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Spatio-temporal variability of fish assemblages in the Gambia Estuary (West Africa) observed by two vertical hydroacoustic methods: Moored and mobile sampling

Published online by Cambridge University Press:  15 March 2004

Jean Guillard ,
Jean-Jacques Albaret ,
Monique Simier ,
Ibrahima Sow ,
Jean Raffray  and
Luis Tito de Morais
Jean Guillard*
Affiliation:
IRD, Centre de Recherche Halieutique Méditerranéenne et Tropicale, BP 171, 34203 Sète Cedex, France INRA, Station Hydrobiologie Lacustre, UMR CARRTEL, BP 511, 74203 Thonon les bains, France
Jean-Jacques Albaret
Affiliation:
IRD, Centre IRD de Dakar, UR070, BP 1386, Dakar, Sénégal
Monique Simier
Affiliation:
IRD, Centre de Recherche Halieutique Méditerranéenne et Tropicale, BP 171, 34203 Sète Cedex, France
Ibrahima Sow
Affiliation:
CRODT, BP 2241, Dakar, Sénégal
Jean Raffray
Affiliation:
IRD, Centre IRD de Dakar, UR070, BP 1386, Dakar, Sénégal
Luis Tito de Morais
Affiliation:
IRD, Centre IRD de Dakar, UR070, BP 1386, Dakar, Sénégal
*
[email protected]
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Abstract

The Gambia Estuary is one of the last estuaries in West Africa not to have been affected by strong environmental changes and adverse human disturbances. In order to describe the spatio-temporal change in fish biomass in this estuary, and the seasonal changes in fish size classes, five research surveys have been conducted at characteristic periods in the river's water regime and meteorological seasons. The fish assemblages were sampled by two vertical echosounding protocols: mobile surveys (zigzag transects) in the estuary and moored stations. The two sampling methods produced a similar image of the fish assemblages in terms of the distribution of total biomass and target strength distributions. Large fish aggregations were detected in the most marine area at the end of the wet season, and fish biomass increased through the dry season in the upstream zone. Fish were smaller at the beginning of the wet season and they were always larger in downstream areas.

Keywords

Hydro-acousticVertical soundingSplit-beamFishEstuaryGambiaWest Africa
Type
Research Article
Information
Aquatic Living Resources , Volume 17 , Issue 1 , January 2004 , pp. 47 - 55
Copyright
© EDP Sciences, IFREMER, IRD, 2004

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References

Albaret J.J., 1999, Les peuplements des estuaires et des lagunes. In: Lévêque C., Paugy D. (Eds.) Les poissons des eaux continentales africaines : diversité, écologie, utilisation par l'homme. IRD, Paris, pp. 325-349.
Albaret, J.J., Simier, M., Darboe, F.S., Ecoutin, J.M., Raffray, J., Tito de Morais, L., 2004, Fish diversity and distribution in the Gambia Estuary, West Africa, in relation to environmental variables. Aquat. Living Resour. 17, 35-46. CrossRef
Belliard, J., Boët, P., Tales, E., 1997, Regional and longitudinal patterns of fish community structure in the Seine River basin, France. Environ. Biol. Fish. 50, 133-147. CrossRef
Borgmann, U., 1987, Models on the slope of, and biomass flow up, the biomass spectrum. Can. J. Fish. Aquat. Sci. 44, 136-140. CrossRef
Brandt S.B., 1996, Acoustic assessment of fish abundance and distribution. In: Murphy B.R. Willis D.W. (Eds.) Fisheries Techniques, 2nd edition. Am. Fish. Soc. pp. 385-432.
Brehmer, P., Gerlotto, F., Guillard, J., Sanguinède, F., Guennégan, Y., Buestel, D., 2003, New applications of under-acoustics methods for monitoring shallow water aquatic ecosystems: the case of mussel culture grounds in open sea. Aquat. Living Resour. 16, 333-338. CrossRef
Cottingham, K.L., Brown, B.L., Lennon, J.T., 2001, Biodiversity may regulate the temporal variability of ecological systems. Ecol. Lett. 4, 72-85. CrossRef
Cowx I.G., 1996, Stock assessment in inland fisheries. Fishing News Books, Blackwell Sci. Publ., London.
Daget J., 1960, La faune ichtyologique du bassin de la Gambie. Bull. Inst. Fr. Afr. N., 22, 611-619.
Debruyn, A.M.H., Marcogliese, D.J., Rasmussen, J.B., 2002, Regional analysis of body size and population density in stream fish assemblages: testing predictions of the energetic equivalence rule. Can. J. Fish. Aquat. Sci. 59, 819-828. CrossRef
Dorr J.A.III, Schneeberger P.J., Tin H.T., Flath L.E., 1985, Studies on adult, juvenile and larval fishes of the Gambia river, West Africa, 1983-1984, Report n° 11, Great Lakes and Marine Waters Center international programs, The University of Michigan, Ann Arbor, Michigan.
Duncan, A., Butterworth, A.J., Gerlotto, F., Kubecka, J., 1998, Editorial. Fish. Res. 35, 1-3.
Foote K.G., Knudsen H., Vestnes G. 1987, Calibration of acoustic instruments for fish density estimation: a practical guide. ICES Coop. Res. Rep. 144.
Frear, P.A., 2002, Hydroacoustic target strength validation using angling creel census data. Fish. Manage. Ecol. 9, 343-350. CrossRef
Fréon P., Misund O.A., 1999, Dynamics of pelagic fish distribution and behaviour: effects on fisheries and stock assessment. Fishing News Books, Blackwell Science, Oxford.
Fréon, P, Dagorn, L., 2000, Review of fish associative behaviour: toward a generalisation of the meeting point hypothesis. Rev. Fish Biol. Fish. 10, 183-207. CrossRef
Gerlotto, F., Soria, M., Fréon, P., 1999, From two dimensions to three: the use of multibeam sonar for a new approach in fisheries acoustics. Can. J. Fish. Aquat. Sci. 56, 6-12. CrossRef
Guillard, J., 1998, Daily migration cycles of fish populations in a tropical estuary (Sine-Saloum, Senegal) using a horizontal-directed split-beam transducer and multibeam sonar. Fish. Res. 35, 21-29. CrossRef
Guillard, J., Boet, P., Gerdeaux, D, Roux, P., 1994, Application of mobile acoustic techniques fish survey in shallow waters: the river Seine. Regul. Rivers 9, 121-126. CrossRef
Harvey J., Cowx I.G., 1996, Electric fishing for assessment of fish stocks in large rivers. In: Cowx I.G. (Ed.) Stock Assessment in Inland Fisheries. Fishing News Books, Blackwell Science, Oxford, pp. 11-26.
Hughes, S., 1998, A mobile horizontal hydroacoustic fisheries survey of the River Thames, United Kingdom. Fish. Res. 35, 91-97. CrossRef
Jorgensen, R. Olsen, K., 2002, Acoustic target strength of capelin measured by single-target tracking in a controlled cage experiment. ICES J. Mar. Sci. 59, 1081-1085. CrossRef
Knudsen F.R. Sægrov H., 2002, Benefits from horizontal beaming during acoustic survey: application to three Norwegian lakes. Fish. Res. 56, 205-211.
Krumme, U., Saint-Paul, U., 2003, Observations of fish migration in a macrotidal mangrove channel in Northern Brazil using a 200 kHz split-beam sounder. Aquat. Living Resour. 16, 175-184. CrossRef
Kubecka, J., Duncan, A., 1998, Acoustic size vs. real size relationships for common species of riverine fish. Fish. Res. 35, 115-125. CrossRef
Kubecka J., Frouzova J., Vilcinskas A., Wolter C., Slavik O., 2000, longitudinal hydroacoustic survey of fish in the Elbe River supplemented by dircet capture. In: Cowx I.G. (Ed.) Stock Assessment in Inland Fisheries. Fishing News Books, Blackwell Science, Oxford, pp. 14-26.
Kubecka, J., Wittingerova, M., 1998, Horizontal beaming as a crucial component of acoustic fish stock assessment in freshwater reservoirs. Fish. Res. 35, 99–106. CrossRef
Laë, R., Ecoutin, J.M., Mendy, A., Raffray, J., Weigel, J.Y., Sadio, O., Djobe, O., 2004, Effects of a targeted shrimp (Penaeus notialis) exploitation on fish catches in the Gambia estuary. Aquat. Living Resour. 17, 75-85. CrossRef
Lesack, L.F.W., 1986, Estimates of catch and potential yield for riverine artisanal fishery in The Gambia, West Africa. J. Fish Biol. 28, 679-700. CrossRef
Lesack, L.F.W., Hecky, R.E., Melack, J.M., 1984, Transport of carbon, nitrogen, phosphorus and major solutes in the Gambia River, West Africa. Limnol. Oceanogr. 29, 816-830. CrossRef
Love, R.H., 1977, Target strength of an individual fish at any aspect. J. Acoust. Soc. Am. 72, 1397-1402. CrossRef
Lilja, J., Keskinen, T., Marjomäki, T.J., Valkeajärvi, P., Karjalainen, J., 2003, Upstream migration activity of cyprinids and percids in a channel, monitored by a horizontal split-beam echosounder. Aquat. Living Resour. 16, 185-190. CrossRef
Lyons, J., 1998, A hydroacoustic assessment of fish stocks in the River Trent, England. Fish. Res. 35, 83-90. CrossRef
MacLennan, D., Fernandes, P.G., Dalen, J., 2002, A consistent approach to definitions and symbols in fisheries acoustics. ICES J. Mar. Sci. 59, 365-369. CrossRef
MacLennan D.N., Simmonds E.J., 1992, Fisheries acoustics, Chapman and Hall, New York.
Mouse P.J., Kemper J., 1996, Applications of a hydroacoustic sampling technique in a large wind-exposed shallow lake. In: Cowx I.G. (Ed.) Stock Assessment in Inland Fisheries. Fishing News Books, Blackwell Science, Oxford, pp. 179-195.
Mulligan, T., 2000, Shallow water fisheries sonar: a personal view. Aquat. Living Resour. 13, 269-273. CrossRef
Schramm, H.L., Grado, S.C., Pugh, L.L., 2001, The costs of sampling fishes in riverine habitats of a large river. Fish. Res. 56, 51-57. CrossRef
Sprent P., 1992, Pratique des statistiques non paramétriques. INRA Paris.
Thorne, D., 1998, Review: experiences with shallow water acoustics. Fish. Res. 35, 137-142. CrossRef
Trevorrow, M., Burczynski, J., Kubecka, J., 2000, Editorial. Aquat. Living Resour. 13, 267. CrossRef
Vidy, G., Darboe, F.S., Mbye, E.M., 2004, Juvenile fish assemblages in the creeks of the Gambia estuary. Aquat. Living Resour. 17, 56-64. CrossRef