Does your fish burger contain mercury-tainted shark meat?
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A study of shark meat in Indonesia – the world’s largest shark fishery – has found dangerously high levels of mercury build-up in catches bound for overseas fish markets.
Research conducted at the Seafood Inspection Laboratory in Bali found that mercury concentrations in processed, export-ready shark tissue exceeded twice the commonly accepted safe consumption limit.
This is the first time that mercury levels have been tested in Indonesia-caught sharks bound for markets overseas, where importers and consumers are unaware that the fish that goes into fish burgers and fish and chips meals is shark.
Bull shark meat tested on 26 January 2017 was found to contain 2.431 parts per million (PPM) of mercury. The consumption limit for predatory fish species in key Indonesian export markets such as Australia, Singapore and New Zealand, and also Indonesia, is 1.0 PPM.
Bronze whaler meat – commonly sold as “flake” in Australia and cooked in batter for fish and chips dish- tested a week earlier was found to have a mercury concentration of 1.829 PPM.
Bull shark meat sourced from the same location just a year ago was found to contain a significantly lower concentration – 1.368 PPM.
Green School of Bali taking shark samples at Jimbaran fish market, Bali, Indonesia. Image: Bali Shark Rescue Center
“Consumers are being deceived and are unaware of the type of fish being sold and ultimately ingested,” commented Paul Friese, founder of Bali Shark Rescue Center, whose non-government organisation partnered with sustainability college Green School of Bali to conduct the study.
“Bull shark meat tested on 26 January 2017 was found to contain 2.431 parts per million (PPM) of mercury.”
In Indonesia, most sharks are harvested for their valuable fins and liver first, and those parts sold to specialist buyers. The animal is then skinned, beheaded and the meat is filleted and moved back into the fish market unmarked.
Shark fin can fetch up to IDR 2,500,000 (US$200) for a set, but locally sold shark meat sells for as little as IDR 25,000 (US$2) per kilo, and is used in street foods such as sate, fish cakes and meat balls. Overseas, shark meat is typically breaded and deep fried as fish burgers or used in the classic fish and chips dish.
The sale of shark meat is also masked by transshipping, the process of transferring fish caught at sea from ship to ship, which makes the source harder to trace.
Shark is particularly risky to eat because mercury bioaccumulates – the concentration of the heavy metal increases as it passes along the food chain, from plankton to shellfish, to small fish and onto larger predatory species.
Mercury has entered marine ecosystems as a result of discharge from coal-fired power stations, residential heating systems, waste incinerators and mining, and also from volcanic activity.
The main health risk from mercury consumption is damage to the nervous system. Unborn babies are particularly at risk from mercury pollution and, if exposed, may suffer impaired cognitive thinking, memory, attention, language, and fine motor and visual spatial skills in childhood.
Meanwhile, shark populations in Indonesia have been under increasing pressure, as more than three million sharks are killed every year for their fins alone. Sharks are a tempting target for fishermen, particularly in remote island areas where the fins of the predators can bring lucrative returns.
Questions & Answers
Q.Which specific shark species were found to have high mercury levels in the study?
Which specific shark species were found to have high mercury levels in the study?
Bull shark and Bronze whaler meat were tested and found to contain high levels of mercury. Bull shark tested at 2.431 PPM, and Bronze whaler at 1.829 PPM, both exceeding the 1.0 PPM safe consumption limit.
Q.What is the typical mercury consumption limit for predatory fish in key export markets like Australia and New Zealand?
What is the typical mercury consumption limit for predatory fish in key export markets like Australia and New Zealand?
The commonly accepted safe consumption limit for predatory fish species in important Indonesian export markets such as Australia, Singapore, and New Zealand, as well as Indonesia itself, is 1.0 parts per million (PPM).
Q.Why is shark meat particularly risky to eat regarding mercury contamination?
Why is shark meat particularly risky to eat regarding mercury contamination?
Shark is particularly risky to eat because mercury bioaccumulates, meaning its concentration increases as it moves up the food chain. This leads to higher levels of the heavy metal in larger predatory species like sharks.
Q.How do sellers mask the fact that fish products contain shark meat?
How do sellers mask the fact that fish products contain shark meat?
Sellers mask the sale of shark meat by filleting it after the fins and liver are removed, then moving it back into the market unmarked. Transshipping also obscures the source of the fish.
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