A probable spawning aggregation of the leather bass Dermatolepis dermatolepis (Boulenger) in the Revillagigedo Archipelago, México

The leather bass Dermatolepis dermatolepis (Boulenger, 1895) is a poorly known grouper living on coral and rocky reefs in the eastern Pacific Ocean. One of only three species in the genus Dermatolepis (family Serranidae, subfamily Epinephelinae), the leather bass distribution ranges from southern California to Ecuador, including the Gulf of California, the Galapagos Islands and other offshore islands (Heemstra & Randall, 1993) such as the Revillagigedo Archipelago. Juveniles settle among the spines of the long-spined sea urchin Diadema mexicana. Adults are predominantly solitary, although they frequently occur in association with schools of herbivores that facilitate leather bass predation on benthic fishes and crustaceans (Montgomery, 1975). Of the 122 reef fish species in Revillagigedo recorded on scuba dives in February 2006, the leather bass was the only large grouper (c. 1 m total length, LT) and one of the main reef predators. The Revillagigedo Archipelago lies c. 650 km south-west of Baja California and includes four volcanic islands: Socorro, San Benedicto, Roca Partida and Clarion (Fig. 1). The islands are separated from one another by as little as 53 km