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Feeding ecology of conger eels (Conger conger) in north-east Atlantic waters

  • José C. Xavier (a1) (a2), Yves Cherel (a2), Carlos A. Assis (a3), João Sendão (a1) and Teresa C. Borges (a1)...

Abstract

In order to understand how marine ecosystems function, it is essential to study the trophic interactions among the community members, particularly from poorly known regions. In this study, the feeding ecology and diet of conger eels, Conger conger, an abundant fish species with commercial interest, was examined in the north-east Atlantic, off Algarve (southern Portugal) between May 2005 and August 2006. The diet was characterized by species composition, size and mass of prey. Conger eels are opportunistic feeders, cannibalistic, feeding on benthopelagic/pelagic prey (67% by mass and 71% by number) but also benthic prey (32% by mass and 29% by number). Fish (67.8±4.7% in mass) are the main prey of conger eels, followed by cephalopods (16.5±3.8%) and crustaceans (15.6±3.7%). The most numerous (identifiable) fish consumed were Capros aper, occurring in 90% of the stomach samples that contained food and representing 1.4% in mass, and Scomber japonicus, the most important fish in mass (21.1%), which occurred in 4.2% of the stomach samples that contained food. The present study shows that octopodids can play a more important role in the diet of conger eels than previously thought. Of the species preyed upon by conger eels, six species (21% of the total prey taxa) are caught commercially (Trachurus trachurus, Scomber japonicus, Micromesistius poutassou, Helicolenus dactylopterus and Conger conger) by local fisheries. As discards by local trawl and longline fisheries do not correspond with the diet of C. conger, it is likely that most prey of C. conger in rocky areas were caught actively in that study region.

Copyright

Corresponding author

Correspondence should be addressed to: J.C. Xavier, Institute of Marine Research, University of Coimbra, 3004-517 Coimbra, Portugal email: JCCX@cantab.net

References

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Assis, C.A. (2000) Estudo Morfológico dos Otólitos Sagitta, Asteriscus e Lapillus de Teleósteos (Actinopterygii, Teleostei) de Portugal Continental. Sua Aplicação em Estudos de Filogenia, Sistemática e Ecologia. PhD thesis. Universidade de Lisboa, Lisboa, Portugal.
Assis, C.A. (2004) Guia para a Identificação de Algumas Famílias de Peixes Ósseos de Portugal Continental, Através da Morfologia dos seus Otólitos Sagitta. Câmara Municipal de Cascais, Cascais, 190 pp.
Barreiros, J.P., Morato, T., Santos, R.S. and Borba, A.E. (2003) Inter-annual changes in the diet of the almaco jack, Seriola Rivoliana (Perciformes: Carangidae) from the Azores. Cybium 27, 3740.
Bauchot, M.L. and Saldanha, L. (1986) Congridae. In Whitehead, P.J.P., Bauchot, M.-L., Hureau, J.-C., Nielsen, J. and Tortonese, E. (eds) Fishes of the North-Eastern Atlantic and the Mediterranean. Paris: UNESCO, pp. 567574.
Borges, T.C., Erzini, K., Bentes, L., Costa, M.E., Gonçalves, J.M.S., Lino, P.G., Pais, C. and Ribeiro, J. (2001) By-catch and discarding practices in five Algarve (southern Portugal) métiers. Journal of Applied Ichthyology 17, 101114.
Cabral, H.N. and Murta, A.G. (2002) The diet of blue whiting, hake, horse mackerel and mackerel off Portugal. Journal of Applied Ichthyology 18, 1423.
Campana, S.E. (2004) Photographic atlas of fish otoliths of the North-east Atlantic ocean. Ottawa, Ontario: NRC Research Press, 284 pp.
Castro, M., Araújo, A. and Monteiro, P. (2005) Fate of discards from deep water crustacean trawl fishery of the south coast of Portugal. New Zealand Journal of Marine and Freshwater Research 39, 437446.
Cau, A. and Manconi, P. (1984) Relationship of feeding, reproductive cycle and bathymetric distribution in Conger conger. Marine Biology 81, 147151.
Clarke, M.R. (1986) A handbook for the identification of cephalopod beaks. Oxford: Clarendon Press.
Clarke, M.R. (2006) Oceanic cephalopod distribution and species diversity in the eastern North Atlantic. Arquipélago. Life and Marine Sciences 23A, 2746.
Clarke, M.R., Clarke, D.C., Martins, H.R. and Silva, H.M. (1995) The diet of swordfish (Xiphias gladius) in Azorean waters. Arquipélago. Life and Marine Sciences 13, 5369.
Clarke, M.R., Clarke, D.C., Martins, H.R. and Silva, H.M. (1996) The diet of the blue shark (Prionace glauca L.) in Azorean waters. Arquipélago. Life and Marine Sciences 14, 4156.
Collette, B.B. and Nauen, C.E. (1983) FAO Species Catalogue. Vol. 2. Scombrids of the world. An annotated and illustrated catalogue of tunas, mackerels, bonitos and related species known to date. FAO Fisheries Synopsis 125(122), 137 pp.
Cortés, E. (1999) Standardized diet composition and trophic levels of sharks. ICES Journal of Marine Science 56, 707717.
Falciai, L. and Minervini, R. (1995) Guia de los crustaceos decapodes de Europa. Ediciones Omega, S.A. Plaró, 26-08006 Barcelona.
Granadeiro, J.P., Monteiro, L.R. and Furness, R.W. (1998) Diet and feeding ecology of Calonectris diomedea in the Azores, north-east Atlantic. Marine Ecology Progress Series 166, 267276.
Härkönen, T. (1986) Guide to the otoliths of the bony fishes of the Northeast Atlantic. Denmark: Danbiu ApS, 256 pp.
Hecht, T. (1987) A guide to the otoliths of Southern Ocean fishes. South African Journal of Antarctic Research 17, 287.
Lopes, M., Murta, A.G. and Cabral, H.N. (2006) The ecological significance of the zooplanktivores, snipefish Macroramphosus spp. and boarfish Capros aper, in the food web of the south-east North Atlantic. Journal of Fish Biology 69, 363378.
Lu, C.C. and Ickeringill, R. (2002) Cephalopod beak identification and biomass estimation techniques: tools for dietary studies of southern Australian finfishes. Museum Victoria Science Reports 6, 165.
Machado, P.B., Gordo, L.S. and Figueiredo, I. (2004) Skate and ray species composition in mainland Portugal from the commercial landings. Aquatic Living Resources 17, 231234.
Monteiro, P., Araujo, A., Erzini, K. and Castro, M. (2001) Discards of the Algarve (southern Portugal) crustacean trawl fishery. Hydrobiologia 449, 267277.
Morato, T., Sola, E., Gros, M.P. and Menezes, G. (1999) Diets of forkbeard (Phycis phycis) and conger eel (Conger conger) off the Azores during spring of 1996 and 1997. Arquipélago. Life and Marine Sciences 17A, 5164.
Morato, T., Solá, E., Grós, M.P. and Menezes, G. (2003) Diets of thornback ray (Raja clavata) and tope shark (Galeorhinus galeus) in the bottom longline fishery of the Azores, northeastern Atlantic. Fishery Bulletin 101, 590602.
Moreira, F. (1990) Food of swordfish, Xiphias gladius (Linnaeus, 1758), off the Portuguese coast. Journal of Fish Biology 36, 623624.
Mytilineou, C., Politou, C.-Y., Papaconstantinou, C., Kavadas, S., D'Onghia, G. and Sion, L. (2005) Deep-water fish fauna in the Eastern Ionian Sea. Belgium Journal of Zoology 135, 229233.
Neiva, J., Coelho, R. and Erzini, K. (2006) Feeding habits of velvet belly lanternshark Etmopterus spinax (Chondrichthyes: Etmopteridae) off the Algarve, southern Portugal. Journal of the Marine Biological Association of the United Kingdom 86, 17.
Okach, J.I.O. and Dadzie, S. (1988) The food, feeding habits and distribution of the siluroid catfish, Bagrus docmac (Forsskål) in Kenya waters of Lake Victoria. Journal of Fish Biology 32, 8594.
O'sullivan, S., Moriarty, C. and Davenport, J. (2004) Analysis of the stomach contents of the European conger eel Conger conger in Irish waters. Journal of the Marine Biological Association of the United Kingdom 84, 823826.
Pauly, D., Alder, J., Bennett, E., Christensen, V., Tyedmers, P. and Watson, R. (2003) The future for fisheries. Science 302, 13591361.
Pauly, D. and Christensen, V. (1995) Primary production required to sustain global fisheries. Nature 374, 255257.
Pauly, D., Christensen, V., Dalsgaard, J., Froese, R. and Torres, F. Jr (1998) Fishing down marine food webs. Science 279, 860863.
Pauly, D., Christensen, V., Guénette, S., Pitcher, T.J., Sumaila, U.R., Walters, C.J., Watson, R. and Zeller, D. (2002) Towards sustainability in world fisheries. Nature 418, 689695.
Santos, J. and Borges, T.C. (2001) Trophic relationships in deep-water fish communities off Algarve, Portugal. Fisheries Research 51, 337341.
Shannon, C. and Weaver, W. (1949) The mathematical theory of communication. Urbana: University of Illinois Press.
Silva, A. (1999a) Feeding habits of John Dory, Zeus faber, off the Portuguese continental coast. Journal of the Marine Biological Association of the United Kingdom 79, 333340.
Silva, M.A. (1999b) Diet of common dolphins, Delphinus delphis, off the Portuguese continental coast. Journal of the Marine Biological Association of the United Kingdom 79, 531540.
Smale, M.J., Watson, G. and Hecht, T. (1995) Otolith atlas of Southern African marine fishes. Ichthyological Monographs of the JLB Smith Institute of Ichthyology, Grahamstown, South Africa.
Tregenza, N.J.C., Berrow, S.D., Hammond, P.S. and Leaper, R. (1997) Harbour porpoise (Phocoena phocoena L.) by-catch in set gillnets in the Celtic Sea. ICES Journal of Marine Science 54, 896904.
Whitehead, P.J.P., Bauchot, M.-L., Hureau, J.-C., Nielsen, J. and Tortonese, E. (1986) Fishes of the North-eastern Atlantic and the Mediterranean. Vols. I–III, Paris: UNESCO, 1473 pp.
Xavier, J.C., Croxall, J.P. and Reid, K. (2003) Inter-annual variation in the diet of two albatross species breeding at South Georgia: implications for breeding performance. Ibis 145, 593610.
Xavier, J.C., Rodhouse, P.G., Purves, M.G., Daw, T.M., Arata, J. and Pilling, G.M. (2002) Distribution of cephalopods recorded in the diet of Patagonian toothfish (Dissostichus eleginoides) around South Georgia. Polar Biology 25, 323330.
Zariquiey-Alvarez, R. (1968) Crustaceos decapodes ibericos. Investigacion Pesquera, Barcelona.

Keywords

Feeding ecology of conger eels (Conger conger) in north-east Atlantic waters

  • José C. Xavier (a1) (a2), Yves Cherel (a2), Carlos A. Assis (a3), João Sendão (a1) and Teresa C. Borges (a1)...

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