Mercury contamination in N.B. fish: what you need to know

Conservation Council reiterates recommendations presented to government following alarming study nearly two decades ago

A smallmouth bass caught, and released, in the Nashwaak River. Photo: Jon MacNeill/Conservation Council of New Brunswick

The Conservation Council of New Brunswick is concerned about recent news reports about the possible connection between eating local fish and the serious neurological health issues of one of New Brunswick’s sport fishermen.

As the CBC reported in late June, longtime angler David Addleman and his family doctor suspect fish caught and eaten from the Mactaquac Dam headpond are responsible for the mercury poisoning he was diagnosed with last year.

Addleman ate smallmouth bass from the Wolastoq (St. John River) at least once a week during the summer months, but stopped after neurological symptoms led to the discovery of three times the normal level of mercury in his blood. He suffers from neurological issues to this day.

The Conservation Council has examined the initial results of work conducted by Dr. Karen Kidd of the Canadian Rivers Institute that found high mercury levels in fish in the Mactaquac Dam head pond.

Mactaquac Provincial Park along the headpond. Photo: GNB Public Images Database

What’s the danger?

Mercury poses a serious health risk, whether it is airborne or concentrated in water. It is an especially severe risk to people consuming fish as recreational fishermen or traditional and/or mainstay sources of protein.

Mercury enters our lakes and rivers through natural sources such as flooded soil and head ponds (the element occurs naturally in our soil) and from sources like forest fires, burning coal, oil and gas, garbage incineration (especially if it contains high carbon content materials such as plastics), and mining. 

When mercury is deposited in water, it converts to methylmercury, a particularly toxic form of the element. When methylmercury is ingested it bio-accumulates, or builds up over time, in the tissues of animals and fish, eventually passing (and gaining in its toxicity) up the food chain to people. 

Mercury exposure in people can have fatal effects on the nervous, digestive and immune systems. This was recognized more than a century ago — it’s what came to be known as Mad Hatters’ disease because mercury was used to make felt for hats at the time. 

Fish-consuming wildlife such as loons, eagles and otters are also at risk from mercury contamination.

In 2000, the Conservation Council studied mercury levels in smallmouth bass and otter in the Wolastoq and found that mercury levels were 10 times higher than the maximum level recommended by the U.S. Environmental Protection Agency (the standard at the time, prior to Health Canada standards, set in 2005 and later approved by the Canadian Council of Ministers of the Environment (CCME)). 

Mactaquac generating station

What should be done?

The recommendations we made to the provincial government following our study more than 19 years ago are still important today and we repeat them here now:

  • Develop a comprehensive contaminants monitoring strategy including analysis of mercury in mammals, birds and fish (as well as human diet);
  • establish a database for chemical contaminants research for fish;
  • initiate child health studies, especially for populations which have high fish consumption throughout the province;
  • determine the level of public awareness of the provincial fish advisory,
  • carry out extensive fish monitoring for fish using both fillets and whole fish; and,
  • expand the river otter study to examine mercury levels in liver, brain and fur.

The Conservation Council advises recreational and sport anglers to exercise caution when eating fish caught in the Wolastoq near the head pond. Fishers should take time to understand the serious health risks associated with eating fish with high mercury levels. See Page 40 of this document for the province’s guidelines for eating brook trout, lake trout, landlocked salmon, smallmouth bass, perch, striped bass, catfish, pickerel and fresh water cusk caught in N.B. lakes and rivers.

We also call upon the provincial government to quickly address the issue of high mercury levels in fish by acting upon our recommendations, and to ensure the public is well informed about what is happening in the rivers, lakes and bays we love. 

Recommended links

Read our study (2000) on high mercury levels in smallmouth bass and otters in the Wolastoq (St. John River) 

Read the province’s guidelines for consuming fish caught in N.B. waters (Page 40)