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| Kell, Laurence T; Fromentin, Jean-marc. |
| Reference points are important elements of fisheries management and the supporting scientific advisory frameworks. However, fish stocks can fluctuate extensively over a large range of spatial and temporal scales independent of human exploitation and there has been a classical tendency to assume a dichotomy, i.e., that changes in fish populations are primarily attributable either to exploitation or to environmental variability. Therefore we look at variability in surplus production and examine the relative impacts of the environment and exploitation on the productivity of North Atlantic albacore (Thunnus alalunga). The analysis revealed that variations were driven by environmental effects. It was also found that substantial variations in time-series of... |
| Tipo: Text |
Palavras-chave: Thunnus alalunga; Albacore; Fisheries management; FLR; Reference points; Stationary processes; Surplus production.. |
| Ano: 2011 |
URL: http://archimer.ifremer.fr/doc/00192/30282/28758.pdf |
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| Imzilen, Taha; Bonhommeau, Sylvain; Rouyer, Tristan; Kell, Laurence T; Chassot, Emmanuel; Barde, Julien. |
| In this note, we present an approach which has been recently used to execute online the set of codes used for eastern blue_n tuna (BFT-E) stock assessment at ICCAT. We aim at discussing the possible interest of the approach to the IOTC Community for focusing on Indian ocean tuna and tuna-like stocks and running other assesment models such as Stock Synthesis 3 (SS3). In 2014, ICCAT BFT-E working group has been able to execute thousands of model runs by using parallelization of R and Fortran codes on a supercomputer. This approach has a lot of scienti_c bene_ts, in particular for better including the multiple sources of uncertainty in assessment results and associated scienti_c advice. However, very few participants would be able to reproduce it without... |
| Tipo: Text |
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| Ano: 2016 |
URL: http://archimer.ifremer.fr/doc/00360/47135/47084.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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| Kell, Laurence T; Fromentin, Jean-marc; Gauthiez, F; Restrepo, Victor. |
| The Ad Hoc Working Group on the Precautionary Approach (SCRS/99/11) recommended the development of a simulation modelling framework to investigate the performance of stock specific management strategies under a variety of realistic hypothesis about population and fishery dynamics. This paper describes a preliminary simulation model based on East Atlantic bluefin tuna developed using flexible software that allows the implications for management of a variety of plausible hypotheses about stock and fishery dynamics to be explored. The intention is to illustrate the ways in which such models can be used and the types of advice that they can provide |
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| Ano: 2000 |
URL: http://archimer.ifremer.fr/doc/00194/30566/28991.pdf |
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