Fish biomass estimates along estuaries: A comparison of vertical acoustic sampling at fixed stations and purse seine catches

Jean Guillard 1 Monique Simier 2 Jean-Jacques Albaret 3 Jean Raffray 4 Idrissa Sow 5 Luis Tito de Morais 4
1 CARRTEL - Centre Alpin de Recherche sur les Réseaux Trophiques et Ecosystèmes Limniques
2 EME - UMR 212 EME "écosystèmes marins exploités"
3 RAP - Réponses adaptatives des populations et des peuplements de poissons aux pressions de l'environnement
4 LEMAR - Laboratoire des Sciences de l'Environnement Marin (LEMAR)
5 CRODT
Abstract : Two techniques, the conventional purse seine method and a novel method using vertical hydroacoustic surveys at fixed positions, were applied simultaneously in the Gambia River estuary to sample a fish population. Environmental parameters were measured simultaneously. Four surveys were performed during different hydrological seasons to reflect the main sources of variation in the environmental conditions of the estuary. A total of 153 samples resulted from these surveys. To identify the environmental conditions in which the two methods yield similar pictures of the fish population, a regression tree was constructed in which the dependent variable was the difference between the standardised values of the catches from the purse seine and the estimated biomass from the acoustic samples. A highly significant correlation was found between the two approaches using a set of data (128 samples) that excluded the samples with specific environmental conditions (downstream samples with high transparency, and upstream ones with high transparency, high depth and high temperature). We conclude that, except under these specific environmental conditions, vertical hydroacoustic samples recorded at a fixed station can serve as a proxy of the catches from a purse seine and can allow the monitoring of fish biomass in estuaries without damaging the environment.
Keywords : estuary purse seine hydroacoustic fish West Africa the Gambia River
Type de document :
Article dans une revue
Estuarine, Coastal and Shelf Science, Elsevier, 2012, 107, pp.105-111. 〈10.1016/j.ecss.2012.05.022〉
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Soumis le : jeudi 14 février 2013 - 17:34:42
Dernière modification le : jeudi 11 janvier 2018 - 06:22:24

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Jean Guillard, Monique Simier, Jean-Jacques Albaret, Jean Raffray, Idrissa Sow, et al.. Fish biomass estimates along estuaries: A comparison of vertical acoustic sampling at fixed stations and purse seine catches. Estuarine, Coastal and Shelf Science, Elsevier, 2012, 107, pp.105-111. 〈10.1016/j.ecss.2012.05.022〉. 〈hal-00788623〉

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