Pelagic larval duration of two diadromous species of Kuhliidae (Teleostei: Percoidei) from Indo-Pacific insular systems

Diadromous fish species in the family Kuhliidae are able to colonise freshwater systems in Indo-Pacific islands, but their life cycle and the mechanisms involved in the colonisation of such ecosystems are poorly documented. After validating the daily rate of increment deposition in otoliths of Kuhlia rupestris, we estimated the pelagic larval duration (PLD) of K. rupestris, widely distributed in the Indo-Pacific area, and K. sauvagii, endemic to the Indian Ocean. Median PLD of K. rupestris was significantly longer than that of K. sauvagii (40.6 +/- 6.9 and 32.3 +/- 3.4 days (+/- s.d.), respectively), implying that the PLD is probably one factor controlling the extent of distribution range in Kuhlia. Within K. rupestris, individuals from New Caledonia had longer PLDs than those from Reunion Island (44.3 +/- 6.7 and 37.3 +/- 4.7 days (+/-s.d.) respectively). Further research on larval migration is needed to determine whether this was due to different environmental conditions or is population-specific. Interestingly, the PLD of these Kuhlia species is shorter than the PLD of other tropical diadromous fishes. These results improve our understanding of the dispersal strategies of freshwater fauna, to colonise and persist in tropical islands.