OHA decreases recommended meal allowances for people who eat Columbia Slough resident fish

December 11, 2019

The Oregon Health Authority is changing its recommendation on the amount of resident fish from the Columbia Slough that people should eat. An OHA advisory for species in the slough was last updated in 2010.

Fish tissue data collected by the City of Portland shows the level of polychlorinated biphenyls, or PCBs, and mercury found in resident species in the slough warrants updating meal recommendations, according to public health officials. The slough extends northeast from the Willamette River near Sauvie Island south and east to the mouth of Fairview Lake.

The advisory changes the meal recommendations from two fillet meals per month to one fillet meal per month for all resident fish and crayfish, except for largescale sucker, which remains at two fillet meals per month. The change in meal recommendations should be followed by everyone.

Meal Recommendations for Resident Fish and Crayfish in the Columbia Slough

Advisories are issued when fish or shellfish tissue data verify that the level of a contaminant -- in this case, PCBs and mercury -- are above Oregon’s established health-based screening values. Meal recommendations are then calculated using these data to help people better understand the amount of resident fish and shellfish they can safely eat in one month.

Resident fish such as carp, black crappie, bluegill, largemouth bass, largescale sucker and sunfish live in the same area their entire life. Some, like bass, are long-lived top predators, eating other PCB-contaminated fish within the slough. The longer they live, the more PCBs they accumulate. Other fish, such as carp, are bottom-feeders. PCBs can accumulate in these types of fish because they live and eat in areas where PCB concentrations tend to be elevated.

This advisory does not apply to migratory fish like salmon, steelhead and shad that spend most of their lives in other places beyond the slough that are not land-locked. These and other migratory fish are a healthy choice when considering what fish to eat.

People who eat too much resident fish and shellfish contaminated with PCBs and mercury can suffer negative health effects over time. These health effects include damage to organs, the nervous system and the brain, leading to potential learning and behavior problems. Mothers can pass PCBs to their babies during pregnancy or in breastmilk, so fetuses, babies and small children are most vulnerable to the health effects of PCBs and mercury.

While it is important for people to know about contaminants in fish and shellfish, it is equally important to continue to eat at least two meals of a variety of fish per week to gain important health benefits. Fish are high in protein, low in fat, and rich in nutrients like omega-3 fatty acids. Omega-3s provide protection from heart disease and are an important brain food for adults, children and fetuses.

Part of the Department of Environmental Quality’s Columbia Slough clean-up plan includes periodic fish tissue sampling to monitor the recovery of the Slough. The City of Portland’s Bureau of Environmental Services implements the periodic sampling. As the monitoring data becomes available, OHA evaluates and updates the advisory meal allowances as warranted.

Long-term fish tissue and sediment monitoring data collected over the past 25 years by the city indicates most contaminant concentrations are decreasing and that PCB concentrations are slightly decreasing or stable. However, OHA is using an updated method for calculating meal recommendations and additional fish tissue data that improves the accuracy of the Columbia Slough advisory. OHA also recently updated a Lower Willamette River advisory and considered that information because the two water bodies are close to one another.

For a list of other areas and water bodies with existing fish advisories and recommended meal allowances, visit the OHA fish advisory webpage.