The impact of heavily polluted estuaries on predatory fish

Bluefish (Pomatomus saltatrix). Credit, NOAA.If you fish from urbanized estuaries in New Jersey, you should probably avoid eating what you catch.

A new study from the journal Estuaries and Coasts looks at young bluefish and their prey from bays in New Jersey to better understand how pollutants make their way up the food chain and affect fish behavior.

The researchers conducted a laboratory experiment in which they took young bluefish from the relatively clean Great Bay near Tuckerton and fed them with common prey fish, menhaden and mummichog, taken from the same site as well as the more heavily polluted Hackensack River estuary.

Surrounded by a highly industrialized region near New York and encompassing several sewage treatment plants and landfills, the Hackensack River has endured a long history of contamination, though water quality has improved somewhat in recent years.

Not suprirsingly, the researchers found that "bluefish fed Hackensack River prey and the Hackensack River prey themselves had significantly elevated concentrations of PCBs, pesticides, and total mercury compared to Tuckerton counterparts."

The researchers also found that the exposure to contaminants had serious impacts on fish growth and behavior. Bluefish fed contaminated prey for 4 months exhibited decreased feeding and spontaneous swimming. They also were smaller.

Interestingly, the study showed that bluefish fed prey from the relatively clean estuaries also accumulated pollutants over time and the effects were biomagnified from prey to predator for both groups.

For example, bluefish fed prey from the Hackensack River accumulated PCB levels far above USDA guidelines and 7 times greater than the prey themselves. Meanwhile bluefish fed prey from Tuckerton accumulated PCB levels 10 times greater than the fish they ate.

This clearly is a public health concern given that bluefish is a widely consumed fish. This could be problematic for the bluefish population given that juveniles spend the early part of their life in mid-Atlantic estuaries. 

The authors write, "Alterations of bluefish behavior and growth from exposure to contaminants may have detrimental effects on migration, overwinter survival, and recruitment success."

However the researchers also recomend that studies be conducted in the estuaries themselves to confirm that the impacts they observed transfer to the field setting.

--by Rob Goldstein

Candelmo, A., Deshpande, A., Dockum, B., Weis, P., & Weis, J. (2010). The Effect of Contaminated Prey on Feeding, Activity, and Growth of Young-of-the-Year Bluefish, Pomatomus saltatrix, in the Laboratory Estuaries and Coasts DOI: 10.1007/s12237-010-9292-3