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| Registros recuperados: 27 | |
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| Fromentin, Jean-marc. |
| Since 2007, Ifremer together with the French Federation of Sport fishermen (FFPM) and Big Game Fishing Club France (BGFCF) have been carrying out a program of conventional and electronic tagging on bluefin tuna in the western Mediterranean Sea. 479 and 95 ICCAT “spaghetti” tags have been deployed by the FFPM recreational and sportive fishermen along the Mediterranean French coasts in 2007 and 2008, respectively. To date, not a single recapture has been registered. Ifremer together with BGFCF has deployed 11, 6 and 8 pop-up archival tags (PAT) offshore of Marseille in 2007, 2008 and 2009, respectively. Outputs were impaired by two main technical difficulties: premature detachment and low transmission rates in the Argos band over the Mediterranean. While... |
| Tipo: Text |
Palavras-chave: Thunnus thynnus; Tagging; Mediterranean Sea; Pop-up archival tag; Conventional tag. |
| Ano: 2010 |
URL: http://archimer.ifremer.fr/doc/00192/30291/28770.pdf |
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| Royer, Francois; Fromentin, Jean-marc. |
| This paper provides an exploratory analysis aiming to seek whether the colour of environmental noise theory could help in understanding the intriguing reproductive strategy of Atlantic bluefin tuna (BFT). A frequency-based approach based on spectral exponents, f(beta) with beta < 0, is chosen and applied on 10 biogeographical provinces covering the North Atlantic. The major BFT spawning area, i.e. the Mediterranean Sea, was the only one to display a pink power spectrum, whereas open ocean regions displayed more reddened fluctuations, i.e. greater variance at low frequencies. Environmental noise in the Mediterranean could, thus, offer more favourable characteristics on the long-term than the open ocean. The implications of these findings are discussed in... |
| Tipo: Text |
Palavras-chave: Thunnus thynnus; Spectral analysis; Spawning; Sea surface temperature; Environmental noise. |
| Ano: 2007 |
URL: http://archimer.ifremer.fr/doc/2007/publication-2437.pdf |
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| Fromentin, Jean-marc; Restrepo, Victor. |
| At the ICCAT symposium on bluefin tuna that held in Santander in April 2008, Tangen et al.(2009) presented a first quantification of the fishing effort deployed by the Norwegian fishery targeting bluefin tuna in the North Sea and Norwegian Sea. Using a year-class curve analysis on the Norwegian CPUE, this document presents the first estimates of mortality rates of Atlantic bluefin tuna that migrated north from the mid-1950s to the late 1970s. The results indicate that bluefin tuna would have experienced a total mortality rate (Z) of 0.2 to 0.4 yr-1 (i.e. F at around 0.3 yr-1) during the late 1950s, 0.2 yr-1 during the 1960s and 0.1 yr-1 afterwards (assuming M=0.1 yr-1). These results appear to be rather robust and consistent with the VPA estimates from the... |
| Tipo: Text |
Palavras-chave: Thunnus thynnus; Fishing and natural mortalities; Year-class curves; Stock assessment. |
| Ano: 2009 |
URL: http://archimer.ifremer.fr/doc/00192/30294/28783.pdf |
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| Bauer, Robert; Bonhommeau, Sylvain; Brisset, Blandine; Fromentin, Jean-marc. |
| Conservation and management measures for exploited fish species rely on our ability to monitor variations in population abundance. In the case of the eastern stock of Atlantic bluefin tuna (ABFT), recent changes in management policies have strongly affected the reliability of fishery-dependent indicators due to drastic changes in fishing season/area, fisheries selectivity and strategy. However, fishery-independent indices of abundance are rare for large pelagic fish, and obtaining them is often costly and labor intensive. Here, we show that scientific aerial surveys are an appropriate tool for monitoring juvenile bluefin tuna abundance in the Mediterranean. We present an abundance index based on 62 aerial surveys conducted since 2000, using 2 statistical... |
| Tipo: Text |
Palavras-chave: Thunnus thynnus; Index of abundance; Fishery-independent; Gulf of Lions; Mediterranean Sea; Strip transect; Distance sampling. |
| Ano: 2015 |
URL: https://archimer.ifremer.fr/doc/00281/39192/45096.pdf |
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| Bauer, Robert Klaus; Fromentin, Jean-marc; Demarcq, Herve; Bonhommeau, Sylvain. |
| We investigated the habitat utilization, vertical and horizontal behaviour of Atlantic bluefin tuna Thunnus thynnus (ABFT) in relation to oceanographic conditions in the northwestern Mediterranean Sea, based on 36 pop-up archival tags and different environmental data sets. Tags were deployed on early mature ABFT (127–255 cm) between July and November in 2007-2014, on the shelf area off Marseille, France. The data obtained from these tags provided 1643 daily summaries of ABFT vertical behaviour over 8 years of tag deployment. Based on a hierarchical clustering of this data, we could identify four principle daily vertical behaviour types, representing surface (≦10m) and subsurface (10–100 m) orientation, moderate (50–200 m) and deep (≧200m) diving behaviour.... |
| Tipo: Text |
Palavras-chave: Thunnus thynnus; Habitat use; Spike dives; Fronts; Thermal stratification; Archival tags. |
| Ano: 2017 |
URL: http://archimer.ifremer.fr/doc/00382/49329/49709.pdf |
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| Fromentin, Jean-marc. |
| In 1963, the leading fisheries targeting Atlantic bluefin tuna (Thunnus thynnus) in the Norwegian Sea and North Sea suddenly collapsed without any warning. Little is known about this collapse and several hypotheses have been put forward, such as changes in migratory routes, recruitment failure or eradication of a sub-population: all of these hypotheses could result from natural causes and/or from overfishing. To help explain this mysterious event, an original data set of the main bluefin tuna fisheries of the 20th century, including total catch and size composition of the catch, has been compiled and analysed. The results reveal a strong and unambiguous link between the Nordic purse seine and Spanish trap fisheries during the 1950s and 1960s. However, this... |
| Tipo: Text |
Palavras-chave: Thunnus thynnus; Retrospective analysis; Population structure; Migration patterns; Fisheries collapse. |
| Ano: 2009 |
URL: http://archimer.ifremer.fr/doc/2009/publication-6425.pdf |
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| Fromentin, Jean-marc; Kell, Laurence T. |
| An integrative simulation framework was built to evaluate the consequences of variability attributable to changes in carrying capacity or the stock’s migration pattern of Atlantic bluefin tuna on the ICCAT stock assessment and management procedures. We also evaluated the performances of stock assessment methods with respect to their ability to provide good estimates of MSY, FMSY and BMSY and tested the robustness of the current ICCAT management strategy to uncertainty about the true dynamics and historical exploitation levels. The results clearly indicate that the VPA performances were seriously impaired if the long-term variations in catches are due to changes in migration/availability. There is further considerable confounding between the underlying... |
| Tipo: Text |
Palavras-chave: Thunnus thynnus; Stock assessment; VPA; Biological reference points; MSY; Management strategy; Simulation model. |
| Ano: 2009 |
URL: http://archimer.ifremer.fr/doc/00192/30295/28786.pdf |
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| Fromentin, Jean-marc. |
| The present paper proposes a simple descriptive analysis of the ICCAT bluefin tuna tagging database. Since 1954, about 91.2% of the tags were released in the West Atlantic and 8.8% in the East Atlantic. The great majority of tags was recaptured in their area of release, i.e., 95.7% and 97.25% for the East and the West Atlantic, respectively. The number of tags released in the West and recaptured in the East (102) was about 5 times higher than the reverse (19), but the percentage of transatlantic migrations from East-to-West (4.3%) was about 2 times higher than the one from West-to-East (2.25%). The percentage of transatlantic migrations varies over time, especially from West-to-East. It was much higher during the 90’s (7.6%) than in the three previous... |
| Tipo: Text |
Palavras-chave: Conventional tag; Migration rates; Thunnus thynnus; East and West Atlantic stocks. |
| Ano: 2002 |
URL: http://archimer.ifremer.fr/doc/00194/30495/28904.pdf |
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| Fromentin, Jean-marc; Lopuszanski, Daniel. |
| This study presents the results of an electronic tagging programme on mature Atlantic bluefin tuna (ABFT) that has been conducted since 2007 offshore of the French Mediterranean Coast. The spatial distributions of ABFT showed little year-to-year variation and the fish concentrated in a small area of the central northwestern Mediterranean, where they may stay for several months. The individual tracks display sinuous trajectories in this area, indicating the possibility of feeding behaviour. No fish went out to the North Atlantic, but several fish displayed some migration to the southern western Mediterranean Sea during winter and the central Mediterranean during the spawning season. The homing behaviour of one fish after a full year as well as the back and... |
| Tipo: Text |
Palavras-chave: Feeding area; Front; Marine protected area; Pop-up archival tag; Spatial distribution; Thunnus thynnus. |
| Ano: 2014 |
URL: http://archimer.ifremer.fr/doc/00165/27637/25835.pdf |
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| Fromentin, Jean-marc. |
| The aim of this study is to investigate the implications of different stock-recruitment assumptions when examining the potential of Dubrovnik’s bluefin tuna recovery plan. To do so, some Beverton and Holt relationships displaying contrasting steepness of 0.99, 0.90, 0.75 and 0.50 were applied within a simulation model. In addition to these four stock-recruitment scenarios, parental effects and stochastic variations were also considered. The main conclusion is that our ability to evaluate the consequences of the Dubrovnik agreement (as any set of management measures) relies on our capacity to predict future recruitment levels in an accurate way. Assuming a Beverton and Holt relationship with different steepness, with or without parental effects and with or... |
| Tipo: Text |
Palavras-chave: Thunnus thynnus; Management regulations; Stock-recruitment; Parental effects; Stock rebuilding; Simulation model. |
| Ano: 2009 |
URL: http://archimer.ifremer.fr/doc/00192/30296/28784.pdf |
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| Gatesoupe, Joel; Coves, Denis; Ortega, Aurelio; Papandroulakis, Nikos; Vadstein, Olav; De La Gandara, Fernando. |
| During the first 2 years of larval rearing trials with Atlantic bluefin tuna, survival was a challenging issue. As bacterial colonization of the gut has been shown to play a key role for other species, we studied the profiles of the microbiota associated with individual larvae at different stages in three distant hatcheries. The Bacterial Community Profile (BCP) was quantified based on PCR-DGGE analyses of partial amplicons from 16S rDNA. Considerable individual variability in BCP was observed before onset of feeding, and the BCP did not show regular fluctuation during ontogenesis. Microalgae were added to the rearing tanks in two of the three hatcheries, but it was not possible to distinguish the effect of location from the effect of algal addition on... |
| Tipo: Text |
Palavras-chave: Larval rearing; Bacterial diversity; DGGE; Thunnus thynnus. |
| Ano: 2013 |
URL: http://archimer.ifremer.fr/doc/00075/18648/16197.pdf |
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| Ravier-mailly, Christelle; Fromentin, Jean-marc. |
| We tested whether synchronous long-term fluctuations in Atlantic bluefin tuna (Thunnus thynnus) trap catches, collected from the ancestral Mediterranean and Atlantic trap fishery, might be related to environmental changes in NAO and/or in temperature. Spectral analyses of trap catches and temperature displayed similar spectra with peak at low frequency whereas those of the NAO exhibited a broad band spectrum. Regression analyses and tests of correlation did not reveal any clear relationship between trap catches and NAO. In contrast, long-term fluctuations in trap catches appear to be negatively and significantly related to long-term trends in temperature. Underlying processes that could explain such a relationship are discussed, with special focus on... |
| Tipo: Text |
Palavras-chave: Thunnus thynnus; NAO; Temperature; Trap fishery; Migration. |
| Ano: 2003 |
URL: http://archimer.ifremer.fr/doc/00194/30530/28940.pdf |
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| Ravier, Christelle; Fromentin, Jean-marc. |
| More than one hundred long-term time-series of bluefin tuna catches from the ancestral Mediterranean and Atlantic trap fisheries are used to (1) estimate historical range of BFT yields in the Mediterranean and adjacent Atlantic and (2) investigate spatial and temporal patterns of fluctuations in trap catches. Mean historical catches were around 110 000 tunas/year (± 50 000), i.e. 15 000 tons/year (∈[7 000;25 000]). Fluctuations in trap catches are of large magnitude, periods of high abundance being up to seven times higher than those of low abundance. More interesting was the occurrence of 100-year-long periodic fluctuations as well as 20-year cycles. These medium- to long-term fluctuations, representing more than 50% of the total variability in the... |
| Tipo: Text |
Palavras-chave: Thunnus thynnus; Time series analyses; Abundance; Population dynamics; Long-term changes; Trapfishing. |
| Ano: 2002 |
URL: http://archimer.ifremer.fr/doc/00194/30497/28906.pdf |
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| Registros recuperados: 27 | |
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