Self-recruitment in a coral reef fish population

The question of how far the larvae of marine organisms disperse is fundamental to an understanding of their population dynamics 1 , 2 , 3 , the management of exploited species 4 , 5 and the conservation of marine biodiversity 6 , 7 . It is generally assumed that larvae disperse away from their natal population so that local populations operate as ‘open’ systems, driven by recruitment of larvae from other sub-populations 8 . However, this assumption has never 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 damselfish, Pomacentrus amboinensis , at Lizard Island (Great Barrier Reef). Subsequently, 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 proportion of embryos marked (0.5–2%), as many as 15–60% of juveniles may be returning to their natal population (self-recruitment). We challenge the assumption that long-distance dispersal is the norm for reef fish populations.