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| Mollet, Fabian M.; Ernande, Bruno; Brunel, Thomas; Rijnsdorp, Adriaan D.. |
| We present a new methodology to estimate rates of energy acquisition, maintenance, reproductive investment and the onset of maturation (four-trait estimation) by fitting an energy allocation model to individual growth trajectories. The accuracy and precision of the method is evaluated on simulated growth trajectories. In the deterministic case, all life history parameters are well estimated with negligible bias over realistic parameter ranges. Adding environmental variability reduces precision, causes the maintenance and reproductive investment to be confounded with a negative error correlation, and tends, if strong, to result in an underestimation of the energy acquisition and maintenance and an overestimation of the age and size at the onset of... |
| Tipo: Text |
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| Ano: 2010 |
URL: http://archimer.ifremer.fr/doc/2010/publication-7386.pdf |
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| Brunel, Thomas; Ernande, Bruno; Mollet, Fabian M.; Rijnsdorp, Adriaan D.. |
| A new method is presented to estimate individuals’ (1) age at maturation, (2) energy acquisition rate, (3) energy expenditure for body maintenance, and (4) reproductive investment, and the multivariate distribution of these traits in a population. The method relies on adjusting a conceptual energy allocation model to individual growth curves using nonlinear mixed-effects modelling. The method’s performance was tested using simulated growth curves for a range of life-history types. Individual age at maturation, energy acquisition rate and the sum of maintenance and reproductive investment rates, and their multivariate distribution, were accurately estimated. For the estimation of maintenance and reproductive investment rates separately, biases were observed... |
| Tipo: Text |
Palavras-chave: Bioenergetics growth model; Individual growth trajectory; Life-history trade-offs; Energy acquisition; Maintenance; Reproductive investment; Sexual maturation. |
| Ano: 2013 |
URL: http://archimer.ifremer.fr/doc/00124/23537/21378.pdf |
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| Brunel, Thomas; Boucher, Jean. |
| Synchrony in population fluctuations have commonly been observed among a variety of species. They are generally attributed to the effect of common environmental forcings on population dynamics. Here, we investigate long term synchrony in the recruitment variations of the North East Atlantic fish populations. A PCA (principal component analysis) was performed to extract the main patterns of variation. The most significant one reflects the synchronous decrease of the recruitment for the majority of gadoids populations, in the Baltic Sea, Kattegat, North Sea, Irish Sea and West of Scotland. The inverse pattern was observed for half of the herring populations. Plaice populations also exhibit synchronous recruitment trends, characterised by strong year classes... |
| Tipo: Text |
Palavras-chave: Synchrony; Regime shift; Recruitment variations; North Eastern Atlantic; Climate change. |
| Ano: 2004 |
URL: http://archimer.ifremer.fr/doc/2004/acte-1145.pdf |
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| Brunel, Thomas; Boucher, Jean. |
| This study investigates the temporal correspondence between the main patterns of recruitment variations among north-east Atlantic exploited fish populations and large-scale climate and temperature indices. It is of primary importance to know what changes in fish stock productivity can be expected in response to climate change, to design appropriate management strategies. The dominant patterns of recruitment variation were extracted using a standardized principal component analysis (PCA). The first principal component (PC) was a long-term decline, with a stepwise change occurring in 1987. A majority of Baltic Sea, North Sea, west of Scotland and Irish Sea populations, especially the gadoids, have followed this decreasing trend. On the contrary, some herring... |
| Tipo: Text |
Palavras-chave: North Atlantic; Global warming; Fishing impacts; Fish recruitment; Comparative approach; Climate change. |
| Ano: 2007 |
URL: http://archimer.ifremer.fr/doc/2007/publication-2636.pdf |
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| Ulrich, Clara; Vermard, Youen; Dolder, Paul J.; Brunel, Thomas; Jardim, Ernesto; Holmes, Steven J.; Kempf, Alexander; Mortensen, Lars O.; Poos, Jan-jaap; Rindorf, Anna. |
| Achieving single species maximum sustainable yield (MSY) in complex and dynamic fisheries targeting multiple species (mixed fisheries) is challenging because achieving the objective for one species may mean missing the objective for another. The North Sea mixed fisheries are a representative example of an issue that is generic across most demersal fisheries worldwide, with the diversity of species and fisheries inducing numerous biological and technical interactions. Building on a rich knowledge base for the understanding and quantification of these interactions, new approaches have emerged. Recent paths towards operationalizing MSY at the regional scale have suggested the expansion of the concept into a desirable area of “pretty good yield”, implemented... |
| Tipo: Text |
Palavras-chave: Choke species; Common Fisheries Policy; Fleet modelling; FMSY ranges; Landing obligation; Management plan; Pretty good yield. |
| Ano: 2017 |
URL: https://archimer.ifremer.fr/doc/00347/45834/45922.pdf |
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| Brunel, Thomas; Boucher, Jean. |
| It has long been argued that populations living on the edges of the species geographical range should exhibit stronger environmentally imposed variations in abundances than populations living near the centre of this range. This so-called 'Species Range Hypothesis' is tested here for the recruitment of 62 marine fish populations of the northeast Atlantic, belonging to 17 species. The pattern of increasing recruitment variability from the centre towards the edges of the species range was modelled by a quadratic linear regression between an index of interannual variability in recruitment and an index of population position in species range. The relationship between recruitment variability and exploitation rate was also investigated. A wide range of... |
| Tipo: Text |
Palavras-chave: Environment; Comparative approach; Northeast Atlantic; Species range hypothesis; Recruitment variability. |
| Ano: 2006 |
URL: http://archimer.ifremer.fr/doc/2006/publication-1119.pdf |
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