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| Hinke, Jefferson T; Pacific Fisheries Environmental Laboratory and Joint Institute for Marine and At; jhinke@pfeg.noaa.gov; Kaplan, Isaac C; Center for Limnology, University of Wisconsin; ickaplan@wisc.edu; Aydin, Kerim; Alaska Fisheries Science Center; Kerim.Aydin@noaa.gov; Watters, George M; Pacific Fisheries Environmental Laboratory; gwatters@pfeg.noaa.gov; Olson, Robert J; Inter-American Tropical Tuna Commission; rolson@iattc.org; Kitchell, James F. K.; Center for Limnology, University of Wisconsin; kitchell@mhub.limnology.wisc.edu. |
| We use food-web models to develop visualizations to compare and evaluate the interactions of tuna fisheries with their supporting food webs in the eastern tropical Pacific (ETP) and the central north Pacific (CNP) Oceans. In the ETP and CNP models, individual fisheries use slightly different food webs that are defined by the assemblage of targeted tuna species. Distinct energy pathways are required to support different tuna species and, consequently, the specific fisheries that target different tuna assemblages. These simulations suggest that catches of tunas, sharks, and billfishes have lowered the biomass of the upper trophic levels in both systems, whereas increases in intermediate and lower trophic level animals have accompanied the decline of top... |
| Tipo: Peer-Reviewed Reports |
Palavras-chave: Ecosystem modeling; Food webs; Longline fishing; Purse-seine fishing; Tunas; Trophic levels; Pacific Ocean. |
| Ano: 2004 |
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| Bertrand, Arnaud; Josse, Erwan; Bach, Pascal; Gros, Philippe; Dagorn, Laurent. |
| We studied relationships between tropical tunas (albacore (Thunnus alalunga), bigeye (Thunnus obesus), and yellowfin (Thunnus albacares)) and their biotic and abiotic environments through simultaneous acoustic observations of tunas and their prey, experimental longline catch, and oceanographic data in French Polynesia. Vertical habitat limits were estimated based on temperature and dissolved oxygen at capture data. We then studied tuna-micronekton relationships to better understand how tuna occupy the pelagic space, At a regional scale, tunas were more abundant in areas rich in prey with favourable hydrological conditions. Inside such areas, at the scale of a longline set, however, the longline catches were maximal only when prey were not distributed in... |
| Tipo: Text |
Palavras-chave: Hydrological; Acoustic observations; Tunas. |
| Ano: 2002 |
URL: http://archimer.ifremer.fr/doc/2002/publication-733.pdf |
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| Fonteneau, Alain; Fromentin, Jean-marc. |
| This paper develops a critical overview of the various problems and uncertainties faced in tuna stock assessment, management and conservation. This presentation is based on Atlantic tunas, but also on various tuna stocks worldwide. Tuna jisheries management is characterized by major uncertainties in the stock assessment; since these stock assessments are always done only on jishery data which are often biased. Fortunately most tuna stocks are showing a strong resistance to overfishing. These major characteristics of tuna stocks and jisheries, and the bias in the scientific analysis, are presented and discussed. As a result, many of the reference point recommended for the precautionary approach applied to jisheries are often quite inappropriate for tuna... |
| Tipo: Text |
Palavras-chave: Tunas; Precautionay approach; Atlantic; Management; Assessment. |
| Ano: 2000 |
URL: http://archimer.ifremer.fr/doc/00194/30564/28984.pdf |
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