Growth, site fidelity, and grouper interactions of the Red Sea lionfish Pterois miles (Scorpaenidae) in its native habitat

The introduction of lionfish into the western Atlantic and Caribbean Sea is widely recognized as the most successful marine fish invasion documented to date. In an effort to improve our understanding of the life history characters that facilitated this unprecedented invasion, we performed a mark–release–recapture study with 36 tagged individuals to document life history characteristics of the Red Sea lionfish, Pterois miles, in its native habitat. Monthly growth rates of juveniles ranged from 4.0 to 10.8 mm month−1 independent of water temperature. Highest juvenile growth rates (> 9.0 mm month−1) occurred between May and August when water temperature increased from 22.5 to 28.0 °C, while growth rates dropped sharply between August and September when water temperature was consistently high. Adult lionfish had relatively constant growth rates of 4–6 mm month−1. Despite high site fidelity of some individuals, recapture success gradually declined from 83 to 3% during the 15-month study period. Thus, the consistent population density of 95 fish ha−1 likely reflected a well-balanced exchange of individuals with adjacent reef habitats. To identify biotic constraints that may limit native lionfish populations, interactions with seven potential predatory and/or competitive grouper species were also investigated. Significantly, fewer lionfish were encountered in micro-habitats, where the Red Sea groupers Aethaloperca rogaa and Cephalopholis miniata resided. In addition, the presence of large groupers (> 250 mm TL) was significantly correlated with reduced numbers of lionfish, while small groupers (≤ 250 mm TL) appeared to have no impact. Our field observations suggest that the biotic interactions (e.g., habitat competition, and depredation) between grouper species and lionfish may play a role in lionfish distribution. This study provides new insights into the growth and ecology of lionfish in their native habitats to help illuminate links to their documented success in the invaded range.