Drifting FADs used in tuna fisheries: an ecological trap? Auteur(s) : Marsac, F Fonteneau, Alain Menard, Frederic Éditeur(s) : Pêche thonière et dispositifs de concentration de poissons, Caribbean-Martinique, 15-19 Oct 1999 Résumé : This paper discusses the hypothesis that small tunas and the various species found in association with drifting fads (such as "mahi-mahi", rainbow runner, wahoo, etc.) may be biologically trapped by such a strong association. Massive seeding of drifting artificial fads was observed worldwide during recent years. In this hypothesis, we suggest that fads may alter some biological characteristics of epipelagic populations associated with them: migration, growth, condition factors, predation and natural mortality. As fads are most often used in the equatorial currents, they tend to exhibit zonal drift. Therefore, the associated populations would be artificially transferred from one part of the ocean to another, when they would show different movement patterns in the absence of fads. Natural logs were probably beneficial in terms of ecology and evolution, because they tend to accumulate in convergence areas, most often considered as rich forage areas. Now, fads are seeded in offshore areas, which are not necessarily favourable for tuna feeding. This apparently strong association between fishes and drifting fads may then produce an unexpected biological impact on tuna populations and their associated fauna. The plan is to test this hypothesis in the Atlantic, developing an ad hoc research programme based on tagging, biological and physiological studies, in association to an analysis of high resolution fishery data before and after the development of the fad fishery.Original Abstract: Cet article discute l'hypothese selon laquelle les petits thons et les differentes especes associees a des DCP derivants (comme les coryphenes, elagatis, thazards, etc.) pourraient etre pris dans un piege biologique resultant de cette forte association. Le deploiement massif de DCP artificiels derivants a ete constate a l'echelle mondiale au cours des dernieres annees. Dans cette hypothese, ces DCP, colonises en permanence par de grandes fractions de populations epipelagiques, pourraient modifier les caracteristiques biologiques des especes concernees: leur migration, leur croissance, leurs facteurs de condition, la predation et la mortalite naturelle. Les DCP etant plus frequemment utilises dans les courants equatoriaux, ils tendent a deriver zonalement. Ainsi, les populations associees seraient artificiellement transferees d'un bord a l'autre de l'ocean, alors qu'elles manifesteraient d'autres types de deplacements en l'absence de DCP. Les debris naturels etaient probablement benefiques sur le plan de l'ecologie et de l'evolution car ils s'accumulent dans des zones de convergence le plus souvent considerees comme des zones riches en nourriture. Maintenant, les DCP sont mouilles au large, dans des zones qui peuvent ou non etre favorables a l'alimentation des thons. Cette association apparemment forte entre poissons et DCP derivants pourrait alors causer un impact biologique inattendu sur les populations pelagiques (thons et faune accompagnante). L'objectif est de tester cette hypothese dans l'Atlantique au moyen d'un programme de recherche s'appuyant sur du marquage et des etudes biologiques et physiologiques, parallelement a une analyse des donnees de peche (tailles et CPUE, avant et apres le deploiement des DCP derivants). Droits : info:eu-repo/semantics/openAccess http://archimer.ifremer.fr/doc/00042/15303/12636.pdf http://archimer.ifremer.fr/doc/00042/15303/ | Partager |
Biogeography of tuna and billfish communities Auteur(s) : Reygondeau, Gabriel Maury, Olivier Beaugrand, Gregory Fromentin, Jean-marc Fonteneau, Alain Cury, Philippe Éditeur(s) : Wiley-blackwell Résumé : Aim The aims of this study were: (1) to identify global communities of tuna and billfish species through quantitative statistical analyses of global fisheries data; (2) to describe the spatial distribution, main environmental drivers and species composition of each community detected; and (3) to determine whether the spatial distribution of each community could be linked to the environmental conditions that affect lower trophic levels by comparing the partitions identified in this study with Longhursts biogeochemical provinces. Location The global ocean from 60 degrees S to 65 degrees N. Methods We implemented a new numerical procedure based on a hierarchical clustering method and a nonparametric probabilistic test to divide the oceanic biosphere into biomes and ecoregions. This procedure was applied to a database that comprised standardized data on commercial longline catches for 15 different species of tuna and billfish over a period of more than 50 years (i.e. 1953-2007). For each ecoregion identified (i.e. characteristic tuna and billfish community), we analysed the relationships between species composition and environmental factors. Finally, we compared the biogeochemical provinces of Longhurst with the ecoregions that we identified. Results Tuna and billfish species form nine well-defined communities across the global ocean. Each community occurs in regions with specific environmental conditions and shows a distinctive species composition. High similarity (68.8% homogeneity) between the spatial distribution of the communities of tuna and billfish and the biogeochemical provinces suggests a strong relationship between these species and the physical and chemical characteristics of the global ocean. Main conclusions Despite their high tolerance for a wide range of environmental conditions, these highly migratory species are partitioned into clear geographical communities in the ocean at a global scale. The similarity between biogeochemical and biotic divisions in the ocean suggests that the global ocean is a mosaic of large biogeographical ecosystems, each characterized by specific environmental conditions that have a strong effect on the composition of the trophic web. Journal Of Biogeography (0305-0270) (Wiley-blackwell), 2012-01 , Vol. 39 , N. 1 , P. 114-129 Droits : 2011 Blackwell Publishing Ltd http://archimer.ifremer.fr/doc/00060/17141/14716.pdf DOI:10.1111/j.1365-2699.2011.02582.x http://archimer.ifremer.fr/doc/00060/17141/ | Partager Voir aussi Biogeochemical provinces global ocean Istiophorus Katsuwonus macroecology Makaira marine biogeography Tetrapturus Thunnus Xiphias Télécharger |
The True Challenge of Giant Marine Reserves Auteur(s) : Kaplan, David Bach, Pascal Bonhommeau, Sylvain Chassot, Emmanuel Chavance, Pierre Dagorn, Laurent Davies, Tim Dueri, Sibylle Éditeur(s) : Amer Assoc Advancement Science Science (0036-8075) (Amer Assoc Advancement Science), 2013-05 , Vol. 340 , N. 6134 , P. 810-811 Droits : 2013 American Association for the Advancement of Science. All Rights Reserved. http://archimer.ifremer.fr/doc/00139/25068/23186.pdf DOI:10.1126/science.340.6134.810-b http://archimer.ifremer.fr/doc/00139/25068/ | Partager |
Patterns of variations in large pelagic fish: A comparative approach between the Indian and the Atlantic Oceans Auteur(s) : Corbineau, A. Rouyer, Tristan Fromentin, Jean-marc Cazelles, B. Fonteneau, Alain Menard, Frederic Éditeur(s) : Pergamon-elsevier Science Ltd Résumé : Catch data of large pelagic fish such as tuna, swordfish and billfish are highly variable ranging from short to long term. Based on fisheries data, these time series are noisy and reflect mixed information on exploitation (targeting, strategy, fishing power), population dynamics (recruitment, growth, mortality, migration, etc.), and environmental forcing (local conditions or dominant climate patterns). In this work, we investigated patterns of variation of large pelagic fish (i.e. yellowfin tuna, bigeye tuna, swordfish and blue marlin) in Japanese longliners catch data from 1960 to 2004. We performed wavelet analyses on the yearly time series of each fish species in each biogeographic province of the tropical Indian and Atlantic Oceans. In addition, we carried out cross-wavelet analyses between these biological time series and a large-scale climatic index, i.e. the Southern Oscillation Index (Sol). Results showed that the biogeographic province was the most important factor structuring the patterns of variability of Japanese catch time series. Relationships between the SOI and the fish catches in the Indian and Atlantic Oceans also pointed out the role of climatic variability for structuring patterns of variation of catch time series. This work finally confirmed that Japanese longline CPUE data poorly reflect the underlying population dynamics of tunas. (C) 2010 Elsevier Ltd. All rights reserved. Progress In Oceanography (0079-6611) (Pergamon-elsevier Science Ltd), 2010-07 , Vol. 86 , N. 1-2 , P. 276-282 Droits : 2010 Elsevier B.V. All rights reserved. http://archimer.ifremer.fr/doc/00011/12231/9029.pdf DOI:10.1016/j.pocean.2010.04.019 http://archimer.ifremer.fr/doc/00011/12231/ | Partager |
DCP employés par les pêcheries artisanales et industrielles : une question d'échelle. L’utilisation et le développement technique des DCP au coeur de la conférence de Tahiti sur les DCP ; Artisanal and industrial FADs: A question of scale. Tahiti conference reviews current FAD use and technology Auteur(s) : Taquet, Marc Blanc, Michel Dagorn, Laurent Filmalter, John David Fonteneau, Alain Forget, Fabien Gaertner, Jean-claude Galzin, René Éditeur(s) : SPC Fisheries Newsletter (0248-076X) (SPC), 2011-09 , Vol. 136 , P. 35-45 Droits : info:eu-repo/semantics/openAccess http://archimer.ifremer.fr/doc/00115/22657/20383.pdf http://archimer.ifremer.fr/doc/00115/22657/20384.pdf http://archimer.ifremer.fr/doc/00115/22657/ | Partager |
A worldwide review of purse seine fisheries on FADs Auteur(s) : Fonteneau, Alain Pallares, P Pianet, Renaud Éditeur(s) : Pêche thonière et dispositifs de concentration de poissons, Caribbean-Martinique, 15-19 Oct 1999 Résumé : This paper develops a comparative overview of the development of Fish Aggregating Devices (or fads) by the tropical purse seine fisheries in various ocean areas (Atlantic, Indian, Western and Eastern Pacific Oceans). First, a comparative review of fishery statistics is developed. Recent catches on fads by purse seiners can be estimated at a level of one million tons yearly. This comparison allows to describe the fishing zones and catch trends over time, the species composition and size taken in the various fad fisheries. Skipjack tuna is the dominant species in most fad fisheries, but significant amounts of yellowfin and bigeye are also frequently taken under fads. The paper also presents an overview of various observer data concerning the by-catches of the various fisheries using fads. This comparison allows to estimate the total worldwide yearly by-catches at about 100,000 t, and their species composition in each ocean. The fad technology used in the various oceans by purse seiners is described. The recent use of fads by purse seiners has introduced major uncertainties in most stock assessments, because analyses are hampered by changes in the fishing effort in a fad fishery, by changes in fishing zones and in sizes caught. As a last point, the management of fads presently done or in view by the various tuna bodies are introduced. It appears that the present massive use of fads worldwide is perhaps an unsafe fishing mode, which could produce serious overfishing of many stocks. There is then a consensus that the use of fads needs to be controlled and limited to sustainable biological levels. Droits : Ifremer http://archimer.ifremer.fr/doc/00042/15278/12664.pdf http://archimer.ifremer.fr/doc/00042/15278/ | Partager |