Study Shows Toxic Metals in Hudson River Striped Bass Decreased Over Decades

A fish scale analysis suggests improved water quality and provides a basis for a non-lethal method of measuring toxic metal accumulation

STONY BROOK, NY, May 15, 2026 - Striped bass are a popular and often human-consumed commercial and recreational game fish. Trace elements or metals essential for life are in these fish and other eatable fish, as well as nonessential and toxic metals such as mercury, lead, and arsenic. A study led by researchers in the School of Marine and Atmospheric Sciences (SoMAS) at Stony Brook University used fish scales from striped bass to assess the accumulation of toxic metals in these fish. They found that the concentrations of most toxic metals generally reduced over time, yet, with exceptions.

Magnified view of the type of archived small fish scales used in a study to detect concentrations of toxic metals in Hudson River striped bass from the period 1989 to 2017.
Credit: Chen Lab, SoMAS

All fish scales collected occurred from 1989 to 2017 in the Hudson River Estuary (HRE), which runs from the New York Harbor to upstate New York. The collection was part of the Hudson River Biological Monitoring Program (HRBMP), a finfish monitoring program that began in the 1970s and was designed to address concerns about the effects of river water from power plants on fish populations. The research team's findings are detailed in a paper published in the Canadian Journal of Fisheries and Aquatic Sciences.

Scales were removed from the fish, which were then placed back unharmed into the water. A standard scale removal, selection and evaluation process analyzing chemical composition was used with the archived scales. A total of 23 trace metals were measured across 103 samples from striped bass of various sizes and ages spanning 0 to 9 years. Samples were analyzed for trace elements using Inductively Coupled Plasma Mass Spectroscopy. The researchers used statistical models accounting for fish age and body size to evaluate long-term temporal trends in metal concentrations.

Overall, they discovered significant declines in toxic metal concentrations in the fish over time. This, the authors say, occurred to a degree where "this study establishes a baseline time series of relative trace element contamination in the study area, suggesting potential improvements in regional water quality and demonstrating the utility of fish scales as indictors of environmental recovery and the effectiveness of long-term pollution control efforts in the lower HRE."

Some of the key findings include:

• Larger striped bass often had lower concentration of toxic metals than stripers over the study period.

• Smaller fish tended to have slightly higher toxic metal concentrations.

• Mercury, a toxic metal that the New York State Department of Health identifies in many consumed fish and is harmful to health, displayed the strongest and most consistent declining trend in striped bass.

• Across all years, arsenic, lead, and mercury were detected consistently, with concentrations showing moderate interannual and fish size-related variations.

"There was one surprising result in that arsenic, which is very toxic, showed an increase in concentration over much of the study period," says Yong Chen, PhD, senior author, a Professor in SoMAS, in the Institute for Advanced Computational Science at Stony Brook, and Director of the Chen Lab. "But we are not sure if the fish themselves actually retain arsenic, which may originate from natural geologic sources within the watershed, making its environmental dynamics more difficult to manage than pollutants primarily associated with human activities."

Striped bass of various ages and sizes, similar to this one from the Hudson River, were used in the research to access toxic metal concentrations in fish over time.
Credit: Sarah Praisner

Chen believes that the fish scale assessment method is an efficient, novel and responsible way to gauge toxic metal concentrations in striped bass and other fish, and one that does not kill or even harm fish. He also thinks that combined with other environmental analyses and water quality assessments, the method is an important way of potentially monitoring the water quality of the Hudson and other similar estuaries.

One problem in using fish scales to assess trace element concentrations over time is that researchers need to know if fish species are local to the waters or not. Chen stresses that fish move around, migrate, and move fast, and for fish that are mostly only moving through the HRE for example, they may not have as much continued exposure to trace elements present compared to native species to the river. Therefore, scale assessment may not be a fully accurate presentation of toxic metal concentrations in some fish.

Chen says the research team needs to do the same research with a larger sample of fish scales from the archive to further advance the work. Additionally, they will analyze scales from other species in the HRE, such as Tomcod, Anchovy, American Shad, and White Perch, to see if the same trend of reduced concentration of toxic metals exists in these species.

The HRBMP data was gifted to Stony Brook University by the Entergy Corporation in 2019. It is known as the Hudson River Collection. SoMAS has housed thousands of fish and other biological samples from the collection since the inception of the gift. The work demonstrates the long-term scientific value of archived biological collections and monitoring programs such as HRBMP, which can provide critical insight into environmental change and ecosystem recovery over decades.