Hostname: page-component-586b7cd67f-g8jcs Total loading time: 0 Render date: 2024-11-28T06:16:03.709Z Has data issue: false hasContentIssue false
  • English
  • Français

How do seaweed farms influence local fishery catches in a seagrass-dominated setting in Chwaka Bay, Zanzibar?

Published online by Cambridge University Press:  22 June 2006

Johan S. Eklöf ,
Maricela de la Torre-Castro ,
Camilla Nilsson  and
Patrik Rönnbäck
Johan S. Eklöf
Affiliation:
Department of Systems Ecology, Stockholm University, S-106 91 Stockholm, Sweden
Maricela de la Torre-Castro
Affiliation:
Department of Systems Ecology, Stockholm University, S-106 91 Stockholm, Sweden
Camilla Nilsson
Affiliation:
Department of Systems Ecology, Stockholm University, S-106 91 Stockholm, Sweden
Patrik Rönnbäck
Affiliation:
Department of Systems Ecology, Stockholm University, S-106 91 Stockholm, Sweden
Get access

Abstract

Seaweed farming is often depicted as a sustainable form of aquaculture, contributing to poverty reduction and financial revenues in producer countries. However, farms may negatively affect seagrasses and associated organisms (e.g. invertebrate macrofauna) with possible effects on the flow of ecosystem goods and services to coastal societies. The present study investigates the influence of a seaweed farm, and the farmed seaweed Eucheuma denticulatum in particular, on fishery catches using a traditional fishing method (“madema” basket traps) in Chwaka bay (Zanzibar, Tanzania). The results suggest that a seaweed farm, compared to a seagrass bed, had no influence on catch per unit effort (no. of individuals per catch, or catch weight) or no. of species per catch, but significantly affected catch composition (i.e. how much that was caught of which species). The two species contributing most to differences between the sites were two economically important species; the herbivorous seagrass rabbit fish Siganus sutor, which was more common in the seaweed site and is known to graze on the farmed algae; and the benthic invertebrate feeder chloral wrasse Cheilinus chlorourus, more common in the seagrass site. Compared to vegetation-free bottoms, however, the catches were 3−7 times higher, and consisted of a different set of species (ANOSIM global R > 0.4). As traps placed close to the seaweeds fished three times more fish than traps placed on sand patches within the seaweed farm, the overall pattern is attributed to the presence of submerged vegetation, whether seagrass or seaweed, probably as shelter and/or food for fish. However, qualitative differences in terms of spatial and temporal dynamics between seagrass beds with and without seaweed farms, in combination with other factors such as institutional arrangements, indicate that seaweed farms cannot substitute seagrass beds as fishing grounds.

Keywords

Artisanal fisheriesFish trap catchesSeaweed farmingAquacultureRhodophytaMeadowsSeagrass lossIndian Ocean
Type
Research Article
Information
Aquatic Living Resources , Volume 19 , Issue 2 , April 2006 , pp. 137 - 147
Copyright
© EDP Sciences, IFREMER, IRD, 2006

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, A.J., Locascio, J.V., Robbins, B.D., 2004, Microhabitat use by post-settlement stage estuarine fish: evidence from relative abundance and predation among habitats. J. Exp. Mar. Biol. Ecol. 299, 17-33. CrossRef
Arrivillaga, A., Balz, D.M., 1999, Comparison of fishes and macroinvertebrates on seagrass and bare-sand sites on Guatemala's Atlantic coast. Bull. Mar. Sci. 65, 301-319.
Ask E. I., Batibasaga A., Zertuche-Gonzalés J.A., de San, M., 2001, Three decades of Kappaphycus alvarezii (Rhodophyta) introduction to non-endemic locations. In: Chapman A.R.O., Anderson R.J., Vreeland V.J., Davison I.R (Eds.). 17th International Seaweed Symposium, Cape Town, Oxford University Press, pp. 49-57.
Bergman, K.C., Svensson, S., Ohman, M.C., 2001, Influence of algal farming on fish assemblages. Mar. Pollut. Bull. 42, 1379-1389. CrossRef
Bianchi G., 1985, FAO Species Identification Sheets for Fishery Purposes. Field guide to commercial marine and brackish water species of Tanzania. Rome, FAO.
Bryceson, I., 2002, Coastal Aquaculture developments in Tanzania: Sustainable and non-sustainable experiences. W. Ind. Ocean J. Mar. Sci. 1, 1-10.
Burgess W.E., Axelrod, H.R., Hunziker III R.E., 2000, Dr. Burgess's atlas of marine aquarium fishes. Third edition. Neptune City, T.F.H. Publications.
Cederlof, U., Rydberg, L., Mgendi, M., Mwaipopo, O., 1995, Tidal exchange in a warm tropical lagoon: Chwaka Bay, Zanzibar. Ambio 24, 458-464.
Clarke K.R., 1988, Detecting change in benthic community structure. In: Proceedings of the XIVth International Biometric Conference, Namur: Invited Papers, Gemblous, Société Adophe Quélét.
Clarke, K.R., 1993, Non-parametric multivariate analyses of changes in community structure. Aust. J. Ecol. 18, 117-143. CrossRef
Clarke, K.R., Ainsworth, M., 1993, A method of linking multivariate community structure to environmental variables, Mar. Ecol. Prog. Ser. 92, 205-219. CrossRef
de la Torre-Castro, M., Ronnback, P., 2004, Links between humans and seagrasses- an example from tropical East Africa. Ocean Coast. Manage. 47, 361-387. CrossRef
Eklöf, J.S., de la Torre Castro, M., Adelsköld, L., Jiddawi, N.S., Kautsky, N., 2005, Differences in macrofaunal and seagrass assemblages in seagrass beds with and without seaweed farms. Estuar. Coast. Shelf Sci. 63, 385-396. CrossRef
Eklöf J.S., Henriksson R., Kautsky N., in press, Effects of tropical open-water seaweed farming on seagrass ecosystem structure and function. Mar. Ecol. Prog. Ser.
Ferrell, D.J., Bell, J.D., 1991, Differences among assemblages of fish associated with Zostera capricorni and bare sand over a large spatial scale. Mar. Ecol. Prog. Ser. 72, 15-24. CrossRef
Froese R., Pauly. D. (Eds.), 2005, FishBase. World Wide Web electronic publication. http://www.fishbase.org (Oct. 2005).
Gell F., 1999, Fish and fisheries in the seagrass beds of Quirimba archipelago, northern Mozambique. Ph.D. Thesis, University of York.
Gell, F.R., Whittington, M.W., 2002, Diversity of fishes in seagrass beds in the Quirimba archipelago, northern Mozambique. Mar. Freshw. Res. 53, 115-121. CrossRef
Gillianders B.W., 2006, Seagrasses, fish and fisheries. In: Larkum A.W.D, Orth R.J., Duarte C.M. (Eds.). Seagrasses: Biology, Ecology and Conservation, Netherlands, Springer, 503-536.
Gullström, M., de la Torre Castro, M., Bandeira, S.O., Björk, M., Dahlberg, M., Kautsky, N., Ronnback, P., Ohman, M.C., 2002, Seagrass ecosystems in the Western Indian Ocean. Ambio 31, 588-596. CrossRef
Gullström M., Lundén B., Bodin M., Kangwe J., Öhman M.C., Mtolera M.S.P., Björk M., 2006. Assessment of changes in the seagrass-dominated submerged vegetation of tropical Chwaka Bay (Zanzibar) using satellite remote sensing. Estuar. Coast. Shelf Sci. 67, 399-408.
Holm, S., 1979, A simple sequentially rejective multiple test procedure. Scand. J. Stat. 6, 65-70.
Jackson, E.L., Rowden, A.A., Attrill, M.J., Bossey, S.J., Jones, M.B., 2001, The importance of seagrass beds as a habitat for fishery species. Ocean. Mar. Biol. 39, 269-303.
Jenkins, G.P., Wheatley, M.J., 1998, The influence of habitat structure on near shore fish assemblages in southern Australian embayment: Comparison of shallow seagrass, reef-algal and unvegetated sand habitats, with emphasis on their importance to recruitment. J. Exp. Mar. Biol. Ecol. 221, 147-172. CrossRef
Jiddawi, N.S., Ohman, M.C., 2002, Marine fisheries in Tanzania. Ambio 31, 518-527. CrossRef
Kangwe J. 2006, Calcareous algae of a tropical lagoon. Primary productivity, calcification and carbonate production. Ph.D. Thesis, Stockholm University.
Kaunda-Arara, B., Rose, G.A., 2004, Effects of marine reef national parks on fishery CPUE in coastal Kenya. Biol. Cons. 118, 1-13. CrossRef
Lieske E., Myers R., 2001, Coral Reef Fishes. Indo-Pacific and Caribbean. London, HarperCollins.
McClanahan, T.R., Kaunda-Arara, B., 1996, Fishery recovery in a coral-reef marine park and its effect on the adjacent fishery. Cons. Biol. 10, 1187-1199. CrossRef
McClanahan, T.R., Mangi, S., 2000, Spillover of exploitable fishes from a marine park and its effect on the adjacent fishery. Ecol. Appl. 10, 1792-1805. CrossRef
McClanahan, T.R., Mangi, S.C., 2004, Gear-based management of a tropical artisanal fishery based on species selectivity and capture size. Fish. Manage. Ecol. 11, 51-60. CrossRef
Mtolera M.S.P., Ngoile A.K., Semesi A.K., 1992, Ecological considerations in sustainable Eucheuma farming in Tanzania. In: Proc. 1st international workshop on sustainable seaweed resources development in sub-Saharan Africa. 22-29 March 1992. Windhoek, University of Namibia, Namibia, pp. 257-263.
Muzuka A.N.N., Kangwe J.W., Nyandwi N., Wannas K.O., Mtolera M.S.P., Bjork M., 2001, Preliminary results on the sediment sources, grain size distribution and percentage cover of sandproducing Halimeda species and associated flora in Chwaka Bay. In: Richmond MD, Francis J. (Eds.), Marine science development in Tanzania and Eastern Africa. Proc. 20th ann. conference on advances in marine science in Tanzania. Zanzibar, IMS/WIOMSA, pp. 51-60.
Nagelkerken, I., van der Velde, G., 2004, A comparison of fish communities of subtidal seagrass beds and sandy seabeds in 13 marine embayments of a Caribbean island, based on species, families, size distribution and functional groups. J. Sea Res. 52, 127-147. CrossRef
Neish I.C., 2003, The ABC of Eucheuma Seaplant Production. http://www.surialink.com/get/ (Oct. 2005).
Nilsson C., 2005, Comparison of catches and income for dema trap fishery in seagrass beds and seaweed farms – based on the local fishing techniques of dema fishermen. M.Sc. Thesis. Department of Systems ecology, Stockholm University.
Pollard, D.A., 1984, A review of ecological studies on seagrass-fish communities, with special reference to Australia. Aquat. Bot. 18, 3-42. CrossRef
Petterson-Lofquist, P., 1995, The development of open-water algae farming in Zanzibar: reflections on the socioeconomic impact. Ambio 24, 487-491.
Russell, D.J., 1983, Ecology of the imported red seaweed Eucheuma striatum Schmitz on Coconut Island, Oahu, Hawaii. Pacific Sci. 37, 87-107.
Ronnback, P., Bryceson, I., Kautsky, N., 2002, Coastal aquaculture development in Eastern Africa and the Western Indian Ocean: prospects and problems for food security and local economies. Ambio 31, 537-542. CrossRef
Semesi S., 2002, Ecological and socio-economic impacts from Eucheuma seaweeds in Zanzibar, Tanzania. M.Sc. Thesis, Noragric, Agricultural university of Norway.
Short F.T., Coles R.G., 2001, Global seagrass research methods. Amsterdam, Elsevier.
Smith M.M., Heemstra P.C., 2003, Smith's Sea Fishes. Cape Town, Struik Publishers.
Sogard, S.M., 1992, Variability in growth-rates of juvenile fishes in different estuarine habitats. Mar. Ecol. Prog. Ser. 85, 35-53. CrossRef
Stimson, J., Larned, S.T., Conklin, E., 2001, Effects of herbivory, nutrient levels, and introduced algae on the distribution and abundance of the invasive macroalga Dictyosphaeria cavernosa in Kaneohe Bay, Hawaii. Coral Reefs 19, 343-357. CrossRef
Warwick, R.M., Clarke, K.R., Suharsono, 1990, A statistical analysis of coral community responses to the 1982-1983 El Nino in the Thousand Island. Coral Reefs 8, 171-179. CrossRef
Wheeler A., 1980, Fish-algal relations in temperate waters. In: Price J.H., Irvine D.E.G., Farnham W.F. (Eds.). The shore environment: Vol. 2: Ecosystems. London, Academic Press, pp. 677-698.
Zemke-White W.L., 2003, Assessment of the current knowledge on the environmental impacts of seaweed farming in the tropics. In: Proc. Asia-Pacific Conference on Marine Science and Technology, 12-16 May 2002, Kuala Lumpor, Malaysia.