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Bay Blog: perch


White Perch in the Bay and its Rivers

In recent years, people have become increasingly concerned about the issue of toxic materials, like Polychlorinated Biphenyls (PCBs), contaminating fish and shellfish in water bodies around the world. In the Chesapeake Bay region, the Bay states have issued fish consumption advisories throughout the Bay and its rivers to protect the health of people who enjoy dining on the Bay's fish and shellfish.

One way that Bay scientists assess how toxic pollutants are affecting the animals and plants in the region, Bay Program partners have focused on PCB concentrations in local white perch. PCBs are persistent organic chemicals that were formerly used in industrial practices in the United States. They enter the environment and can impact the creatures living within it. Although PCBs are not the only contaminants in an area, PCB concentrations in white perch provide an indication whether other chemical contaminants are present in an area.

Why did the scientists select white perch?

White perch are a good indicator of toxic contaminant concentrations in the Bay's waters because they are a resident species in the Bay; the majority of white perch remain in local waters throughout their lives. Considered an enjoyable fish to eat, white perch are a commercial and recreational fishery in the Bay. For scientists who are examining the effects of chemical contaminants on fish, as well as the impact on humans who eat PCB-contaminated fish, white perch are a logical species to study.

What does the research show?

Data gathered from Maryland and Virginia suggests that PCB concentrations are higher among white perch in the upper Bay than they are in the lower Bay. Similarly, there is a trend in fish tissue where fish on the eastern shore have lower concentrations of PCBs than their counterparts on the western shore.

A common characteristic among the areas of the Bay where white perch have higher PCB concentrations is related to land development; the western shore of the Bay is more developed than the eastern shore of the Bay, and white perch from the Bay's western shore have higher PCB concentrations than their counterparts on the eastern shore. Additionally, white perch sampled from the Patapsco River had particularly high PCB concentrations, which can be attributed to the level and type of industrialization in the Baltimore area.

What does this mean for someone fishing for white perch in the Bay?

Many of the Bay's waters have active advisories for limiting the consumption of white perch. As is true with any fish, it is important for someone who plans to catch white perch in the Bay's waters to first check out the fish consumption advisories to see what the state recommends regarding consuming fish caught in the Bay and its rivers.

What is the future of PCBs in the Bay?

Without sufficient data to determine a trend in the PCB concentrations in white perch in the Bay, Bay scientists cannot say for sure what to expect regarding the future of those toxic contaminants in white perch in the Bay. However, PCBs were banned more than 25 years ago, so scientists expect to see a natural decrease in their concentration in white perch over time.

What is toxic pollution and how does it impact the Bay?

Chemical contaminants that get into the environment and harm the animals and plants around them are typically considered to be toxic pollution. Learn about toxic pollution in the Bay.

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