Balancing the health benefits of fish with the risks of mercury exposure
For many in New Jersey, fishing is more than a pastime; it's a way to relax, connect with nature, and put a healthy, home-caught meal on the table. The state's extensive coastline and inland waterways offer an abundance of fishing opportunities. Yet, lurking beneath the surface of this idyllic picture is a hidden risk: mercury contamination. This toxic metal, which finds its way into our waters from industrial processes and other sources, can accumulate in fish to levels that may pose a serious health threat to those who eat them 3 . The challenge, however, is not to eliminate fish from our diets, but to learn how to navigate the waters of consumption wisely. This article explores the science behind New Jersey's fish advisories, empowering you to make informed decisions that balance the profound health benefits of fish with the very real risks of mercury exposure.
Mercury is a potent neurotoxin, meaning it can cause serious damage to the brain and nervous system 5 . The most common form of exposure for the public comes from eating fish contaminated with methylmercury, the organic form of mercury that builds up in the aquatic food chain 3 5 .
The process begins when mercury from natural and human activities enters water bodies. Small organisms and plants absorb it, and are in turn eaten by small fish. Larger, predatory fish then consume these smaller fish, leading to a process called bioaccumulation 4 . As a result, the largest and longest-lived fish—such as shark, swordfish, and tuna—tend to have the highest concentrations of mercury 1 4 .
The effects of mercury are not the same for everyone. Certain groups are far more vulnerable:
Their developing brains and nervous systems are most susceptible to damage. Exposure in the womb has been linked to impacts on cognitive thinking, memory, attention, and motor skills 5 .
Mercury can easily pass from a mother to her fetus or infant 4 .
Those who frequently eat high-mercury fish are at risk of accumulated exposure over time 4 .
To protect the public, state scientists continuously monitor contaminant levels in local marine life. One key study offers a perfect window into this process, focusing on a common recreational catch: flatfish.
Researchers hypothesized that flatfish, being bottom-feeders lower on the food chain, might have naturally low mercury levels, making them a safer choice for regular consumption 3 . To test this, they undertook a multi-year study from 2005 to 2008, collecting three species of flatfish—fluke (summer flounder), winter flounder, and windowpane—from various locations along the New Jersey coast.
Study examined mercury levels in three common flatfish species to determine their safety for consumption.
Over 450 muscle tissue samples were taken from fish caught by recreational anglers and research trawls 3 .
Skin was carefully removed to prevent contamination. Tissue samples were digested using ultra-pure nitric acid 3 .
Total Mercury was measured using a mercury analyzer. Selenium was analyzed by graphite furnace atomic absorption 3 .
Scientists examined differences between species, fish size, and geographical locations 3 .
The study confirmed that the three flatfish species generally had low mercury levels, but with important distinctions.
| Fish Species | Average Mercury (ppm, wet weight) | Average Selenium (ppm, wet weight) | Risk Level |
|---|---|---|---|
| Windowpane | 0.18 | 0.36 | Moderate |
| Fluke | 0.14 | 0.35 | Low |
| Winter Flounder | 0.06 | 0.25 | Low |
| Factor | Effect on Mercury Levels |
|---|---|
| Species | Levels vary significantly between different types of fish. |
| Size & Age | Larger, older fish of the same species have higher levels due to longer exposure. |
| Trophic Level | Predatory fish at the top of the food chain have the highest levels (bioaccumulation). |
The research also explored the protective role of selenium. Mercury binds to selenium in the body, potentially preventing it from interfering with essential selenium-dependent enzymes . A selenium-to-mercury molar ratio above 1:1 is thought to indicate a protective effect. While the average ratios for these flatfish were favorable, the study found significant variation among individual fish, suggesting this ratio is not yet a reliable standalone tool for consumer guidance .
| Material or Tool | Function in the Experiment |
|---|---|
| Muscle Tissue Sample | The tested material; represents the part of the fish humans consume. |
| Ultrapure Nitric Acid | Digests the organic tissue in the sample, releasing metals for analysis. |
| Microwave Digester | Uses controlled heat and pressure to rapidly and completely break down the tissue. |
| Cold Vapor Mercury Analyzer | Precisely measures the total concentration of mercury in the digested sample. |
| Graphite Furnace Atomic Absorption Spectrometer | Measures the concentration of selenium and other trace elements. |
So, what does this all mean for your next seafood meal or fishing trip? The science directly informs the practical advice issued by New Jersey's health and environmental agencies.
The New Jersey Department of Environmental Protection (NJDEP) publishes regularly updated guides like "Fish Smart, Eat Smart", which provide specific consumption recommendations for fish caught in state waters 1 2 . These advisories are based on the latest monitoring data and tell you which fish to limit and how often it is safe to eat them.
Before you head out, check the latest NJDEP advisory for the body of water you're fishing in 2 .
Don't consistently eat large amounts of a single species, especially larger predatory fish.
When possible, choose smaller, younger fish within the legal catch limits, as they have had less time to accumulate mercury 6 .
While cleaning and cooking fish can reduce other contaminants, it does not remove mercury from the muscle tissue 2 .
The presence of mercury in our fisheries is a complex issue, but it doesn't mean we have to abandon the tradition of eating fresh, local fish. Science provides a clear path forward. By understanding the risks, heeding the research-based advisories from New Jersey officials, and making informed choices about which fish to eat and how often, we can continue to enjoy the health and recreational benefits of fishing while safeguarding our well-being and that of our families. The goal is not fear, but empowered awareness—so you can fish smart and eat smart.
Fish Smart, Eat Smart