Tropical eels Anguilla spp. recruiting to Réunion Island in the Indian Ocean: taxonomy, patterns of recruitment and early life histories

Abstract

Anguillid glass eels were sampled between October 2000 and October 2001 in an estu- arine goby-fry traditional fishery of Reunion Island (21° S, 56° E), Mascarene Islands, western Indian Ocean. Recruitment occurred from November to April. Among the 633 specimens collected, 4 species were identified by biometric measurements coupled with number of vertebrae (61.9% of the speci- mens were Anguilla marmorata, 19.4% A. bicolor bicolor, 18.3% A. mossambica and 0.3% A. nebu- losa labiata). A. mossambica had the shortest total length at recruitment (51.2 ± 2.7 mm), compared to A. marmorata (53.3 ± 2.5 mm) and A. bicolor bicolor (54.0 ± 2.1 mm). Most juvenile pigmentation corresponded to the glass eel stage (VA to VB). We extracted 34 otoliths and visualized their microstructure by SEM. The short-finned A. bicolor bicolor had the shortest leptocephalus stage (46.2 ± 5.8 d) and age at recruitment (79.8 ± 7.7 d). The long-finned glass eels had the same age at recruitment (120.2 ± 24.7 and 123.6 ± 17 d for A. marmorata and A. mossambica respectively) and the same leptocephalus stage duration (96.9 ± 26.4 and 102.1 ± 17.2 d for A. marmorata and A. mossam- bica respectively). Otolith readings and sampling dates showed that A. mossambica hatched about 2 mo earlier than A. marmorata. Their identical early life histories should imply adjoining spawning grounds, whereas A. bicolor bicolor must spawn in a distinctive location. Hypotheses for spawning area locations are discussed as a function of the region's oceanic circulation.