Eel community structure, fluvial recruitment of Anguilla marmorata and indication for a weak local production of spawners from rivers of Reunion and Mauritius islands
|Author(s)||Robinet Tony1, Feunteun Eric2, 6, Keith Philippe3, Marquet Gérard, Olivier Jean-Michel4, Reveillac Elodie2, Valade Pierre|
|Affiliation(s)||1 : Univ Tokyo, Ocean Res Inst, Behav & Ecol Grp, Nankano Ku, Tokyo 1648639, Japan.
2 : Univ La Rochelle, IFREMER, UMR6217, CNRS,CRELA, F-17000 La Rochelle, France.
3 : Museum Natl Hist Nat, F-75231 Paris, France.
4 : Univ Lyon 1, CNRS, UMR 5023, F-69622 Villeurbanne, France.
5 : Ctr Eaux Douces Sables, ARDA, F-97427 Etang Sale, Reunion.
|Source||Environmental Biology of Fishes (0378-1909) (Springer), 2007-02 , Vol. 78 , N. 2 , P. 93-105|
|WOS© Times Cited||21|
|Keyword(s)||Conservation, Reproductive turnover, Fluvial recruitment, Indian Ocean, Tropical eels|
|Abstract||Anguillid eels were sampled from permanent rivers in the Reunion and Mauritius islands, western Indian Ocean, with a standardized electrofishing method. A. marmorata was very dominant, corresponding to 91.7 and 90.7% of all the eels collected in Reunion and Mauritius, respectively. Three other species (A. mossambica, A. bicolor bicolor and A. nebulosa labiata) were also present in both islands. A. marmorata showed a strong altitudinal gradient of densities from the lower to upper zones, especially in the younger stages (TL < 250 mm), while A. mossambica was only found in the upper zones and A. bicolor bicolor occurred only in the lower zones (A. nebulosa labiata was rare). The eel species composition in freshwaters of both islands is very similar because these two adjoining islands are located in the same trail of drifting marine larvae. Mean estimated eel biomasses were noticeably low (11.1 and 22.2 kg h(-1) in Reunion and Mauritius islands, respectively), especially when compared to those of other tropical insular systems without any eel fishery (Comoros or Polynesia, more than 100 kg ha(-1)). Nevertheless, the fluvial recruitment of A. marmorata seemed to be regular during the surveyed period, staggering from October to April. The obvious lack of large eels in Mauritius but more significantly in Reunion suggests a high pressure from traditional fishery, and the local reproductive turnover is uncertain. Because sexual maturation seems to occur at a large body size for A. marmorata, as for temperate species, the Reunion and Mauritius rivers may only have a weak contribution to the regional production of spawners. However, the giant mottled eel population in the western Indian Ocean is believed to be panmictic at the regional scale, and may not rely exclusively on these islands' contribution. A comparison is made with those of freshwater systems in other tropical islands.|