Hostname: page-component-cd9895bd7-jn8rn Total loading time: 0 Render date: 2024-12-19T01:43:57.787Z Has data issue: false hasContentIssue false
  • English
  • Français

The use of biological indicators for monitoring fisheries exploitation: Application to man-made reservoirs in Mali

Published online by Cambridge University Press:  15 June 2004

Raymond Laë ,
Jean-Marc Ecoutin  and
Justin Kantoussan
Raymond Laë
Affiliation:
IRD Bel Air, BP 1386, Dakar, Senegal
Jean-Marc Ecoutin
Affiliation:
IRD Bel Air, BP 1386, Dakar, Senegal
Justin Kantoussan
Affiliation:
IRD Bel Air, BP 1386, Dakar, Senegal
Get access

Abstract

A comparative study, using biological indicators, was conducted in Mali where two man-made reservoirs (Selengue and Manantali) are particularly suited for investigating the impact of fishing effort on the fish assemblage: these two ecosystems have relatively similar morphological, edaphic and environmental properties but are subjected to radically different levels of fishing exploitation (low at Manantali, high at Selengue). The comparison is based on a three-month survey of commercial fisheries, focusing on fishing activities and catches on the two reservoirs.

The results show that some indicators are useful for evaluating fishing impacts. Among these indicators are: fishing effort which is much higher at Selengue (22 800 fishing trips per month) than at Manantali (3000), catches per unit effort (lower at Selengue than at Manantali following a ratio ranging from 1.5 to 4 according to the gears used), annual yields per ha higher at Selengue (100 kg ha−1) than at Manantali (27 kg ha−1), the average fish lengths in the catches (16.2 cm at Selengue compared to 23.6 cm at Manantali) and the maximum lengths of the targeted species generally smaller at Selengue (10 to 30 cm) than at Manantali (30 to 50 cm). By contrast, a second class of indicators exhibit values that are contrary to expectations: the species richness (52 compared to 36), the species diversity (I sh = 4.02 compared to 3.24) and evenness (0.76 compared to 0.69) were higher at Selengue where 4 species accounted for 50% of the landings compared to only 2 species at Manantali (9 species compared to 7 for 80% of the landings). The trophic structure of the landings is higher (37% primary consumers compared to 49% at Manantali) as well as the mean trophic level (2.74 compared to 2.54 at Manantali).

Even if a good understanding of the two fisheries can explain the unexpected trends of the second class of indicators which increase with fishing effort, it clearly appears from this study that only the first class of indicators is robust and can be used for comparative studies across ecosystems.

Keywords

Fish populationsFishing effortDiversityYieldMean lengthTrophic levelWest Africa
Type
Research Article
Information
Aquatic Living Resources , Volume 17 , Issue 2 , April 2004 , pp. 95 - 105
Copyright
© EDP Sciences, IFREMER, IRD, 2004

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

Adams S.M. (Ed.) 2002, Biological indicators of aquatic ecosystem stress. Amer. Fish. Soc. Bethesda, Maryland.
Adams S.M., Greeley M.S., 2000, Ecotoxicological indicators of water quality: using multi-responses indicators to assess the health of aquatic ecosystems. Water, Air Soil Pollut. 123, 103-115.
Alhousseini S., 1999, Peuplement ichtyologique et exploitation des espèces d'intérêt halieutique de la retenue d'eau de Manantali (Mali). Thèse Université de Provence, France.
Alhousseini S., Kassibo B., 2000, La pêche à Manantali : le milieu, les hommes, les stratégies d'exploitation et de valorisation des ressources halieutiques. In: Bonavita D. (Ed.), Manantali entre espoir et désillution, Édition Le Figuier, Bamako, Mali, pp. 151-211.
Arfi R., 2003, Effects of climate and hydrology on the trophic status of Sélingué reservoir (Mali, West Africa). Lakes Reservoir Research Management 8, in press.
Bianchi, G., Gislason, H., Graham, K., Hill, S., Jin, X., Koranteng, K., Manickchand-Heileman, S., Paya, I., Sainsbury, K., Sanchez, F., Zwanenburg, K., 2000, Impact of fishing on size composition and diversity of demersal fish communities. ICES J. Mar. Sci. 57, 558-571. CrossRef
Blaber, S.J.M., Cyrus, D.P., Albaret, J.J., Chong Ving Ching Day, J.W., Elliott, M., Fonseca, M.S., Hoss, D.E., Orensanz, J., Potter, I.C., Silvert, W., 2000, Effects of fishing on the structure and functioning of estuarine and nearshore ecosystems. ICES J. Mar. Sci. 57, 590-602. CrossRef
Bowman, R.E., 1986, Effect of regurgitation on stomach content data of marine fisheries. Environ. Biol. Fish. 16, 171-181. CrossRef
Buckworth, R.C., 1998, World fisheries are in crisis? We must respond! In: Pitcher T.J., Hart P.J.B., Pauly D. (Eds.), Reinventing fisheries management, Kluwer Academic Publishers, Fish Fish. Ser. 23, 3-17.
Caddy J.F., Csirke J., Garcia S.M., Grainger R.J.R., 1998, How pervasive is "Fishing down marine food webs?" Science 282, 1383.
Caddy, J.F., Garibaldi, L., 2000, Apparent changes in the trophic composition of world marine harvests: the perspective from the FAO catch database. Ocean Coast. Manage. 43, 615-655. CrossRef
Cousins, S.H., 1991, Species diversity measurement: choosing the right index. Trends Ecol. Evol. 6, 190-192. CrossRef
Daget J., 1979, Les modèles mathématiques en écologie. Masson, Paris.
Deegan L.A., Finn J.T., Ayvazian S.G., Ryder-Kieer C.A., Buonaccorsi J., 1997, Development and validation of an Estuarine Biotic Integrity Index. Estuaries 20, 601–617.
Faure V., 2000, Dynamiques spatiale et temporelle des populations de poulpe (Octopus vulgaris) en Afrique de l'Ouest: influence des fluctuations environnementales et des relations interspécifiques. Thèse Université de Montpellier II, France.
Froese R., Pauly D., 2002, Fish-Base, concepts, design and data sources. International Center for Living Aquatic Resources Management (ICLARM), Manila, Philippines.
Garcia S.M., Newton C., 1997, Current situation, trends and prospects in catch fisheries. In: Pikitch E.K., Huppert D.D., Sissenwine M.P. (Eds.), Global trends in fisheries management. Amer. Fish. Soc. Symp. 20, Bethesda, MD, pp. 3-27.
Gislason, H., Sinclair, M., Sainsbury, K., O'Boyle, R., 2000, Symposium overview: incorporating ecosystem objectives within fisheries management. ICES J. Mar. Sci. 57, 468-475. CrossRef
Gulland J.A., Garcia S., 1984, Observed patterns in multispecies fisheries. In: May R.M. (Ed.), Exploitation of marine communities, Springer-Verlag, Berlin, pp. 155-190.
Hall S.J., 1999, The effects of fishing on marine ecosystems and communities. Blackwell Science, Great Britain.
Harrison T.D., Cooper J.A.G., Ramm A.E.L., 2000, State of South African estuaries: geomorphology, ichthyofauna, water quality and aesthetics. Department of Environmental Affairs and Tourism, State of the Environment Series Report No. 2.
Hurlbert, S.H., 1971, The nonconcept of species diversity: a critique and alternative parameters. Ecology 52, 577-586. CrossRef
ICES/SCOR symposium, 2000, Ecosystem effects of fishing. ICES J. Mar. Sci. 57, 465-791. CrossRef
Jennings, S., Kaiser, M.J., 1998, The effects of fishing on marine ecosystems. Adv. Mar. Biol. 34, 201-351. CrossRef
Laë R., 1997a. Estimation des rendements de pêche des lacs africains au moyen de modèles empiriques. Aquat. Living Resour. 10, 83-92.
Laë R., 1997b. Does overfishing lead to a decrease in catches and yields? An example of two West African coastal lagoons. Fish. Manag. Ecol. 3, 101-116.
Laë R., Bousquet F., 1996, PECHART: Logiciel de saisie et de traitement des enquêtes de pêche artisanale. LOGORSTOM, 70 p.
Laë, R., Lek, S., Moreau, J., 1999, Predicting fish yield of African lakes using neural network. Ecol. Model. 120, 325-335. CrossRef
Laë R., Weigel J.Y., 1995a, Diagnostic halieutique et propositions d'aménagement : l'exemple de la retenue de Sélengué (Mali). FAO-PAMOS, 73 p.
Laë R., Weigel J.Y., 1995b, La retenue de Manantali au Mali. Diagnostic halieutique et propositions d'aménagement. FAO-PAMOS, 65 p.
Lauzanne L., 1983, Trophic relationships of fishes in lake Chad. In: Carmouze J.P., Durand J.R., Levëque C., (Eds.), Lake Chad ecology and productivity of a shallow tropical ecosystem. The Hague, W. Junk, Monographiae Biologicae, 53, pp. 489-518.
Levêque, C., 1995, Role and consequences of fish diversity in the functioning of African freshwater ecosystems: a review. Aquat. Living Resour. 8, 59-78. CrossRef
Murawski, S.A., Lange, A.M., Idoine, J.S., 1991, An analysis of technical interactions among Gulf of Maine mixed-species fisheries. ICES Mar. Sci. Symp. 193, 237-252.
Nelson K., Soule M., 1987, Genetical conservation of exploited fishes. In: Ryman N., Utter F. (Eds.), Population genetics and fisheries management. Washington, Washington Sea Grant.
Oberdorff, T., Hughes, R.M., 1992, Modification of an index of biotic integrity based on fish assemblages to characterize rivers of the Seine Basin, France. Hydrobiologia 228, 117–130. CrossRef
Paller, M., Reichert, M., Dean, J.M., 1996, Use of the fish communities to assess environment impacts in South Carolina coastal plain streams. T. Am. Fish. Soc. 125, 633-644. 2.3.CO;2>CrossRef
Paugy D., Levêque C., 1999, Régimes alimentaires et réseaux trophiques. In: Levêque C., Paugy D. (Eds.), Les poissons des eaux continentales africaines, Diversité, Ecologie, Utilisation par l'homme. Éditions de l'IRD, Paris, pp. 167-190.
Pauly, D., Christensen, V., Daldgaard, J., Froese, R. Torres, F Jr., 1998, Fishing down marine food webs. Science 279, 860-863. CrossRef
Post, D.M., Pace, M.L., Hairston, N.G.L., 2000, Ecosystem size determines food-chain length in lakes. Nature 405, 1047-1049. CrossRef
Rapport, D.J., Regier, H.A., Hutchinson, T.C., 1985, Ecosystem behaviour under stress. Am. Nat. 125, 617-640. CrossRef
Regier, H.A., Loftus, K.H., 1972, Effects of fisheries exploitation on Salmonid communities in oligotrophic lakes. J. Fish. Res. Bd. Canada 30, 1992-1999. CrossRef
Rochet, M.J., 2000, May life history traits be used as indices of population viability? J. Sea Res. 44, 145-157. CrossRef
Rochet, M.J., Trenkel, V.M., 2003, Which community indicators can measure the impact of fishing? A review and proposals. Can. J. Fish. Aquat. Sci. 60, 86-99. CrossRef
Simpson A.C., 1982, A review of the database on tropical multispecies stocks in the southeast Asian region. In: Pauly D., Murphy G.L. (Eds.), Theory and Management of Tropical Fisheries. ICLARM/CSIRO, Cronulla, Australia, pp. 5-32.
Soto-Galera, E., Diaz-Pardo, E., Lopez-lopez, E., Lyons, J., 1998, Fish as indicators of environmental quality in the Rio Lerma Basin, Mexoci. Aquat. Ecosyst. health manage 3, 267-276.
Trenkel, V.M., Rochet, M.J., 2003, Performance of indicators derived from abundance estimates for detecting the impact of fishing on a fish community. Can. J. Fish. Aquat. Sci. 60, 67-85. CrossRef
Washington, H.G., 1984, Diversity, biotic and similarity indices. A review with special relevance to aquatic ecosystems. Water Res. 18, 653-694.
Whitfield, A.K., 1996, Fishes and the environmental status of South African estuaries. Fish. manage Ecol. 3, 45-57. CrossRef
Whitfield A.K., Elliott M., 2002, Fishes as indicators of environmental and ecological changes within estuaries: a review of progress and some suggestions for the future. J. Fish. Biol. 61 (Suppl. A), 229-250.