Coastal Fish Tissue Contaminants

Contaminants in fish not only affect the fish’s own health and ability to reproduce, but also affect the many species that feed on them. Contaminants also may make fish unsuitable for human consumption (U.S. EPA, 2000).

This indicator, derived from an indicator presented in EPA’s fourth National Coastal Condition Report (U.S. EPA, 2012a), is based on the National Coastal Assessment (NCA) fish tissue survey data from 1,623 stations throughout the coastal waters of the United States. The survey was designed to provide a national picture of coastal fish tissue contaminants by sampling sites in coastal waters of the contiguous 48 states as well as Southeastern Alaska, American Samoa, and Guam. Each site was sampled during the summers of 2003 through 2006.

Fish and shellfish analyzed in the survey included demersal (bottom-dwelling) and slower-moving pelagic (water column-dwelling) species (e.g., finfish, shrimp, lobster, crab, sea cucumbers) that are representative of each of the ecoregions (Northeast Coast, Southeast Coast, Gulf Coast, West Coast, Southeastern Alaska, American Samoa, and Guam). Whole-body composite samples (typically 4 to 10 fish of a target species per station), as well as fillets, were analyzed for a suite of contaminants, including metals, pesticides, polychlorinated biphenyls (PCBs), and polycyclic aromatic hydrocarbons (PAHs).

To determine the fish tissue contaminant index, contaminant concentrations in fish tissue were compared with established EPA risk-based advisory guidance values, which were available for 16 analytes (U.S. EPA, 2000). The NCA used these advisory guidance values as surrogate benchmark values for fish health because comprehensive ecological thresholds for contaminant levels in juvenile and adult fish do not exist. Their analysis is an ecological assessment of the potential exposure of fish populations to biologically available contaminants in the environment.

For this indicator, a site was given a high contamination score if one or more contaminants were present at a concentration above the guidance values. A site was rated moderate if one or more contaminants were within the guidance values range but none was in exceedance. Sites with all contaminants below their guidance values were given a low contamination score.

Nationwide, 74 percent of sites showed low fish tissue contamination, 13 percent had moderate contamination, and 13 percent exhibited high contamination (U.S. EPA, 2012a). Fish tissue contamination varied from one ecoregion to the next (Exhibit 1). For example, the percentage of sites with low contamination ranged from 60 percent in the Northeast Coast to 100 percent in Guam. With the exception of the Northeast Coast, all other ecoregions had less than 10 percent of sites with high contamination.

• The indicator is limited to coastal samples, and does not include data from Southcentral Alaska, Hawaii, or the Caribbean territories, which had not been assessed at the time this indicator was compiled.
• The data are not broken out by trophic level of the fish and shellfish species, which influences bioaccumulation of contaminants.
• Whole-body contaminant concentrations in fish overestimate the risk associated with consuming only the fillet portion of the fish, with the exception of mercury and cadmium, which are generally underestimated.
• No EPA guidance criteria exist to assess the ecological risk of whole-body contaminants in fish.
• Samples are collected during the summer, and the indicator is only representative of this time period. It is unlikely, however, that contaminant levels vary substantially from season to season.
• There are no trend data for this indicator.

This indicator is based on an analysis published in EPA’s fourth National Coastal Condition Report (U.S. EPA, 2012a). The NCA data are housed in the National Coastal Database (U.S. EPA, 2012b) (https://www.epa.gov/national-aquatic-resource-surveys/data-national-aquatic-resource-surveys).