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Registros recuperados: 11
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Analysis of the potential impact of several management measures for eastern Atlantic bluefin tuna on the basis of yield per recruit ArchiMer
Arrizabalaga, Haritz; Restrepo, Victor; Fromentin, Jean-marc; Ortiz De Urbina, J M.
A standard yield per recruit (YPR) analysis is used to analyse the effects of minimum size regulations and time area closures on bluefin tuna from the eastern stock (east Atlantic and Mediterranean). Analyses were based on a fishing mortality vector computed over the period 1990-1994 for which data were more reliable and VPA (performed during the 2002 stock assessment) showed a relatively good convergence. This fishing mortality vector was modified according to some combinations of minimum size regulations and time area closures. It is concluded that: (i) PSmed is the main contributor to catch at age in the range of ages 1-13; (ii) The minimum size regulations considered would increase the YPR more than the time area closures, but these would enhance SPR...
Tipo: Text Palavras-chave: Yield/recruit; Yield predictions; Size limit regulations; Time-area closures; Bluefin tuna.
Ano: 2007 URL: http://archimer.ifremer.fr/doc/00192/30329/28806.pdf
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Can we detect the effects of environmental variations on fish populations through VPA outputs? the North Atlantic albacore case ArchiMer
Kell, Laurence T; Fromentin, Jean-marc; Ortiz De Zarate, Victoria; Arrizabalaga, Haritz.
Past studies have indicated that numbers-at-age 1 of albacore may be correlated with the winter NAO index in the previous year. Two main hypotheses have been stressed to explain such observation, i.e. an impact of the NAO on the recruitment or on migration patterns and consequently in the availability and catchability of specific age classes to the surface fishery. The objective of the present paper is to test whether such processes can be distinguished using VPA outputs. We first computed simple cross-correlations between the NAO at various lags, catches-at-age, Numbers-atage and F-at-age estimated in the last assessment. Since results were inconclusive, simulations were undertaken. The results showed that the probability of detecting spurious...
Tipo: Text Palavras-chave: Thunnus alalunga; North Atlantic Oscillation; Simulation model; Virtual population analysis; Correlation coefficient; NAO.
Ano: 2005 URL: http://archimer.ifremer.fr/doc/00194/30503/28913.pdf
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Determining natal origin for improved management of Atlantic bluefin tuna ArchiMer
Rodríguez‐ezpeleta, Naiara; Díaz‐arce, Natalia; Walter, John F; Richardson, David E; Rooker, Jay R; Nøttestad, Leif; Hanke, Alex R; Franks, James S; Deguara, Simeon; Lauretta, Matthew V; Addis, Piero; Varela, Jose Luis; Fraile, Igaratza; Goñi, Nicolas; Abid, Noureddine; Alemany, Francisco; Oray, Isik K; Quattro, Joseph M; Sow, Fambaye N; Itoh, Tomoyuki; Karakulak, F Saadet; Pascual‐alayón, Pedro J; Santos, Miguel N; Tsukahara, Yohei; Lutcavage, Molly; Fromentin, Jean-marc; Arrizabalaga, Haritz.
Effective sustainable management of marine fisheries requires that assessed management units (that is, fish stocks) correspond to biological populations. This issue has long been discussed in the context of Atlantic bluefin tuna (ABFT, Thunnus thynnus) management, which currently considers two unmixed stocks but does not take into account how individuals born in each of the two main spawning grounds (Gulf of Mexico and Mediterranean Sea) mix in feeding aggregations throughout the Atlantic Ocean. Using thousands of genome‐wide molecular markers obtained from larvae and young of the year collected at the species’ main spawning grounds, we provide what is, to the best of our knowledge, the first direct genetic evidence for “natal homing” in ABFT. This has...
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Ano: 2019 URL: https://archimer.ifremer.fr/doc/00595/70710/68917.pdf
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Effect of minimum size regulations on east bluefin tuna (Thunnus thynnus L.) yield pe recruit ArchiMer
Restrepo, Victor; Arrizabalaga, Haritz; Ortiz De Urbina, J M; Fromentin, Jean-marc.
A standard yield per recruit (YPR) analysis is used to analyse the effects of minimum size regulations on bluefin tuna from the Eastern stock (East Atlantic and Mediterranean). Analyses were based on a selectivity vector computed over the period 1990- 1994 for which data were more reliable and VPA (performed during the 2002 stock assessment) showed a relatively good convergence. This selectivity vector was modified according to different minimum size regulations and implementation error levels. It is concluded that: (i) perfect implementation of the size limit regulation adopted in 2004 would increase YPR by 4.3% relative to the size limit adopted in 2002, and by 8.8% relative to the pattern realized in the early 1990s; (ii) YPR is however expected to...
Tipo: Text Palavras-chave: Yield/recruit; Yield predictions; Size limit regulations; Bluefin tuna..
Ano: 2006 URL: http://archimer.ifremer.fr/doc/00194/30545/28964.pdf
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Estimates of selectivity for eastern Atlantic bluefin tuna from catch curves ArchiMer
Restrepo, Victor R; Ortiz De Urbina, J; Fromentin, Jean-marc; Arrizabalaga, Haritz.
Knowledge of gear-specific selectivity patterns can be useful in age-structured analyses. In recent assessments of eastern Atlantic bluefin tuna, Thunnus thynnus, the SCRS has derived selectivity estimates from the results of virtual population analyses. This document proposes an alternative approach, based on equilibrium catch curves, that is simple to apply and that relies on a smaller set of assumptions. The study uses the catch-at-age data from the last assessment conducted in 2002, and estimates recent and historical selectivity patterns for the total stock as well as some of the major gears (trap, baitboat, purse seine and longline). The resulting estimates seem reasonable for the various gears, given prior knowledge. The document also presents...
Tipo: Text Palavras-chave: Gear selectivity; Stock assessment; Bluefin tuna.
Ano: 2007 URL: http://archimer.ifremer.fr/doc/00192/30326/28800.pdf
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Estimates of total mortality of eastern Atlantic bluefin tuna based on year-class curves ArchiMer
Fromentin, Jean-marc; Arrizabalaga, Haritz; Restrepo, Victor R; Ortiz De Urbina, J.
The 2004 data exploratory meeting concluded that it was no longer defensible to assess the East Atlantic and Mediterranean population using methods that assume that the catch-atsize/age is known exactly, until extensive improvements in fisheries statistics are made. For these reasons, we here investigated the potential benefits of the year-class curve analysis. The robustness and consistency of our results tend to advocate that this method is, in the present situation, a good alternative to ADAPT (among others). As a whole, the estimates of Z from the year-class curve analyses applied on the Spanish trap and Japanese long line fishery data appear indeed to be in good or excellent agreement with ADAPT outputs for the same period and same age-classes. This...
Tipo: Text Palavras-chave: Fishing and natural mortalities; Year-class curves; Stock assessment.
Ano: 2007 URL: http://archimer.ifremer.fr/doc/00192/30325/28799.pdf
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Global habitat preferences of commercially valuable tuna ArchiMer
Arrizabalaga, Haritz; Dufour, Florence; Kell, Laurence; Merino, Gorka; Ibaibarriaga, Leire; Chust, Guillem; Irigoien, Xabier; Santiago, Jose Luis; Murua, Hilario; Fraile, Igaratza; Chifflet, Marina; Goikoetxea, Nerea; Sagarminaga, Yolanda; Aumont, Olivier; Bopp, Laurent; Herrera, Miguel; Fromentin, Jean-marc; Bonhomeau, Sylvain.
In spite of its pivotal role in future implementations of the Ecosystem Approach to Fisheries Management, current knowledge about tuna habitat preferences remains fragmented and heterogeneous, because it relies mainly on regional or local studies that have used a variety of approaches making them difficult to combine. Therefore in this study we analyse data from six tuna species in the Pacific, Atlantic and Indian Oceans in order to provide a global, comparative perspective of habitat preferences. These data are longline catch per unit effort from 1958 to2007 for albacore, Atlantic bluefin, southern bluefin, bigeye, yellowfin and skipjack tunas. Both quotient analysis and Generalized Additive Models were used to determine habitat preference with respect to...
Tipo: Text Palavras-chave: Habitat; Tuna fisheries; Catch/effort; Environmental conditions; Quotient analysis; Generalised Additive Models; Ecosystem Approach to Fisheries Management.
Ano: 2015 URL: https://archimer.ifremer.fr/doc/00201/31190/29589.pdf
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Habitat suitability of the Atlantic bluefin tuna by size class: An ecological niche approach ArchiMer
Druon, Jean-noel; Fromentin, Jean-marc; Hanke, Alex R.; Arrizabalaga, Haritz; Damalas, Dimitrios; Ticina, Vjekoslav; Quilez-badia, Gemma; Ramirez, Karina; Arregui, Igor; Tserpes, George; Reglero, Patricia; Deflorio, Michele; Oray, Isik; Karakulak, F. Saadet; Megalbfonou, Persefoni; Ceyhan, Tevfik; Grubisic, Leon; Mackenzie, Brian R.; Lamkin, John; Afonso, Pedro; Addis, Piero.
An ecological niche modelling (ENM) approach was used to predict the potential feeding and spawning habitats of small (5-25kg, only feeding) and large (> 25kg) Atlantic bluefin tuna (ABFT), Thunnus thynnus, in the Mediterranean Sea, the North Atlantic and the Gulf of Mexico. The ENM was built bridging knowledge on ecological traits of ABFT (e.g. temperature tolerance, mobility, feeding and spawning strategy) with patterns of selected environmental variables (chlorophyll-a fronts and concentration, sea surface current and temperature, sea surface height anomaly) that were identified using an extensive set of precisely geo-located presence data. The results highlight a wider temperature tolerance for larger fish allowing them to feed in the northern –...
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Ano: 2016 URL: http://archimer.ifremer.fr/doc/00308/41953/41803.pdf
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Otolith shape variation provides a marker of stock origin for north Atlantic bluefin tuna (Thunnus thynnus) ArchiMer
Brophy, Deirdre; Haynes, Paula; Arrizabalaga, Haritz; Fraile, Igaratza; Fromentin, Jean-marc; Garibaldi, Fulvio; Katavic, Ivan; Tinti, Fausto; Karakulak, F. Saadet; Macias, David; Busawon, Dheeraj; Hanke, Alex; Kimoto, Ai; Sakai, Osamu; Deguara, Simeon; Abid, Nouredinne; Santos, Miguel Neves.
Two stocks of bluefin tuna (Thunnus thynnus) inhabit the north Atlantic; the western and eastern stocks spawn in the Gulf of Mexico and the Mediterranean Sea respectively. Trans-Atlantic movements occur outside spawning time whereas natal homing maintains stock structure. Commercial fisheries may exploit a mixed assemblage of both stocks. The incorporation of mixing rates into stock assessment is precluded by uncertainties surrounding stock discrimination. Otolith shape descriptors were used to characterise western and eastern stocks of Atlantic bluefin tuna in the present study and to estimate stock composition in catches of unknown origin. Otolith shape varied with length and between locations and years. Within a restricted size range (200-297-cm fork...
Tipo: Text Palavras-chave: Elliptical Fourier analysis; Population structure; Stock mixture analysis.
Ano: 2016 URL: http://archimer.ifremer.fr/doc/00346/45745/45381.pdf
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Standardized CPUE of bluefin tuna (Thunnus thynnus) caught by spanish traps for the period 1981-2004 ArchiMer
Ortiz De Urbina, J; Fromentin, Jean-marc; Restrepo, Victor R; Arrizabalaga, Haritz; De La Serna, Jose-miguel.
Catch rates from the Spanish traps in the Atlantic have been traditionally standardized using a GLM approach with a lognormal error assumption. Nevertheless, some concerns have been expressed regarding the current unit of effort used for standardization purposes as well as the model error assumption. This document explores the adequacy of current effort unit and proposes alternative model error assumptions for the standardization of the CPUE index.
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Ano: 2007 URL: http://archimer.ifremer.fr/doc/00192/30298/28788.pdf
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The spectre of uncertainty in management of exploited fish stocks: The illustrative case of Atlantic bluefin tuna ArchiMer
Fromentin, Jean-marc; Bonhommeau, Sylvain; Arrizabalaga, Haritz; Kell, Laurence T..
The recent overexploitation of East Atlantic and Mediterranean bluefin tuna stock has been well documented in the media where it has become the archetype of overfishing and general mis-management. Beyond the public debate, the crisis also highlighted how the interactions between science and management can change through time according to the awareness of the public opinion. To reflect these issues, the history of Atlantic bluefin tuna overfishing is first described. Then, the major uncertainties that undermine the current scientific advice are summarized and the importance of reducing their impacts by improving knowledge and developing robust scientific framework is considered. The study also discusses how uncertainty was used by different lobbies to...
Tipo: Text Palavras-chave: Overexploitation; Rebuilding; Uncertainty; Management; Scientific diagnosis; Tuna.
Ano: 2014 URL: http://archimer.ifremer.fr/doc/00177/28776/27302.pdf
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