What is the MERCURY ISSUE all about?
The issue originally goes back to Japan, where between 1932 – 1968 (36 years) Chisso Corporation dumped an estimated 27 mt of industrial mercury compounds into Minamata Bay. Being as the main protein source for that community was seafood, and for two generations the peoples of the area daily consumed contaminated fish and other seafood hundreds of people eventually died and over 3,000 were recognized as having acute mercury poisoning, referred to today as Minamata Disease.
In another part of the world, Iraq, between 1971-72 industrial mercury was used as a fungicide to protect wheat from spoilage. From that specific event 459 people died and over 6,000 were hospitalized from consumption of the wheat. Since we have become aware of these disasters there has been a general global concern over mercury content, specifically in longer lived fish species.
Those species that have a higher than normal associated risk of problems with Mercury may include: King Mackerel, Shark, Sword Fish, Tile Fish, Sable Fish, and some Tunas essentially any long lived fish has the potential to accumulate Mercury through the food chain. Ongoing confusion between the issues of naturally and industrially occurring Mercury, the size, age, and harvest location of fish in these species has led to negative consumer reports and has generated fears in the general public and, unfortunately, resulted in people avoiding seafood as an excellent nutritional food choice that it is.
The focus of this article is to provide you with the most up-to-date, factual, information that hopefully, will allay those fears and allow people to understand the Mercury Issue as it relates to seafood’s, specifically Albacore Tuna. Fortunately, a number of very important studies have been carried to address the true impact of potential mercury consumption through fish. These studies are referred to below:
Faroe Island Study:
The Faroe Islands are an island group and archipelago under the sovereignty of the Kingdom of Denmark located about halfway between Norway and Iceland. The reason for this important study is that the main protein source of its people, traditionally, is seafood and the children in that environment were exposed neonataly to Mercury from their mother’s consumption of fish and whale meat. Given that whale meat has Mercury concentrations of > 4 ppm and the liver >1000 ppm the impact of such a diet was important to review (2007,EERC).
Through the results of this study the US Food and Drug Administration (USFDA) were able to determine the “lowest (mercury) level associated with adverse effects in people was 10 ppm. (10 parts of mercury per 1 million part of fish).
Seychelles Island Study:
The (Republic of) Seychelles are an archipelago of some 115 islands, under French Rule, located in the Indian Ocean about 1,500 kilometers of the east coast of Africa. Once again the populations of these islands consume about 10 to 20 times more fish than is common in Canada and the U.S. Specifically, the mothers tested in the study consumed fish on average 12 times a week, had Mercury hair levels averaging 6.9 ppm and no children born to these women showed any adverse effects from Mercury consumption.
As a result of such studies, and in order to provide firm guidelines related to the consumption of fish and seafood, the U.S., WHO (World Health Organization), British Food Standards Agency, United Kingdom, and the Canadian Government have identified the regulatory limits for Mercury in food at 1 ppm. Canada actually has a lower level of 0.5 ppm for total mercury from Canned Tuna – revised to 1.0 for frozen albacore.
Note: It should be noted here that the mercury in these studies was Man Made used in chemical processes and affected population of people in specific areas where contamination was an issue, and among a population that consumed 10 – 20 more fish and seafood then is common.
In Canada there has NEVER been any DOCUMENTED CASED OF MERCURY POISONING FROM FISH CONSUMPTION (EERC, 2007).
Let’s Talk Tuna
The general rule for all seafood’s is that the older the fish (shellfish) the more time in its life it has had to accumulate any metal in its environment, natural or man-made.
From the perspective of Tuna – raised levels of naturally occurring Mercury is recognized as a possible issue in older tuna i.e. some tuna, bluefin for example, may live up to 50 years and have reached weights of over 684 kg (1,500 lbs). Albacore Tuna typically live up to about 10-12 years.
We should be clear here what WE mean when we discuss TUNA for the purposes of this article is Canadian (American) caught Albacore Tuna (Thunnus alalunga). The reason we bring this up is that there are other species in some locations are mis-identified as Albacore, including;
- Blackfin tuna Thunnus atlanticus (albacore)
- Yellowfin tuna Thunnus albacares (albacore, autumn albacore, yellowfinned albacore)
- Yellowtail amberjack Seriola lalandi (albacore)
- Kawakawa Euthynnus affinis (false albacore)
- Little tunny Euthynnus alletteratus (false albacore)
Our Northern Pacific Canadian, as well as American caught, Albacore tuna leads a very interesting life. They spawn in the warm sub-tropical waters of Hawaii in the northeast to New Caledonia in the south west. In its first year of life the tuna hatchling will feed on plankton and then small fish growing to about 45-50 centimeters by the end of their first year. Albacore Tuna are open ocean fish; they never rest as they head generally east and arrive on the Pacific Coast of North America typically when they are about 3 years old.
They arrive around northern California and then swim north as the water temperature warms in the summer following their food as far North as Alaska. As the waters cool they retreat south and then head west, eventually to their spawning grounds.
Another point of clarification is that under a specific international treaty between Canada and the US there is allowed reciprocal Fishing for Albacore within each other’s territorial waters. Canadians fish Albacore in the US and Americans fish Albacore in Canada. The tuna are the same fish and are recognized by the nationality of the boat that catches them. So an albacore caught by a Canadian boat is a PRODUCT OF CANADA and vice versa. The statements made related to Mercury, and other issues, for the most part represent Albacore Tuna produced in Canada or the US.
Simply put the reason that Mercury is not an issue for Albacore Tuna caught in the coastal waters of the Pacific Northwest (Canada -US) is that the fish harvested in this area are typically 3 – 4 years old and weight approximately 3 to 11 kg (6.5 – 24 lbs.), they are too young to have accumulated any harmful levels of Mercury.
We should also point out that marine fish, like Northern Pacific Albacore have naturally high levels of SELENIUM. Selenium (Se) chemically binds to Mercury (Hg)
H2Se + MeHg = SeHg Thus making Mercury unavailable to cause harm.
This is another prime reason that naturally occurring Mercury in fish is not an issue. Due to this process, Selenium protects against Neurotoxity, Fetotoxicy, and Development Toxity and this activity has been shown in all investigated species of fish (2007, EERC)
Albacore Tuna In Canada
In order to begin to address the issue of Mercury in Albacore Tuna, the CANADIAN HIGHLY MIGRATORY SPECIES FOUNDATION (CHMSF-founded in 2002) undertook a preliminary testing of mercury samples from BC/Canadian Albacore Tuna in 2003. These few samples indicated the mean Mercury level in BC ALBACORE TUNA was 0.178 ppm which is significantly lower that the Canadian Standard of 0.5 ppm and the US Standard of 1.0 ppm.
Noting that the ongoing testing of BC/Canadian Albacore Tuna was “a good and the right thing to do”, at the direction of the CHMSF Board an ongoing Mercury Testing Program was initiated in 2003. In 2004 ongoing Mercury Testing became a permanent component of the CHMSF PLATINUM QUALITY ASSURANCE PROGRAM.
Canadian Mercury Test results IEC INTERNATIONAL (Collaborative Marine Research and Development Ltd.) on behalf of the CHMSF collected and retained samples of BC/Canadian Albacore Tuna harvested by the BC Fleet during the 2003 season. All samples were from Troll Albacore Tuna caught between Oregon and British Columbia and landed in Canada by the BC Fleet.
The samples consisted of a random combination of Frozen BC/Canadian Albacore – Tuna – Loin and BC/Canadian Albacore – Canned. Samples were submitted to CANTEST Laboratories, as a facility that is approved by the Canadian Food Inspection Agency for the testing of metals in seafood’s. The results from fish harvested in 2003, indicated that the mean Mercury content of the 25 fish tested, was 0.178 micrograms per gram (PPM) with a range of 0.087 to 0.307 micrograms per gram (PPM).
Results from this testing were well below the mandated levels regulated by the Canadian Food Inspection Agency of 0.5 pm and the US FDA regulation of 1.0 ppm.
Once again, IEC INTERNATIONAL (Collaborative Marine Research and Development Ltd.) on behalf of the CHMSF collected and retained samples of BC ALBACORE TUNA harvested by the BC Fleet during the 2004 season. All samples were from Albacore Tuna caught between Oregon and British Columbia and landed in Canada by the BC Fleet. The samples consisted of a random combination of Frozen BC/Canadian Albacore Tuna Loin hand BC/Canadian Albacore Canned.
Samples were submitted to CANTEST Laboratories, as a facility that is approved by CFIA for the testing of metals in fish flesh.
The results from the 100 fish sampled from the 2004 harvest indicated a mean Mercury content of 0.168 micrograms per gram (PPM) with a range of 0.017 to 0.278 micrograms per gram (PPM). Results from this testing were well below the mandated levels regulated by the Canadian Food Inspection Agency of 0.5 pm and the US FDA regulation of 1.0 ppm.
Table 2b.
Mercury Test Results from 2004 Fishery (Samples 49-100).
Mercury Test Results from 2005
Fishery
In 2005 the sampling continued on behalf of the CHMSF collected and retained samples of BC ALBACORE TUNA harvested by the BC Fleet. All samples were from Albacore Tuna caught between Oregon and British Columbia and landed in Canada by the BC Fleet. The samples consisted of a random combination of Frozen BC/Canadian Albacore Tuna – Loin and BC/Canadian Albacore Canned.
Samples were submitted to CANTEST Laboratories, as a facility that is approved by CFIA for the testing of metals in fish flesh. The results from the 38 fish sampled from the 2005 harvest indicated a mean Mercury content of 0.1567 micrograms per gram (PPM) with a range of 0.103 to 0.246 micrograms per gram (PPM). Results from this testing were well below the mandated levels regulated by the Canadian Food Inspection Agency of 0.5 pm and the US FDA regulation of 1.0 ppm.
Table 3 Mercury
Test Results from 2005 Fishery (Samples 1-38).
Where Are We Today?
Tuna landed by the Canadian /British Columbian fishing fleet is caught primarily in the eastern pacific regions along the west coast of North America ranging from Oregon to British Columbia. Results from our Studies, based on a total of 173 samples, conclude that the Average Level of Mercury in our North Pacific Albacore is 0.16 ppm.
Results from a US study carried out by Dr. Morrissey, University of Oregon; conclude that the average level of Mercury in North Pacific Albacore is 0.14 based on a sample size of 91 fish.
The CHMSF plans to maintain its Mercury Testing Program along with program components including the use of long line only, barbless hooks, bleeding, temperature control, blast freezing at sea, etc., all of which combined, are significant components of the CHMSF PLATINUM QA PROGRAM.
The CHMSF is pleased that our industry members are an integral part of the Mercury Testing Program and along with our colleagues in the US will maintain such programs.
What Others Are Saying About Canadian Albacore Tuna
HEALTH CANADA
Has revised its standards on Mercury levels in fish including: Fresh and Frozen Tuna, Shark, Swordfish, Escolar, Marlin, and Orange Roughy. Previous regulation, first established in 1970, focused on canned fish and set the regulated limit at 0.5 parts per million. This regulation is not changed. The new regulation is established for Fresh and Frozen fish at a limit of 1 part per million (ppm).
There remains some concerns over other fish such as Marlin, Swordfish, Escolar, Orange Roughy, and other species of Tuna. As a result the BC Ministry of Health does recommend limits on the consumption of these species. There are also 3 fresh water lakes have the potential for chemical mercury contamination and as a result there are warning about eating trouts and other species from those lakes (See BC Ministry of Health website).
BRITISH COLUMBIA MINISTRY OF HEALTH + BC CENTRE FOR DISEASE CONTROL revised, and upgraded, their recommendations in 2011 related to limits for consumption ttp://www.healthlinkbc.ca/healthfiles/hfile68m.stm
Starting: “Fish is part of a healthy diet. Fish provides many nutrients such as protein, while being low in saturated fat. Fish also provides healthy omega 3 fats, which are good for your heart and brain. Omega 3 fats are important especially for the brain and eye development of babies and children. Eating Well with Canada’s Food Guide recommends at least 2 servings of fish each week for children 2 years of age and older and for adults. Choose Fish Low in Mercury. One Serving is equal to 75 g (2.5 oz.) or 125 mL (1/2 cup)
However, after reviewing all of the data collected from our Canadian studies, and data from U.S. studies the BC Ministry of Health removed ALL LIMITS and warnings related to related to consumption of Albacore Tuna products caught in the CANADIAN fishery and labelled Product of Canada. Ie (from the BC Ministry of Health Website).
Note: Canned albacore tuna (labelled with ‘Product of Canada’) has no serving limits.
As an industry, we are pleased, and proud, that our Albacore Tuna has amongst the lowest mercury content of all Tunas. Albacore Tuna contains significant levels of Selenium, Omega-3 Fatty Acids, Protein, and other nutrients and as such should be, and is, an important component of our diets.
W. E. Lorne Clayton, RPBio., QEP, CC
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IATTC
Executive Director CHMSF