Surviving under pressure and protection: a review of the biology, ecology and population status of the highly vulnerable grouper Epinephelus daemelii

Abstract

Epinephelus daemelii is a threatened serranid grouper species that is restricted to the south-western Pacific Ocean, ranging from eastern Australia to northern New Zealand and the Kermadec Islands. Declines in its abundance due to fishing pressure were reported as early as 1916. Aspects of this species’ biology and behaviour that make it vulnerable include its longevity, late age at maturity, protogynous hermaphroditism, territoriality and limited shallow reef habitat. Adults prefer complex habitat with caves and overhangs at depths of less than 50m, whereas juveniles live in rock pools, shallow intertidal reefs and estuaries. Epinephelus daemelii lives at least 65 years and reaches 170-cm total length. Individuals change sex from female to male at ~100–110cm and ~25 years. Absence of large (>100cm) fish across a large part of their range has implications for reproduction. Although nearly fully protected, incidental bycatch still occurs. A lack of long-term data hinders determination of population status, but abundance appears to be much lower than before, except in remote regions (Kermadec Islands, Elizabeth and Middleton reefs) with extensive no-fishing areas. Further prohibitions on fishing in key locations are likely to be important for the recovery and long-term survival of this species.