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Auteur Beckensteiner, J.; Kaplan, D.M.; Scheld, A.M.
Titre Barriers to Eastern Oyster Aquaculture Expansion in Virginia Type Article scientifique
Année 2020 Publication Revue Abrégée Front. Mar. Sci.
Volume 7 Numéro Pages 53
Mots-Clés beta regression; Chesapeake Bay; conservation; Crassostrea virginica; crassostrea-virginica; ecosystem services; impact; management; marine aquaculture; oyster aquaculture; political economics; restoration; social acceptability; spatial management; user conflicts
Résumé The eastern oyster once provided major societal and ecosystem benefits, but these benefits have been threatened in recent decades by large declines in oyster harvests. In many areas, recovery of oyster aquaculture faces significant societal opposition and spatial constraints limiting its ability to meet expectations regarding future food needs and provision of ecosystem services. In Virginia, oyster aquaculture has begun to expand, concurrent with an increase in subaqueous leased areas (over 130,000 acres of grounds are currently leased). Though private leases must in theory be used for oyster production, in practice, they can be held for other reasons, such as speculation or intentional exclusion of others. These factors have led to large variation over time and space in the use of leases in lower Chesapeake Bay; and privately leased grounds are now thought to be underutilized for oyster production. This research examined potential barriers to expansion of oyster aquaculture in Virginia. We first evaluated if a lack of space was limiting industry expansion and quantified temporal and spatial trends in the use and productivity of leases. Then, differences in used and non-used leases were investigated in relation to variables thought to be related to “not in my backyard” attitudes, congestion, speculation, local economic and environmental conditions. Finally, the performance of the Virginia leasing system was compared with those in other states along the U.S. East and Gulf Coasts. We found limited evidence for spatial constraints on aquaculture leasing, but strong evidence for social and regulatory inefficiencies. Although rates of lease use increased from 2006 to 2016, only 33% of leases were ever used for oyster production and about 63% of leaseholders reported no commercial harvests. Non-used leases tended to be smaller, and were found in more populated, high-income regions, consistent with both speculative and exclusionary uses. Virginia had the second lowest level of total production of cultured oysters per leased acre among the states on the East and Gulf Coasts of the United States. These results indicate that there is room for oyster aquaculture expansion in Virginia if societal, regulatory, and economic barriers can be reduced or if existing leased areas are used more efficiently.
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Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 2748
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Auteur Chaboud, C.; Vendeville, P.
Titre Evaluation of selectivity and bycatch mitigation measures using bioeconomic modelling. The cases of Madagascar and French Guiana shrimp fisheries Type Article scientifique
Année 2011 Publication Revue Abrégée Aquatic Living Resources
Volume 24 Numéro 2 Pages 137-148
Mots-Clés Bioeconomics; Bycatch; mitigation; modelling; selectivity; Shrimp fisheries
Résumé Tropical shrimp fisheries are characterized by various interactions with their natural environment and with other fisheries. These latter interactions can be explained by the high quantity of bycatch taken by industrial trawler fleets, which has a significant impact on fish populations associated with shrimps and thus also on finfish fisheries. Bycatch also includes emblematic species, which are subject to strict conservation measures decided by the international community. It seems important to identify and assess the biological and economic consequences of different mitigation measures (increase of mesh size, turtle excluder devices and bycatch reducing devices). This communication is based on case studies undertaken on the Indian white prawn (Fenneropenaeus indicus) and speckled shrimp (Metapenaeus monoceros) fisheries in Madagascar and on the brown shrimp (Farfantepenaeus subtilis) and pink spotted shrimp (Farfantepenaeus brasiliensis) fishery in French Guiana. A review of the impacts of these fisheries on resources and ecosystems is made and some results of experiments on mitigation devices given. Finally, the results of simulations obtained using a multi-species, multi-fleet, age-structured bioeconomic model, including modifications of catchability and costs related to the adoption of these devices, is presented and discussed.
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ISSN 0990-7440 ISBN Médium
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Numéro d'Appel LL @ pixluser @ collection 128
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Auteur Mullon, C.; Mittaine, J.F.; Thébaud, O.; Péron, G.; Merino, G.; Barange, M.
Titre Modeling the global fishmeal and fish oil markets Type Article scientifique
Année 2009 Publication Revue Abrégée Natural Resource Modeling
Volume 22 Numéro 4 Pages 564-609
Mots-Clés Bio-economic modeling; fishmeal; fish oil; networks economics; small pelagic fisheries
Résumé To explore the drivers of change in the complex system relating small pelagic fisheries and fishmeal/fish oil markets, to identify the interactions between these drivers and their overall impacts, we propose a bio-economic model, coupling the ecological and the economic dynamics of these global commodities. The model enables an analysis of the consequences of both global and local changes in the environment of production systems. Through sensitivity analysis of specific input parameters, we evaluate the robustness of the overall system to such changes and show that local responses of production systems and markets cannot be considered in isolation from the set of interactions at global level.
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ISSN 0890-8575 ISBN Médium
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Numéro d'Appel LL @ pixluser @ collection 41
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Auteur Rabearisoa, N.; Sabarros, P. S.; Romanov, E. V.; Lucas, V.; Bach, P.
Titre Toothed whale and shark depredation indicators: A case study from the Reunion Island and Seychelles pelagic longline fisheries Type Article scientifique
Année 2018 Publication Revue Abrégée PLOS ONE
Volume 13 Numéro 8 Pages e0202037
Mots-Clés Indian Ocean; Seychelles; Sharks; Tuna; Fisheries; Economics; Killer whales; Whales
Résumé Depredation in marine ecosystems is defined as the damage or removal of fish or bait from fishing gear by predators. Depredation raises concerns about the conservation of species involved, fisheries yield and profitability, and reference points based on stock assessment of depredated species. Therefore, the development of accurate indicators to assess the impact of depredation is needed. Both the Reunion Island and the Seychelles archipelago pelagic longline fisheries targeting swordfish (Xiphias gladius) and tuna (Thunnus spp.) are affected by depredation from toothed whales and pelagic sharks. In this study, we used fishery data collected between 2004 and 2015 to propose depredation indicators and to assess depredation levels in both fisheries. For both fisheries, the interaction rate (depredation occurrence) was significantly higher for shark compared to toothed whale depredation. However, when depredation occurred, toothed whale depredation impact was significantly higher than shark depredation impact, with higher depredation per unit effort (number of fish depredated per 1000 hooks) and damage rate (proportion of fish depredated per depredated set). The gross depredation rate in the Seychelles was 18.3%. A slight increase of the gross depredation rate was observed for the Reunion Island longline fleet from 2011 (4.1% in 2007–2010 and 4.4% in 2011–2015). Economic losses due to depredation were estimated by using these indicators and published official statistics. A loss of 0.09 EUR/hook due to depredation was estimated for the Reunion Island longline fleet, and 0.86 EUR/hook for the Seychelles. These results suggest a southward decreasing toothed whale and shark depredation gradient in the southwest Indian Ocean. Seychelles depredation levels are among the highest observed in the world revealing this area as a “hotspot” of interaction between pelagic longline fisheries and toothed whales. This study also highlights the need for a set of depredation indicators to allow for a global comparison of depredation rates among various fishing grounds worldwide.
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Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 2401
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