Self-recruitment in a coral reef fish population

The question of how far the larvae of marine organisms disperse is fundamen tal to an understanding of their population dynamics(1-3), the management o f exploited species(4,5) and the conservation of marine biodiversity(6,7), It is generally assumed that larvae disperse away from their natal populati on so that local populations operate as 'open' systems, driven by recruitme nt of larvae from other sub-populations(8). However, this assumption has ne ver been critically tested. Here we show for the first time that juveniles from a coral reef fish population can return to their natal reef. We marked otoliths (ear bones) of over 10 million developing embryos of the damselfi sh, Pomacentrus amboinensis, at Lizard Island (Great Barrier Reef). Subsequ ently from an examination of 5,000 juveniles settling at the same location, we found 15 marked individuals. On the basis of an estimate of the proport ion of embryos marked (0.5-2%), as many as 15-60% of juveniles may be retur ning to their natal population (self-recruitment). We challenge the assumpt ion that long-distance dispersal is the norm for reef fish populations.