Individually-unique Spot Patterns of Young of the Year Giant Sea Bass, Stereolepis gigas in Captive-raised Fish

Abstract

Young of the year giant sea bass spend the first several months after planktonic settlement within recreational dive limits, where they are available for underwater study. After planktonic settlement, young of the year giant sea bass enter color phases where a pattern of black spots unique to individual fish appears distinct against a lighter background. To determine whether or not underwater photos of spot patterns might be used to identify and track individuals, several early-stage giant sea bass were captured and raised at public aquaria. Both sides of each fish were planned to be photographed monthly for a year from the capture date. The black spots of young of the year giant sea bass are so few and so distinct that computer programs developed to discern individuals of species with complicated spot patterns are not necessary for re-identification of individuals. Each of three fish that survived twelve months in captivity could be individually identified by eye using photographs of their spot patterns for a year after collection. Two other fish that expired after several months could also be individually distinguished through photographs. This information opens the door to underwater field studies using photography as a passive mark and recapture method for studying young of the year giant sea bass along soft-bottomed nursery beaches where they can be found for the first several months after settlement.