Cultured Fish as Biological Indicators of Pollution

Environmental pollution has been long recognized by the Department of Defense as a serious issue for human health and safety, natural resource protection and biodiversity, and because of severe economic and commercial impacts.

Chemical contaminants found in Pearl Harbor have led State of Hawaii, U.S. Navy and other federal officials to notify the public and issue warnings to alert fishermen not to eat any fish caught in the harbor. Though most of the contaminants found in the harbor have been banned, and a number of environmental remediation projects have been conducted, many of the chemicals may persist for decades, making fish caught there unsafe for eating at any point in the near future.

The Oceanic Institute conducted the project, ?Cultured Fish as Biological Indicators of Pollution,? as an innovative approach to assessing aquatic pollution at affected defense sites and the effectiveness of remediation efforts. Funding was provided by a grant from the Center of Excellence for Research in Ocean Sciences (CEROS).

Methods and technologies in the project will provide a model for remedial assessments at Pearl Harbor and similarly affected sites. Through the use of fisheries stock enhancement technology developed by OI, the project developed and tested the use of hatchery-raised fish as indicators of environmental pollution.

Using two indigenous species, the Pacific threadfin (locally known as moi) and striped mullet, the cultured (or ?clean?) fish were identified with binary-coded tags and released into harbor waters. Periodically over more than one year, the released fish were recovered and evaluated for the presence and concentration of organochlorine pesticides through direct chemical analysis of whole body samples.

Five organochlorine pesticide compounds were detected in fish tissues: chlordane, DDT, DDD, DDE and dieldrin. In general, the weight of compounds found in the body increased with time at large and body size, while the concentration of compounds (weight per unit weight of fish) decreased, suggesting that compounds were sequestered in particular organs rather than within the fish as a whole.

The results of this project successfully demonstrated the key issues: cultured fish could be raised, tagged, released into Pearl Harbor and recaptured up to one year after release, and cultured fish showed systematic but highly variable uptake of five organochloride compounds into tissues.

The results support the feasibility of the concept as a tool for monitoring potential environmental impacts of polluted Department of Defense sites.