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Auteur (up) Bailleul, D.; Mackenzie, A.; Sacchi, O.; Poisson, F.; Bierne, N.; Arnaud‐Haond, S.
Titre Large-scale genetic panmixia in the blue shark (Prionace glauca): A single worldwide population, or a genetic lag-time effect of the “grey zone” of differentiation? Type Article scientifique
Année 2018 Publication Revue Abrégée Evolutionary Applications
Volume 11 Numéro 5 Pages 614-630
Mots-Clés blue shark; conservation; fisheries; genetic panmixia; Prionace glauca; stock
Résumé The blue shark Prionace glauca, among the most common and widely studied pelagic sharks, is a top predator, exhibiting the widest distribution range. However, little is known about its population structure and spatial dynamics. With an estimated removal of 10–20 million individuals per year by fisheries, the species is classified as “Near Threatened” by International Union for Conservation of Nature. We lack the knowledge to forecast the long-term consequences of such a huge removal on this top predator itself and on its trophic network. The genetic analysis of more than 200 samples collected at broad scale (from Mediterranean Sea, North Atlantic and Pacific Oceans) using mtDNA and nine microsatellite markers allowed to detect signatures of genetic bottlenecks but a nearly complete genetic homogeneity across the entire studied range. This apparent panmixia could be explained by a genetic lag-time effect illustrated by simulations of demographic changes that were not detectable through standard genetic analysis before a long transitional phase here introduced as the “population grey zone.” The results presented here can thus encompass distinct explanatory scenarios spanning from a single demographic population to several independent populations. This limitation prevents the genetic-based delineation of stocks and thus the ability to anticipate the consequences of severe depletions at all scales. More information is required for the conservation of population(s) and management of stocks, which may be provided by large-scale sampling not only of individuals worldwide, but also of loci genomewide.
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Volume de collection Numéro de collection Edition
ISSN 1752-4571 ISBN Médium
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Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 2353
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Auteur (up) Barbraud, C.; Bertrand, A.; Bouchón, M.; Chaigneau, A.; Delord, K.; Demarcq, H.; Gimenez, O.; Torero, M.G.; Gutiérrez, D.; Oliveros‐Ramos, R.; Passuni, G.; Tremblay, Y.; Bertrand, S.
Titre Density dependence, prey accessibility and prey depletion by fisheries drive Peruvian seabird population dynamics Type Article scientifique
Année 2018 Publication Revue Abrégée Ecography
Volume 41 Numéro 7 Pages 1092-1102
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Résumé In marine ecosystems top predator populations are shaped by environmental factors affecting their prey abundance. Coupling top predators’ population studies with independent records of prey abundance suggests that prey fluctuations affect fecundity parameters and abundance of their predators. However, prey may be abundant but inaccessible to their predators and a major challenge is to determine the relative importance of prey accessibility in shaping seabird populations. In addition, disentangling the effects of prey abundance and accessibility from the effects of prey removal by fisheries, while accounting for density dependence, remains challenging for marine top predators. Here, we investigate how climate, population density, and the accessibility and removal of prey (the Peruvian anchovy Engraulis ringens) by fisheries influence the population dynamics of the largest sedentary seabird community (≈ 4 million individuals belonging to guanay cormorant Phalacrocorax bougainvillii, Peruvian booby Sula variegata and Peruvian pelican Pelecanus thagus) of the northern Humboldt Current System over the past half-century. Using Gompertz state–space models we found strong evidence for density dependence in abundance for the three seabird species. After accounting for density dependence, sea surface temperature, prey accessibility (defined by the depth of the upper limit of the subsurface oxygen minimum zone) and prey removal by fisheries were retained as the best predictors of annual population size across species. These factors affected seabird abundance the current year and with year lags, suggesting effects on several demographic parameters including breeding propensity and adult survival. These findings highlight the effects of prey accessibility and fishery removals on seabird populations in marine ecosystems. This will help refine management objectives of marine ecosystems in order to ensure sufficient biomass of forage fish to avoid constraining seabird population dynamics, while taking into account of the effects of environmental variability.
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Langue en Langue du Résumé Titre Original
Éditeur de collection Titre de collection Titre de collection Abrégé
Volume de collection Numéro de collection Edition
ISSN 1600-0587 ISBN Médium
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Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 2376
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Auteur (up) Barde, J.; Bonhommeau, S.; Chassot, E.; Motah, B.
Titre Coastal Mapping And Kitesurfing Type Article scientifique
Année 2018 Publication Revue Abrégée ISPRS – International Archives of the Photogrammetry, Remote Sensing and Spatial Information Science
Volume Xlii-4/W8 Numéro Pages 3-10
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Résumé
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ISSN 2194-9034 ISBN Médium
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Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 2514
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Auteur (up) Batsleer, J.; Marchal, P.; Vaz, S.; Vermard, V.; Rijnsdorp, A.D.; Poos, J.J.
Titre Exploring habitat credits to manage the benthic impact in a mixed fishery Type Article scientifique
Année 2018 Publication Revue Abrégée Mar. Ecol.-Prog. Ser.
Volume 586 Numéro Pages 167-179
Mots-Clés growth; sea; reserves; marine protected areas; juvenile; Plaice; Eastern English Channel; Fleet dynamics; vms data; fishing disturbance; central english-channel; Cod; costs; Dynamic state variable modelling; georges bank; Mixed fisheries; tac; Total allowable catch
Résumé The performance of a combined catch quota and habitat credit system was explored to manage the sustainable exploitation of a mix of demersal fish species and reduce the benthic impacts of bottom trawl fisheries using a dynamic state variable model approach. The model was parameterised for the Eastern English Channel demersal mixed fishery using otter trawls or dredges. Target species differed in their association with habitat types. Restricting catch quota for plaice and cod had a limited effect on benthic impact, except when reduced to very low values, forcing the vessels to stay in port. Quota management had a minimal influence on fishing behaviour and hence resulted in a minimal reduction of benthic impact. Habitat credits may reduce the benthic impacts of the trawl fisheries at a minimal loss of landings and revenue, as vessels are still able to reallocate their effort to less vulnerable fishing grounds, while allowing the fishery to catch their catch quota and maintain their revenue. Only if they are reduced to extremely low levels can habitat credits potentially constrain fishing activities to levels that prevent the fisheries from using up the catch quota for the target species.
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Langue English Langue du Résumé Titre Original
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Volume de collection Numéro de collection Edition
ISSN 0171-8630 ISBN Médium
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Numéro d'Appel MARBEC @ alain.herve @ collection 2283
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Auteur (up) Baudrier, J.; Lefebvre, A.; Galgani, F.; Saraux, C.; Doray, M.
Titre Optimising French fisheries surveys for marine strategy framework directive integrated ecosystem monitoring Type Article scientifique
Année 2018 Publication Revue Abrégée Marine Policy
Volume 94 Numéro Pages 10-19
Mots-Clés Fisheries surveys; Integrated ecosystem monitoring; Marine management, Data Collection Framework; Marine Strategy Framework Directive; Monitoring programme
Résumé The French initial assessment of the Marine Strategy Framework Directive (MSFD) highlighted the lack of reliable data concerning offshore areas. During the planning of the monitoring programmes, the scientists therefore proposed to partially cover this gap by using existing fisheries research vessel surveys deployed for the purposes of the Common Fisheries Policy (CFP). This paper describes ways of improving the effectiveness of these surveys and making them better suited to delivering the information needed for the MSFD. The process took two years and became operational at the beginning of the year 2016. Testing phases from October 2013 to August 2015 had to be organized to fit within the ongoing fisheries tasks without significantly increasing the workload in terms of both time and human resources. Six fisheries research surveys henceforth collect new data, with or without additional sampling techniques. Specific examples are given with litter and hydrological data which will be used to assess the environmental status of French marine waters. The paper also identifies certain limitations regarding this approach. This French experiment enabled more efficient and effective use of current data collection efforts, while optimising vessel time and implementing an ecosystem approach in collecting data for fisheries management.
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ISSN 0308-597x ISBN Médium
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Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 2357
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