Identification of Nile tilapia (Oreochromis niloticus) and its hybrids in natural environments in Hawaii

Abstract

The history of tilapia in Hawaii began in the 1950s with the introduction of five species for recreational, research, and commercial purposes (Hida et al., 1962; Szyper et al., 2000). In 2000, the existing tilapia stocks were evaluated for their utility in establishing a tilapia producing industry (Szyper et al., 2000). The study showed that the stocks were inferior in terms of growth when compared to Nile tilapia (Oreochromis niloticus), a species that could not be imported for private and commercial use (Szyper et al., 2000). Supporters of the species' entry into Hawaii argued that it was already established in natural bodies of water, and its introduction would have little effect on the environment. Tilapia were collected from 10 sites throughout the state of Hawaii to determine if O. niloticus is indeed established in the wild. Total genomic DNA was extracted from fin clips. Potential species identification was based on the sequencing of the mitochondrial DNA control region (mtDNA CR). Unique sequences were compared with those published in GenBank. Nile tilapia was found on the island of Hawaii, and its potential hybrids were identified on the islands of Molokai, Maui, as well as Hawaii.