Georgia Journal of Science

Article Title



The introduction of invasive species can threaten the natural biodiversity of ecosystems and potentially lead to environmental as well as economic damages. Many successful invasive species possess several of characteristics (e.g., rapid growth, high reproduction rates, tolerance of varying conditions, and phenotypic plasticity) that allow them to infiltrate ecosystems--disrupting important ecological processes and threatening native species. On the other hand, these same traits make them ideal candidates for certain industries such as aquaculture. Within the aquaculture industry, tilapia are the third most popular farmed fish globally and are a vital part of many economies. For example, in Hawaii, tilapia were first introduced in the 1950s and have been successfully farmed there ever since. Unfortunately, a few tilapia species have since escaped from aquaculture facilities and invaded freshwater systems, negatively impacting native Hawaiian biota and leading to the formation of hybrid species. In response, stringent regulations on tilapia importation were put in place but have recently been lifted. To monitor possible effects of lifting these restrictions, it is imperative to establish baseline genetic data on the tilapia species present in Hawaii’s freshwater streams. Such data has the potential to aid in the development of reliable conservation and resource management strategies for native biota and established tilapia populations throughout Hawaii. Given this, the objective of this study is to identify and assess the genetic diversity of tilapia species present in Hawaiian streams. To accomplish this, more than 200 tilapia specimens were collected from ten wild populations across the islands of Maui, Molokai, Kauai, Oahu, and Hawaii. To date, sequence variation at the mitochondrial control region (mtDNA CR) has identified the presence of Sarotherodon melanotheron, Coptodon rendalli, and Oreochromis mossambicus x O. niloticus hybrids from six populations on Molokai, Hawaii and Oahu.

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