant modelling framework for EBFM as it accounts for dynamic complexities, uncertainties, risks and sustainability objectives balancing ecological, economic and social dimensions together with intergenerational equity. Mixed fisheries operating in the Bay of Biscay provide a challenging example to illustrate these issues. The present paper focuses on the case of the demersal fisheries catching nephrops, hake, sole and monkfish. A bioeconomic multi-species and multi-fleets model is developed to examine the capacity for the stochastic viability framework to assist in developing practical approaches to EBFM. The model integrates the dynamics of the harvested stocks with an uncertain recruitment and technical interactions through joint catches. It relies on data from ICES and IFREMER. A coviability analysis of the fish populations/fisheries system is performed to investigate how to simultaneously preserve the species (using Bpa precautionary referenced points) and guarantee economic incomes for the fleets. First results suggest that the viable harvesting intensities require a significant reduction in the effort of some fleets, as compared to reference year 2006.Keywords: Bioeconomic Analysis of Fisheries, Fish and Aquaculture Sectors Development, Fisheries EconomicsKeywords: Bioeconomic Analysis of Fisheries, Fish and Aquaculture Sectors Development, Fisheries Economic

Mediterranean Fishing Strategies and interactions Between Small Scale Fisheries and Trawlers in the Mediterranean Hake Fishery

Mediterranean fisheries are characterized by a high diversity of fishing strategies that can be differentiated according to a gradient from the coast to the offshore area. Over the gradient, fleets interact through the resource. The paper first provides a description of the fishing strategies and proposes a typology for the French Mediterranean fleet based on this gradient. A focus on the interactions between fleets is then provided through the example of the Mediterranean hake fishery. In this fishery, two main strategies, small scale gillnetters operating in the 3 milles area and trawlers operating more offshore, compete for the resource. A description of these two segments is provided and the management implications of the technical interactions are highlighted.Keywords: Fisheries Economics, Fish and Aquaculture Sectors Development, Small Scale FisheriesKeywords: Fisheries Economics, Fish and Aquaculture Sectors Development, Small Scale Fisherie

Investigating tradeoffs in alternative catch share systems with a vessel-based bio-economic model

A vessel-based bio-economic model (IAM) is presented and applied to the Bay of Biscay sole fishery to investigate alternative quota management systems from a multi-criteria perspective. For this study, the model integrates several institutional arrangements related to catch share management. The current French co-management system with non-transferability of quota is compared to an alternative ITQ system in a context of transition to maximum sustainable yield (MSY). Trade-offs between ecological and socio-economic impacts are highlighted and the effectiveness of governance scenarios is discussed in regard to the challenge of capacity adjustment. Results emphasize that the introduction of ITQ is expected to reduce by 40% the number of vessels in the fishery. While effectively mitigating the economic impacts of the transition phase to MSY, ITQs are also expected to significantly increase the fishing effort by trawlers, which may cause ecological concerns. The scenarios tested also include the simulation of a decommissioning scheme where subsequent decommissioned vessels are significantly different from the vessels that would lease out their quotas in an ITQ system, resulting in differentiated ecological and socio-economic impacts between scenarios

Estimating MSY and MEY in Multi-Species and Multi-Fleet Fisheries: The Case of the Bay of Biscay Mixed Fisheries

Most fish stocks worldwide are not optimally exploited and are therefore are producing less in biologic and economic terms that what it could be obtained. MSY objective for all the stocks by 2015 is put forward by several countries as management target to be achieved, while other countries such as Australia have moved towards MEY as target. In multi-species and multi-fleet fisheries however single species assessments and MSY and MEY reference points are often not valid. In this paper, we analyze the calculation of MSY and MEY in multi-species and multi-fleet fisheries, applied to the Bay of Biscay demersal fisheries. Estimations of MSY and MEY performed in this paper show that increases of the overall landings and economic performances can be obtained by fishing effort reductions and global selectivity improvements in the Bay of Biscay demersal fishery. In this paper we have also shown the importance of accounting for the multi-fleet nature of the fisheries, and so the capacity to allocate fishing effort between fleets to obtain better yields taking into account joint production processes, various métiers and reallocation of effort (both in production and economic terms). Estimating profitability changes when fishing at MEY and in the current situation of overcapacity and overexploitation offers an estimation of the costs of not fishing at MSY and MEY

A multidisciplinary approach to the spatial dimension in ecosystem-based fisheries management

This study considers how to reconcile different spatial scales to find the best common denominator to be used as an ecosystem-based management unit. For this, two fishery production zones differing ecologically, economically, legally and institutionally were investigated. The first case study is located within French territorial waters, in a MPA created in 2007- the Parc Naturel Marin d'Iroise (PNMI). The second case study, the Bay of Biscay, covers both territorial waters and the French exclusive economic zone. The paper adopts a multidisciplinary approach. Relevant questions concern how marine space is shared between exploited species and fishing fleets, especially the spatial mobility strategies they employ. An assessment of the institutional system established for the PNMI contributes to the discussion of changes in coastal space use. It is obvious that the area in need of protection, defined on the basis of essential fish habitats, does not solely concern the fisheries located within the coastal zone. Experiments conducted by scientists and professionals in the Bay of Biscay provide other key points for the discussion in terms of what institutional frameworks to promote

Addressing the Distribution of Bio-Economic Impacts of Management Measures Between Fleets: the Case of the Demersal Fisheries in the Bay of Biscay

Assessing distribution of the expected bio-economic impacts of management measures between fleet segments is a main issue for decision making in fisheries management. This requires as a first step a good description of the system and of the interactions between fleets through stocks. Making this assessment operational also needs flexible and fast capabilities to mobilize appropriate data to perform the impact analysis. Bio-economic modelling of the system allows performing simulations of management scenarios and to analyze expected costs and benefits at short, middle and long terms. The paper addresses the question of differentiated impacts on fleets in the case of the demersal fisheries in the bay of Biscay. As mixed fisheries, they are characterized by high technical interactions mainly derived from targeting or by-catching hake, Nephrops, anglerfish or sole and are relevant illustrations to address this question. The fleets involved in the Nephrops, hake, sole and anglerfish fisheries in the bay of Biscay are first characterized in terms of contributions to fishing mortality of these species and gross revenue dependence and their activity, productions and economic profitability are described. The paper then analyzes the impacts of effort and selectivity measures for these fleets through a multi-fleets, multi-metiers, multi-species bio-economic model. Methodological issues are underlined for operational bio-economic modelling and management plan assessment.Keywords: Fisheries Economics, Bioeconomic Analysis of Fisheries, Fish and Aquaculture Sectors Developmen

Mutational analysis of the PLCE1 gene in steroid-resistant nephrotic syndrome

International audienceBackground: Mutations in the PLCE1 gene encoding phospholipase C epsilon 1 (PLCε1) have been recently described in patients with early-onset nephrotic syndrome (NS) and diffuse mesangial sclerosis (DMS). In addition, two cases of PLCE1 mutations associated with focal segmental glomerulosclerosis (FSGS) and later NS onset have been reported. Methods: In order to better assess the spectrum of phenotypes associated with PLCE1 mutations, we performed mutational analysis in a worldwide cohort of 139 patients (95 familial cases belonging to 68 families and 44 sporadic cases) with steroid-resistant NS presenting at a median age of 23.0 months (range 0-373). Results: We identified homozygous or compound heterozygous mutations in 33% (8/24) of DMS cases. PLCE1 mutations were found in 8% (6/78) of FSGS cases without NPHS2 mutations. Nine were novel mutations. No clear genotype-phenotype correlation was observed, with either truncating or missense mutations detected in both DMS and FSGS, and leading to a similar renal evolution. Surprisingly, 3 unaffected and unrelated individuals were also found to carry the homozygous mutations identified in their respective families. Conclusion: PLCE1 is a major gene of DMS and is mutated in a non-negligible proportion of FSGS cases without NPHS2 mutations. Although we did not identify additional variants in 19 candidate genes (16 other PLC genes, BRAF, IQGAP1 and NPHS1), we speculate that other modifier genes or environmental factors may play a role in the renal phenotype variability observed in individuals bearing PLCE1 mutations. This observation needs to be considered in the genetic counselling offered to patients