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Auteur (up) Ortega-Cisneros, K.; Shannon, L.; Cochrane, K.; Fulton, E. A.; Shin, Y.-J.
Titre Evaluating the specificity of ecosystem indicators to fishing in a changing environment: A model comparison study for the southern Benguela ecosystem Type Article scientifique
Année 2018 Publication Revue Abrégée Ecological Indicators
Volume 95 Numéro Pages 85-98
Mots-Clés Ecosystem models; Environmental change; Fishing; Indicators; Specificity; Upwelling
Résumé Ecological indicators used to monitor fishing effects in the context of climate change and variability need to be informative to enable effective ecosystem-based fisheries management. We evaluated the specificity of the response of ecosystem indicators to different fishing and environmental pressure levels using Ecosim and Atlantis ecosystem models for the southern Benguela ecosystem. Three fishing strategies were modelled to represent a variety of ways of targeting fishing within an ecosystem: one focused on low trophic levels (i.e. forage species), another on higher trophic levels (i.e. predatory fish) and a third tested fishing pressure across the full range of potentially exploitable species. Two types of environmental change were simulated for each fishing mortality scenario – random environmental variability and directional climate change. The specificity of selected ecological indicators (mean trophic level of the community, proportion of predatory fish, biomass/landings, mean intrinsic vulnerability and marine trophic index) was evaluated for different combinations of fishing strategy, fishing mortality and both types of environmental change. While there were mostly large differences in indicator values computed from the Atlantis and Ecosim models, the specificity of the ecological indicators considered under changing climate generally corresponded between the two models. Certain indicators (i.e. mean trophic level of the community) were less specific in detecting effects of fishing in the southern Benguela for some of the three fishing strategies modelled (i.e. high trophic level fishing strategy) under climate change. This helped refine the most appropriate indicator set for our system, reflecting the focus of a particular fishing strategy, and improved confidence in the suitability of these indicators for monitoring fishing effects in the Southern Benguela.
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Volume de collection Numéro de collection Edition
ISSN 1470-160x ISBN Médium
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Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 2402
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Auteur (up) Pauly, D.; Belhabib, D.; Blomeyer, R.; Cheung, W.W.W.L.; Cisneros-Montemayor, A.Ã.©s M.; Copeland, D.; Harper, S.; Lam, V.W.Y.; Mai, Y.; Le Manach, F.; Österblom, H.; Mok, K.M.; van der Meer, L.; Sanz, A.; Shon, S.; Sumaila, U.R.; Swartz, W.; Watson, R.; Zhai, Y.; Zeller, D.
Titre China's distant-water fisheries in the 21st century Type Article scientifique
Année 2013 Publication Revue Abrégée Fish and Fisheries
Volume Numéro Pages
Mots-Clés Control and Surveillance of fisheries; distant-water fishing; illegal; management; Monte Carlo method; unreported and unregulated (IUU) catch
Résumé We conservatively estimate the distant-water fleet catch of the People's Republic of China for 2000–2011, using a newly assembled database of reported occurrence of Chinese fishing vessels in various parts of the world and information on the annual catch by vessel type. Given the unreliability of official statistics, uncertainty of results was estimated through a regionally stratified Monte Carlo approach, which documents the presence and number of Chinese vessels in Exclusive Economic Zones and then multiplies these by the expected annual catch per vessel. We find that China, which over-reports its domestic catch, substantially under-reports the catch of its distant-water fleets. This catch, estimated at 4.6 million t year−1 (95% central distribution, 3.4–6.1 million t year−1) from 2000 to 2011 (compared with an average of 368 000 t·year−1 reported by China to FAO), corresponds to an ex-vessel landed value of 8.93 billion € year−1 (95% central distribution, 6.3–12.3 billion). Chinese distant-water fleets extract the largest catch in African waters (3.1 million t year−1, 95% central distribution, 2.0–4.4 million t), followed by Asia (1.0 million t year−1, 0.56–1.5 million t), Oceania (198 000 t year−1, 144 000–262 000 t), Central and South America (182 000 t year−1, 94 000–299 000 t) and Antarctica (48 000 t year−1, 8 000–129 000 t). The uncertainty of these estimates is relatively high, but several sources of inaccuracy could not be fully resolved given the constraints inherent in the underlying data and method, which also prevented us from distinguishing between legal and illegal catch.
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Volume de collection Numéro de collection Edition
ISSN 1467-2979 ISBN Médium
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Numéro d'Appel LL @ pixluser @ collection 247
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Auteur (up) Peristeraki, P.; Bitetto, I.; Carbonara, P.; Carlucci, R.; Certain, G.; De Carlo, F.; Gristina, M.; Kamidis, N.; Pesci, P.; Stagioni, M.; Valls, M.; Tserpes, G.
Titre Investigation of spatiotemporal patterns in mean temperature and mean trophic level of MEDITS survey catches in the Mediterranean Sea Type Article scientifique
Année 2019 Publication Revue Abrégée Sci. Mar.
Volume 83 Numéro Pages 165-174
Mots-Clés bottom temperature; climate change; dynamics; fish; fisheries; fishing pressure; mean temperature of the catch; Mediterranean; north; ocean; resources; sea warming; state; trends; trophic level; water
Résumé Mean temperature (MTC) and mean trophic level (MTL) spatiotemporal patterns of MEDITS survey catches were examined in 13 geographic statistical areas (GSAs) of the Mediterranean between 1994 and 2016. The study aimed to detect changes in the demersal community structure related to anthropogenic impacts. A generalized additive modelling approach was used to examine the effects of year and GSA on the MTC and MTL indexes and on bottom temperature by haul. For the MTC index, the year was significant only in 4 GSAs, while for MTC it was significant in 5. Higher MTC values were observed in central and eastern areas. Bottom temperature increased after 2010, and also from west to east and from north to south. Our results indicate that the recently observed increase in bottom sea temperature has not resulted in an immediate response by demersal marine communities, but areas with higher warming rates or shallow depths were found to be more susceptible to sea warming. For MTL,, decreasing trends were observed in only 2 GSAs, while the temporal trends observed in 5 GSAs may have reflected changes in fishing activity patterns. However, higher MTL values were observed in GSAs with generally higher exploitation rates, indicating that factors other than fishing play an important structuring role in marine communities. The present results indicate differences among Mediterranean subareas in regard to changes in the community structure attributed to environmental conditions and exploitation patterns and have implications for the ecology and dynamics of the stocks.
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Editeur Lieu de Publication Éditeur
Langue English Langue du Résumé Titre Original
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Volume de collection Numéro de collection Edition
ISSN 0214-8358 ISBN Médium
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Notes WOS:000504829900013 Approuvé pas de
Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 2708
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Auteur (up) Perry, R.I.; Cury, P.; Brander, K.; Jennings, S.; Mollmann, C.; Planque, B.
Titre Sensitivity of marine systems to climate and fishing: Concepts, issues and management responses Type Article scientifique
Année 2010 Publication Revue Abrégée Journal of Marine Systems
Volume 79 Numéro Pages 427-435
Mots-Clés change; climate; Communities; ecosystems; fisheries; Fishing; management; Populations; variability
Résumé Modern fisheries research and management must understand and take account of the interactions between climate and fishing, rather than try to disentangle their effects and address each separately. These interactions are significant drivers of change in exploited marine systems and have ramifications for ecosystems and those who depend on the services they provide. We discuss how fishing and climate forcing interact on individual fish, marine populations, marine communities, and ecosystems to bring these levels into states that are more sensitive to (i.e. more strongly related with) climate forcing. Fishing is unlikely to alter the sensitivities of individual finfish and invertebrates to climate forcing. It will remove individuals with specific characteristics from the gene pool, thereby affecting structure and function at higher levels of organisation. Fishing leads to a loss of older age classes, spatial contraction, loss of sub-units, and alteration of life history traits in populations, making them more sensitive to climate variability at interannual to interdecadal scales. Fishing reduces the mean size of individuals and mean trophic level of communities, decreasing their turnover time leading them to track environmental variability more closely. Marine ecosystems under intense exploitation evolve towards stronger bottom-up control and greater sensitivity to climate forcing. Because climate change occurs slowly, its effects are not likely to have immediate impacts on marine systems but will be manifest as the accumulation of the interactions between fishing and climate variability – unless threshold limits are exceeded. Marine resource managers need to develop approaches which maintain the resilience of individuals, populations, communities and ecosystems to the combined and interacting effects of climate and fishing. Overall, a less-heavily fished marine system, and one which shifts the focus from individual species to functional groups and fish communities, is likely to provide more stable catches with climate variability and change than would a heavily fished system. Crown Copyright (C) 2009 Published by Elsevier B.V. All rights reserved.
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ISSN 0924-7963 ISBN Médium
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Numéro d'Appel LL @ pixluser @ collection 95
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Auteur (up) PLANQUE, B.; FROMENTIN, J.-M.; CURY, P.; DRINKWATER, K.F.; JENNINGS, S.; PERRY, R.I.; KIFANI, S.
Titre How does fishing alter marine populations and ecosystems sensitivity to climate? Type Article scientifique
Année 2010 Publication Journal of Marine Systems Revue Abrégée
Volume 79 Numéro 3-4 Pages 403-417
Mots-Clés Resilience; Marine ecosystems; Demography; Climate fishing interactions
Résumé Evidence has accumulated that climate variability influences the state and functioning of marine ecosystems. At the same time increasing pressure from exploitation and other human activities has been shown to impact exploited and non-exploited species and potentially modify ecosystem structure. There has been a tendency among marine scientists to pose the question as a dichotomy, i.e., whether (1) “natural” climate variability or (2) fishery exploitation bears the primary responsibility for population declines in fish populations and the associated ecosystem changes. However, effects of both climate and exploitation are probably substantially involved in most cases. More importantly, climate and exploitation interact in their effects, such that climate may cause failure in a fishery management scheme but that fishery exploitation may also disrupt the ability of a resource population to withstand, or adjust to, climate changes. Here, we review how exploitation, by altering the structure of populations and ecosystems, can modify their ability to respond to climate. The demographic effects of fishing (removal of large-old individuals) can have substantial consequences on the capacity of populations to buffer climate variability through various pathways (direct demographic effects, effects on migration, parental effects). In a similar way, selection of population sub-units within metapopulations may also lead to a reduction in the capacity of populations to withstand climate variability and change. At the ecosystem level, reduced complexity by elimination of species, such as might occur by fishing, may be destabilizing and could lead to reduced resilience to perturbations. Differential exploitation of marine resources could also promote increased turnover rates in marine ecosystems, which would exacerbate the effects of environmental changes. Overall (and despite the specificities of local situations) reduction in marine diversity at the individual, population and ecosystem levels will likely lead to a reduction in the resilience and an increase in the response of populations and ecosystems to future climate variability and change. Future management schemes will have to consider the structure and functioning of populations and ecosystems in a wider sense in order to maximise the ability of marine fauna to adapt to future climates. (C) 2009 Elsevier B.V. All rights reserved.
Adresse Univ E Anglia, Sch Environm Sci, Norwich NR4 7TJ, Norfolk, England.
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Editeur Elsevier Lieu de Publication Éditeur
Langue Langue du Résumé Titre Original
Éditeur de collection Titre de collection Titre de collection Abrégé
Volume de collection Numéro de collection Edition
ISSN 0924-7963 ISBN Médium
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Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ 7384 collection 1025
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