Life History of the Hawaiian Fish Kuhlia sandvicensis as Inferred from Daily Growth Rings of Otoliths

Abstract

Kuhlia sandvicensis, the aholehole, is a native Hawaiian fish found in both marine and freshwater habitats. In the lower reaches of streams, they are predators on stream fishes, invertebrates, and insects. Aholehole are an important food fish in the Hawaiian Islands and were often used by ancient Hawaiians in traditional ceremonies. Although aholehole are an important part of stream ecosystems and Hawaiian culture, little is known about their life history, specifically, whether a freshwater phase is obligatory. In this study, light microscopy and electron microprobe techniques were used to analyze otolith daily increments. The analysis estimated age of juveniles and provided information regarding salinity of a fish's habitat at specific points in its life. Sr/Ca profiles from otoliths of juvenile and adult fish from fresh and salt water indicated that this species' use of stream habitats is facultative. Unlike Hawaiian freshwater gobies and at least one other member of the Kuhliidae from the Western Pacific, there is no physiological requirement of fresh water at a specific point in the life cycle of K. sandvicensis. Future research will provide a greater understanding as to the importance of streams as nursery habitats for this species. The research is expected to bolster the argument for maintaining the stream-ocean corridor for access by amphidromous gobies and perhaps also for the aholehole.