Suchergebnisse

5 pages, 1 figure, 7 tables ; The formation of ex-vessel price of two important Mediterranean fisheries products (hake and red shrimp) was studied through an inverse demand approach, using data from the Catalonia bottom trawl fishery (NW Mediterranean). In both species, the landings by commercial category (proxy for fish size) and total landings determined the daily price fetched at the auction, as summarized by the quantity and scale coefficients ("flexibilities") derived from the inverse demand model. In general, quantity flexibilities were between −0.1 and − 0.6, indicating that a 1% increase in the landings of one category (for a given species) would reduce the average daily ex-vessel price by 0.1–0.6%. Scale flexibilities were generally lower than − 1, showing that these species tend to behave non-homothetically, especially for the large size categories. These results imply that changes to the quantities landed and the size composition of landings, resulting for instance from fisheries management measures, will affect sale prices. Simulations of sale price for scenarios of reduced landings, in line with fishing at maximum sustainable levels, showed that losses in revenue would be much less than the losses projected with constant prices. Similarly, higher landings resulting from rebuilt stocks would yield lower revenues from these stocks because of the generally negative flexibilities ; The European Union H2020 research programme contributed funds to this research through contract grant nº 773713 (project Pandora) ; With the institutional support of the 'Severo Ochoa Centre of Excellence' accreditation (CEX2019-000928-S) ; Peer reviewed

9 pages, 5 figures, 3 tables, 1 appendix ; The exploitation of mixed fisheries leads to trade-offs between fisheries rent, production (landings) and resource conservation because harvest rent cannot be optimized simultaneously for all species. Additionally, the exploitation of mixed fisheries by heterogeneous fleets complicates their management because of the necessity to allocate catch or effort quotas, under some criterion of efficiency or equitability. The allocation of fishing opportunities impacts directly on the availability of jobs in fisheries. To analyse the trade-offs between employment and profits in mixed fisheries, an optimization bioeconomic model was built for the three bottom-trawl fleet segments operating in the Catalonia demersal fishery (NW Mediterranean Sea). The fishery is subject to a multiannual management plan to align fishing effort with the fisheries mortality that would produce the maximum sustainable yield. The optimal effort allocation among the three fleet segments were compared subject to alternative fisheries management policies: (i) maximum sustainable yield, (ii) maximum economic yield, (iii) maximum labour remuneration, (iv) pretty good yield, and (v) equilibrium biomass larger than biomass at maximum sustainable yield, taking into account the multispecies nature of the fishery. The results show that all management policies provide higher profits than current. In the first three scenarios, high profitability can be made compatible with a lower number of better paid jobs, because the optimal allocation of effort in most scenarios would imply a reduction in the number of vessels. The results also show that the current number of vessels and effort distribution (which are the result of a historical process, rather than the results of a management strategy) are far from any optimum ; The European Union H2020 research programme contributed funds to this research through contract grant n 773713 (project Pandora). With funding from the Spanish government through the 'Severo Ochoa Centre of Excellence' accreditation (CEX2019-000928-S) ; Peer reviewed

7 pages, 2 figures, 4 tables ; The viability of Mediterranean marine fisheries is increasingly under threat due to the low biological productivity of overexploited stocks, low economic performance of the fishing units, and offer of unattractive jobs, among other. This has resulted in a decrease of 30% in the number of fishing units active in European Union Mediterranean fisheries over the period 1995–2016. The detailed causes for this decline are investigated here based on an analysis of the entry/exit dynamics of the entire fleet having operated in Catalonia (NW Mediterranean) as a case study. The decision made by owner-operators, in terms of entering, remaining or exiting the fishery, of 1195 fishing units in the period 2000–2018 was analysed. The results show that fishing vessels have a high probability (95%) of remaining in the fishery and very low probability of entering (<1%). The exit rate was estimated at 4.5% annually, resulting in a reduction of 42% of the fleet size over the study period, from 894 active vessels at the beginning of 2000 to 518 at the end of 2018. A statistical analysis of the factors conditioning the entry/exit dynamics by means of a multinomial choice model showed that the age of the vessel, the value of landings, the amount of decommission aid offered by the local fisheries management administration and a proxy variable for fuel costs were significant explanatory variables. The study concludes that the fleet is likely to continue to shrink, without immediate stock or ecosystem conservation benefits, unless bold steps to reformulate fisheries management in the Mediterranean are taken ; The European Union H2020 research programme contributed funds to this research through contract grant nº 773713 (project Pandora)

5 pages, 3 figures. ; Recent studies have shown that the population dynamics of deep-sea organisms are affected by coupling between surface oceanic processes and energy, or trophic resources, reaching the sea floor. I analysed the correlation between the landings of a deep-sea shrimp (Aristeus antennatus) in Catalonia (NW Mediterranean) and the climatic indices of the annual North Atlantic Oscillation (NAO) and winter NAO between 1971 and 2007. I show that the size of landings is significantly correlated with the NAO and with the winter NAO, with 2 and 3 yr lags in both cases. Considering that around 60% of the landings comprise 2 to 3 yr old females, my results suggest that climatic conditions over the western Mediterranean (especially in winter) influence the year-class strength of this deep-sea shrimp, fished from 600 to 800 m depth. ; I thank Mr. M. Sans, General Director of the Fisheries Directorate of the Catalonian Autonomous Government, for access to their fisheries landings database. ; Peer reviewed

12 pages, 3 figures, 4 tables, supplementary data https://doi.org/10.1016/j.jenvman.2021.112728 ; Fishing communities in the Mediterranean Sea face challenges in dealing with Common Fisheries Policy (CFP) ecosystem-based management measures aimed at reducing fishing effort and implementing partial closures of fisheries. The Participatory Action Research method is used here as a "pilot experience" to gather reactions from fishers, scientists and fisheries managers to the Western Mediterranean Multi-Annual Demersal Fisheries Plan (WM MAP) by identifying needs and concerns, but also alternatives to maintain the viability of the fishery. The data gathering process consisted on a structured questionnaire administered during a workshop to 40 stakeholders involved in Spanish fisheries in the Mediterranean, followed by an open discussion session. The results show that fishers disagree with the new regulations, which they perceive as yet another layer of restrictive regulations for an industry that faces major challenges and currently has low profitability, whereas scientists tended to agree more with the WM MAP than the administration or the fishers. Nevertheless, all stakeholders agree that the values of the cultural heritage of fisheries and the exploration of alternative marketing systems should balance the productivity-based approach to fisheries policies followed so far, that have shown signs of failure. According to stakeholder perceptions, this would improve the economic and social viability of fisheries, as well as highlight the value of fishing activity and its social prestige. Integrating the value of cultural heritage and post-production processes into the CFP would improve stakeholder involvement in fisheries policies. Through participatory research methods the ecosystem-based management approach could be embedded in a community-based approach, integrating its social actors in a proactive attitude and considering fisheries as a human activity socially and culturally rooted in the environment, which would enhance the effective implementation of fisheries policies ; The EU (Horizon 2020 programme) provided funding for this research through project "Paradigm for New Dynamic Ocean Resource Assessments and Exploitation" under the grant agreement 773713 ; With funding from the Spanish government through the 'Severo Ochoa Centre of Excellence' accreditation (CEX2019-000928-S) ; Peer reviewed

21 pages, 4 figures, 6 tables, supplementary information https://doi.org/10.1007/s11160-021-09681-9.-- Data availability statement: All the data used in the present study is contained in the online Supplementary information ; The distribution of hermaphroditism in fishes has traditionally been mainly explained by its dependence on biotic factors. However, correlates with major abiotic factors have not been investigated on a quantitative basis and at a global scale. Here, we determined the incidence of hermaphroditism in fish at the family and species level, tested the hypothesis that evolutionary relationships account for the poor presence of hermaphroditism in freshwater species, and tested the association of sexual systems with latitude, habitat type and depth. Functional hermaphroditism is reported in 8 orders, 34 families and 370 species of fishes, all teleosts. Sequential hermaphroditism predominates over simultaneous hermaphroditism at a ratio ~ 5:1 and protogyny (female-to-male sex change) predominates ~ 6:1 over protandry (male-to-female). We found 12 hermaphroditic species that can live in freshwater. However, seven of these species are from four primarily marine families while there are only five species from two mostly freshwater families. Protogynous and bi-directional sex changers have a tighter association with reef-associated tropical and subtropical habitats when compared to protandrous species, which tend to be more plastic in terms of distribution requirements. Finally, simultaneous hermaphrodite species live both in the deep sea and shallow waters in similar proportions. This study can be the basis for further research in specific groups for different purposes, including ecological and evolutionary issues as well as conservation and management of exploited species. Understanding the environmental correlates can help to forecast changes in the distribution or phenology of hermaphrodites in a global change scenario ; We also acknowledge the funding of the Spanish government through the 'Severo Ochoa Centre of Excellence' accreditation (CEX2019-000928-S) and grant PID2019-108888RB-I00. Open Access funding provided thanks to the CRUE-CSIC agreement with Springer Nature ; Peer reviewed

9 pages, 4 figures, 3 tables, supplementary data https://doi.org/10.1016/j.fishres.2020.105814 ; A multi-annual generalized depletion (MAGD) model was applied to the data-limited Mediterranean sandeel boat seine fishery in Catalonia. The results show that catch and effort data at high temporal frequency (month), complemented with biological information on mean body weight and initial estimates of natural mortality and time of recruitment to the fishery, can be used to produce assessment results of interest to fisheries management. The estimates of fishing mortality obtained for the Mediterranean sandeel in this fishery are very low compared to natural mortality estimates (less than 10 %) and the important fluctuations in recruitment strength suggest that the dynamics of this fishery are mainly driven by density-dependent effects on the population dynamics of the species. Given the high rate of natural mortality estimated (∼ M = 2 y), its short life-span (1–2 y) and that exploitation is based on age 0 individuals, it is recommended to keep exploitation rates at current levels (<4%), which can be adapted on a short time basis, subject to the perceived availability of the stock. This low exploitation rate is compatible with a precautionary escapement biomass of 40 %. A parallel stock assessment was carried out with a surplus production model (SPiCT), which led to similar trends in biomass and fishing mortality as the MAGD model application. The parameter estimates obtained with both models have wide confidence intervals, particularly for the quantities related to population size, suggesting that these data-limited models are likely to suffer from low precision. Precision was lower for SPiCT than for MAGD, and the performance diagnostics for SPiCT were poor. The MAGD model can be used for small-scale fisheries that are unlikely to meet the requirements of standard stock assessments based on catch-at-age methods and can provide indicators (fishing mortality, vulnerable biomass) of interest to fisheries managers ; The Fisheries Service of the Autonomous Government of Catalonia provided funding for this study. With the funding support of the 'Severo Ochoa Centre of Excellence' accreditation (CEX2019-000928-S), of the Spanish Research Agency (AEI)

11 pages, 7 figures, 4 tables ; [EN] We present a simulation bioeconomic model based on an age-structured population biological sub-model and an economic sub-model with vessel-specific dynamics, applied to two red shrimp (Aristeus antennatus) stocks in the NW Mediterranean. The model is dynamic, the economic sub-model is disaggregated at the level of vessel and the two sub-models are linked by means of a fishing mortality vector. We analyzed the projection of selected indicators (catches, overall profits, fishing mortality and spawning stock biomass) for the target species of the deep-water trawl fishery in the NW Mediterranean, red shrimp. We built three alternative management scenarios based on input control and we examined the performance of these management strategies against the current management policies. The three alternative management strategies were: i) increase the cost of effort by eliminating the fuel tax exemption currently in place, ii) limit the nominal effort level (days at sea) to current levels, in order to offset the increasing trend observed in the last decade, and iii) change the selectivity patterns of the trawl by increasing mesh size. Our results show that for the two stocks analyzed, any of the three management measures (input controls) would be beneficial both to the stock and the fleets (over the medium and long terms) when compared with the projections over time of the status quo. Improving the selectivity of the fishing gear is more beneficial than limiting nominal effort or increasing the cost of effort. Comparing the performance of the management strategies on two stocks, one heavily fished and the other moderately so, we show that none of these management measures is able to substantially redress the situation of a heavily fished stock, implying that for the full recovery of heavily fished red shrimp stocks, we need to contemplate even stricter measures of management. © EDP Sciences, IFREMER, IRD 2006 ; [FR] Nous présentons un modèle de simulation bioéconomique, basé sur un sous-modèle d'une population structurée en âge et d'un sous-modèle économique d'une flottille spécifique, appliqué à deux stocks de crevettes rouges ou « gambas » (Aristeus antennatus) du nord-ouest de la Méditerranée. Le modèle est dynamique, le sous-modèle économique est individualisé au niveau du chalutier, et les deux sous-modèles sont liés par l'intermédiaire de la mortalité par pêche. Nous analysons la projection des indicateurs sélectionnés (captures, profits, mortalité par pêche et biomasse du stock de géniteurs) pour ces crevettes, espèces-cibles de la pêche chalutière profonde du nord-ouest de la Méditerranée. Nous avons construit 3 scénarios possibles de gestion, basés sur le contrôle des gains et nous examinons leur performance par rapport aux politiques courantes de gestion. Les trois stratégies alternatives de gestion sont : 1) augmenter le coût de l'effort de pêche, en supprimant l'exemption de la taxe de gasoil, actuellement en vigueur ; 2) limiter le niveau d'effort nominal (nombre de jours de mer) dans le but de compenser la tendance à l'augmentation, observée depuis dix ans, et 3) changer la configuration de sélectivité du chalut, en augmentant la taille des mailles. Nos résultats montrent que pour les deux stocks analysés, aucune de ces trois mesures de gestion (contrôle des gains) ne serait bénéfique, à la fois pour le stock et pour la flottille (sur le long- et le moyen terme) lorsqu'elles sont comparées aux projections dans le temps du statu quo. Améliorer la sélectivité de l'engin de pêche est plus avantageux que le fait de limiter l'effort nominal ou d'augmenter le coût de l'effort de pêche. En comparant les performances des stratégies de gestion sur deux stocks, l'un lourdement exploité, et l'autre plus modérement, nous montrons qu'aucune des ces mesures n'est capable de redresser la situation, de façon substantielle, d'un stock intensément exploité, ce qui implique que des mesures plus strictes doivent être envisagées pour la reconstitution complète de ces stocks de crevettes rouges. © EDP Sciences, IFREMER, IRD 2006 ; This study was partly funded by the European Commission through research projects COCTEL (ref. EC DG XIV Copemed-FAO C97/018) and BEMMFISH (ref. EC Q5RS-2001-01533) ; Peer Reviewed

The Multiannual Management Plan embedded in Regulation EU 2019/1022 of the European Parliament and of the Council of June 20, 2019, envisages to reform Mediterranean demersal fisheries to restore stocks to maximum sustainability yields by 2025. This paper leverages a bioeconomic model based on a specific case study of the Western Mediterranean Sea to analyze the objectives of this new EU reform. We complement this analysis with simulations based on alternative management strategies: the reduction of fishing effort of 1–2 days-per-week and changes to selectivity patterns. Effects on artisanal fleets are also analyzed in order to assess scenarios that could achieve sustainability for all demersal fishing fleets. The results reveal that it is not possible to achieve the plan's aims for all stocks. Furthermore, the fishing time established is insufficient, although it would increase economic, and biological indicators for medium- and long-term periods. The best scenarios would be achieved by applying selective changes that provide for faster recovery of biological and economic indicators for trawler and artisanal fleets. The results also reveal that the reduction in the number of fishing days per week complemented with selectivity changes would have a lower socioeconomic impact than a reduction in fishing effort based entirely on fishing days or number of boats. In any case, Mediterranean demersal fisheries require a significant and well-planned reduction in fishing mortality levels over the next several years to recover and maintain sustainable exploitation. ; The authors declare that this study received funding from the European Parliament's Committee on Fisheries and was presented at the European Parliament in Brussels on November 23, 2018. This study received funding from the European Commission's Horizon 2020 Research and Innovation Program under Grant Agreement No. 634495 for the project, "Science, Technology, and Society Initiative to Minimize Unwanted Catches in European Fisheries" (MINOUW) and IS was grant funded by the University of Alicante and Sacyr Agua S.L.

14 pages, 5 figures, 14 tables, 4 appendixes ; A bioeconomic model was built to assess the contribution of more selective trawl nets to the objectives of the European Multi-Annual Plan for demersal fisheries in the Western Mediterranean (WM MAP). The biological submodel was parameterized with age-structured population parameters for the five target stocks in the WM MAP (European hake, red mullet, deep-water rose shrimp, Nephrops and red shrimp) with a sixth stock combining the remaining commercial by catch and following a biomass dynamics model. The trawl fleet was composed of three fleet segments, according to Vessel Length class (VL1218, VL1824, VL2440), practicing two métiers: coastal mixed demersal fishery and deep-water crustacean fishery. The technological solutions analyzed are two simple technical modifications to the otter bottom trawl and based on i) using a panel of meshes turned 90° (T90) in the extension of the trawl net, and ii) inserting a selective grid built from 40 mm square mesh (SM40) netting into the extension of the trawl net. The Results show that, in terms of policy objectives, the reduction in the values of fishing mortality achieved with these selectivity modifications would be insufficient to reach the target fishing mortality at maximum sustainable yield (Fmsy) prescribed in the WM MAP by 2025. However, model results project a substantial recovery of hake and red mullet stock biomass. The recovery of these two important stocks would help improve the evolution of the economic indicators, resulting generally in higher income, profits and salaries in the short (2025) and mid term (2030) ; Funding was provided by the research projects CriMa (Spanish Ministry for Science and Innovation, RTI2018-095770-B-I00) and the Mediterranean Marine Initiative of WWF and the Adessium Foundation (contract nº: 351/2018/9E204550/AD17–39-44). With funding from the Spanish government through the 'Severo Ochoa Centre of Excellence' accreditation (CEX2019-000928-S) ; Peer reviewed

12 pages, 8 figures, 6 tables ; [EN] Minimizing unwanted catches is a major milestone for achieving sustainable fisheries. In the framework of the Common Fisheries Policy, a landing obligation is being established progressively in European waters (Article 15, EU Regulation 1380/2013). Supplementary management measures have been proposed to support and enhance the effectiveness of this new regime. In this context, the effect of the landing obligation on a demersal mixed fishery (coastal and trawl fleet) in the Aegean Sea (NE Mediterranean Sea) was assessed in terms of both biological and economic sustainability. Our results show that the landing obligation alone does not ensure sustainable fisheries. Management action should be directed to the introduction of additional measures. Evidence suggests that improving selectivity and protecting the nursery grounds are possible solutions to decrease discards and ensure sustainable fisheries in the long term. The landing obligation can have a role in incentivizing the adoption of these management measures that ensure lower fishing mortality on juvenile fish ; [ES] Minimizar las capturas no deseadas es un hito importante para lograr pesquerías sostenibles. En el marco de la Política Pesquera Común se está estableciendo progresivamente una obligación de desembarque en aguas europeas (artículo 15, reglamento 1380/2013 de la UE). Se han propuesto medidas de gestión complementarias para apoyar y mejorar la eficacia de este nuevo régimen. En este contexto, se evalúa el efecto de la obligación de desembarque en una pesquería mixta demersal (flota costera y de arrastre) en el mar Egeo (NE mar Mediterráneo), tanto en términos de sostenibilidad biológica como económica. Nuestros resultados muestran que la obligación de desembarque por sí sola no garantiza una pesca sostenible, y que la gestión debería enfocarse hacia la introducción de medidas adicionales. Las evidencias obtenidas sugieren que mejorar la selectividad de las artes de pesca y proteger las áreas de alevinaje son dos soluciones posibles para disminuir los descartes y garantizar una pesca sostenible a largo plazo. La obligación de desembarque puede tener un papel en incentivar la adopción de estas medidas de gestión, que aseguran una menor mortalidad por pesca en peces juveniles ; This work is part of the PhD thesis of the first author, conducted at the Aristotle University of Thessaloniki and has received funding from the European Commission's Horizon 2020 Research and Innovation Programme under Grant Agreement No. 634495 (MINOUW) ; Peer Reviewed