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Auteur (down) Travis, J.; Coleman, F.C.; Auster, P.J.; Cury, P.; Estes, J.A.; Orensanz, J.; Peterson, C.H.; Power, M.E.; Steneck, R.S.; Wootton, J.T.
Titre Integrating the invisible fabric of nature into fisheries management Type Article scientifique
Année 2014 Publication Revue Abrégée Proceedings of the National Academy of Sciences of the United States of America
Volume 111 Numéro 2 Pages 581-584
Mots-Clés alternative states; ecosystem flips; fisheries collapse; ocean fisheries
Résumé Overfishing and environmental change have triggered many severe and unexpected consequences. As existing communities have collapsed, new ones have become established, fundamentally transforming ecosystems to those that are often less productive for fisheries, more prone to cycles of booms and busts, and thus less manageable. We contend that the failure of fisheries science and management to anticipate these transformations results from a lack of appreciation for the nature, strength, complexity, and outcome of species interactions. Ecologists have come to understand that networks of interacting species exhibit nonlinear dynamics and feedback loops that can produce sudden and unexpected shifts. We argue that fisheries science and management must follow this lead by developing a sharper focus on species interactions and how disrupting these interactions can push ecosystems in which fisheries are embedded past their tipping points.
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ISSN 0027-8424 ISBN Médium
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Numéro d'Appel LL @ pixluser @ collection 336
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Auteur (down) Travers-Trolet, M.; Shin, Y.-J.; Shannon, L.J.; Moloney, C.L.; Field, J.G.
Titre Combined fishing and climate forcing in the southern Benguela upwelling ecosystem : an end-to-end modelling approach reveals dampened effects Type Article scientifique
Année 2014 Publication Revue Abrégée Plos One
Volume 9 Numéro 4 Pages
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Résumé The effects of climate and fishing on marine ecosystems have usually been studied separately, but their interactions make ecosystem dynamics difficult to understand and predict. Of particular interest to management, the potential synergism or antagonism between fishing pressure and climate forcing is analysed in this paper, using an end-to-end ecosystem model of the southern Benguela ecosystem, built from coupling hydrodynamic, biogeochemical and multispecies fish models (ROMS-N(2)P(2)Z(2)D(2)-OSMOSE). Scenarios of different intensities of upwelling-favourable wind stress combined with scenarios of fishing top-predator fish were tested. Analyses of isolated drivers show that the bottom-up effect of the climate forcing propagates up the food chain whereas the top-down effect of fishing cascades down to zooplankton in unfavourable environmental conditions but dampens before it reaches phytoplankton. When considering both climate and fishing drivers together, it appears that top-down control dominates the link between top-predator fish and forage fish, whereas interactions between the lower trophic levels are dominated by bottom-up control. The forage fish functional group appears to be a central component of this ecosystem, being the meeting point of two opposite trophic controls. The set of combined scenarios shows that fishing pressure and upwelling-favourable wind stress have mostly dampened effects on fish populations, compared to predictions from the separate effects of the stressors. Dampened effects result in biomass accumulation at the top predator fish level but a depletion of biomass at the forage fish level. This should draw our attention to the evolution of this functional group, which appears as both structurally important in the trophic functioning of the ecosystem, and very sensitive to climate and fishing pressures. In particular, diagnoses considering fishing pressure only might be more optimistic than those that consider combined effects of fishing and environmental variability.
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ISSN 1932-6203 ISBN Médium
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Numéro d'Appel LL @ pixluser @ collection 372
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Auteur (down) Travers-Trolet, M.; Shin, Y.-J.; Field, J.
Titre An end-to-end coupled model ROMS-N 2 P 2 Z 2 D 2 -OSMOSE of the southern Benguela foodweb: parameterisation, calibration and pattern-oriented validation Type Article scientifique
Année 2014 Publication Revue Abrégée African Journal of Marine Science
Volume 36 Numéro 1 Pages 11-29
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ISSN 1814-232x, 1814-2338 ISBN Médium
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Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 1499
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Auteur (down) Toussaint, A.; Beauchard, O.; Oberdorff, T.; Brosse, S.; Villeger, S.
Titre Historical assemblage distinctiveness and the introduction of widespread non-native species explain worldwide changes in freshwater fish taxonomic dissimilarity Type Article scientifique
Année 2014 Publication Revue Abrégée Global Ecology and Biogeography
Volume 23 Numéro 5 Pages 574-584
Mots-Clés Beta diversity; differentiation; freshwater fish; homogenization; macroecology; partitioning; turnover
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ISSN 1466-8238 ISBN Médium
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Numéro d'Appel MARBEC @ alain.herve @ collection 1174
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Auteur (down) Torres-Irineo, E.; Gaertner, D.; Chassot, E.; Dreyfus-Leon, M.
Titre Changes in fishing power and fishing strategies driven by newtechnologies : the case of tropical tuna purse seiners in the easternAtlantic Ocean Type Article scientifique
Année 2014 Publication Revue Abrégée Fisheries Research
Volume 155 Numéro Pages 10-19
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Résumé Technological advancements can influence both the fishing power of a fleet and the fishing strategies itemploys. To investigate these potential linkages, we examined almost three decades of data (1981&8211;2008)from French tropical tuna purse seiners operating in the eastern Atlantic Ocean. Applying a sequence ofstatistical methods at different temporal and spatial scales, we analyzed two indicators of fishing power(sets per boat-day on fish aggregating devices (FADs) and sets per boat-day on free-swimming schools)each of which represent a distinct fishing mode. Our results show that the increasing modernizationof this fleet has led to increases in both fishing power and the available number of fishing strategies tochoose from. A key output of this analysis was the breakdown of fishing power time series (for each fishingmode) into separate periods of continuous years during which catchability was assumed to be constant,thus identifying regime shifts. This partitioning allowed us to identify when key changes occurred inthe fishery. Changes in FAD-associated fishing were mostly driven by the introduction of radio beacons(early 1990s) which lead to an increase in fishing effort and an expansion of fishing grounds (directeffect) and the implementation of time-area management measures which resulted in a fragmentationof the traditional fishing grounds in the 2000s (indirect effect). During the same period, fishing on free-swimming schools also increased despite the biomass of stocks decreasing and fishing grounds remainingunchanged. This suggests these increases were driven by improvements in fish detection technology (e.g.,bird radars, sonar). These identified increases are not entirely unexpected: indeed it is widely recognizedthat fishing power in the purse seine tuna fishery has increased over time. However, these increases donot necessarily occur linearly. Thus, understanding how fishing power is changing over time (such asdetermining when regime shifts occur) is critical to improving the CPUE standardization procedure intropical tuna purse seine fisheries.
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Langue eng Langue du Résumé Titre Original
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ISSN 0165-7836 ISBN Médium
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Numéro d'Appel LL @ pixluser @ collection 335
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