Gone (safely!) fishing in the River Raisin
Common Carp, by Alexander Francis Lydon, public domain image. There are 4 types of invasive carp found around the Great Lakes. Michigan is actively using new technologies to keep them out of the local waterways and no invasive carp have been found in the River Raisin, only the native common carp. Because of pollution, even relatively far upstream in Manchester, you should limit your consumption of carp from the Raisin!
by Claire Pajka
The River Raisin is a popular place for water recreation like canoeing and fishing, and though many fish like rock bass and smallmouth bass can be caught and enjoyed, you should take care when consuming fish from the Raisin.
In 1987, the Southeast portion of the River Raisin was designated by the EPA as an area of concern due to pollution from agricultural and landfill runoff, a wastewater treatment plant, and power plants near the river. This pollution greatly increased concerning contaminants like polychlorinated biphenyls (PCBs) and heavy metals including copper, zinc, and chromium, which are known to bioaccumulate in fish.
Bioaccumulation occurs when the body has a difficult time metabolizing a harmful substance, and ultimately ends up accumulating this substance at a rate faster than the body can degrade or eliminate it. Certain fish store high levels of contaminants – like heavy metals – within their bodies and pass these pollutants to humans and animals when they are consumed, which can cause devastating health consequences as the body continually struggles to eliminate these contaminants. Consumption of fish with disregard for heavy metals like copper and chromium is linked to eventual negative health outcomes such as renal failure and liver damage. According to the Michigan Department of Natural Resources, mercury and PCBs are among the biggest threats to human health from consuming fish from the River Raisin.
Mercury, though a naturally occurring element, is often released from smokestacks of coal-fired power plants, and can be detrimental to brain development in children and heart function in older adults. PCBs were used in electrical equipment and found in hydraulic oils, and have been linked to the development of cancer and diabetes, as well as atypical brain development in children.
But just where are these PCBs in the fish coming from? Decades of negligence from industrial factories and paper mills along both the main and south branches of the river, as well as dams collecting sediments, have caused the water in the Raisin – especially near Monroe – to be almost uninhabitable for fish. Though levels of PCBs were not as high in the main branch as in the southern branch of the Raisin, they were still found to collect to startling levels in certain fish species.
Manchester itself lies on the main branch of the River Raisin, upstream from both Dundee and the Winchester Bridge in Monroe. Along the section of the main branch near Manchester, carp are the only fish that consumers need to monitor, as the level of PCBs has resulted in a recommended consumption limit of six servings per year. Carp in the South Branch of the River Raisin contain an even higher amount of PCBs than in the main branch, and should not be consumed more than twice a year. PCBs have an affinity for clay and collect in the sediments at the bottom of the river, which doesn’t fare well for bottom feeding fish like carp who prefer to stay close to the riverbed. By spending most of their time among the contaminated sediments, carp can pose a more significant threat to human health from consumption than other fish.
Those fishing in the south branch should also watch consumption of suckers, who contain a high level of mercury. For suckers under 13 inches, one serving per month is the recommended limit, while the limit for suckers over 13 inches is six servings per year. The MDNR recommended serving sizes are based on the weight of the person consuming the fish: serving size for a 45 pound, 90 pound, and 180 pound individual is two ounces, four ounces, and eight ounces, respectively.
If you fish downstream of Dundee Dam, the safety recommendations become a lot more lengthy. Carp continue to be an issue because of PCBs, and it is recommended that carp of any size are never consumed if caught below the dam because they contain a level of PCBs that could lead to health problems even after just one meal! The list of “Limited Consumption” – meaning that consumption should not exceed two times per year – because of PCBs continues with catfish, freshwater drum, largemouth bass, smallmouth bass, and white bass. However, the ‘less than twice a year rule’ for limited consumption has a few exceptions: Michigan Department of Health and Human Services explains that if you are under the age of 15, have health problems like cancer or diabetes, or are pregnant or planning on having children in the next several years, all fish on the “Limited Consumption” list should be avoided completely. For rock bass caught below the Dundee Dam of any size, the recommended serving limit is four per month due to high levels of mercury.
Fishing areas for the River Raisin all require a fishing permit that may be purchased through the DNR, and are $26 annually, or $10 a day. More information on general fishing regulations – such as appropriate size and daily catch limits – can be found on the DNR website here. In order to safely consume fish from the Raisin, though, fishermen should reference the Michigan Safe Fishing Guide in order to protect themselves from contaminants lurking within certain fish.
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