Levels of mercury in fish landed in Ireland are very low and fish is safe for consumption by the general population, latest available data finds.

This will be “comforting for the Irish seafood industry and consumers alike”, Prof Ronan Gormley of University College Dublin’s (UCD) school of agriculture and food science says.

Writing in UCD’s SeaHealth e-bulletin, Prof Gormley explains that a monitoring programme was put in place for fish landed at major Irish fishing ports in response to the introduction of maximum limits for mercury in fishery products in 1993.

The monitoring by Ireland’s Marine Institute has found that mercury levels of fish and shellfish landed at Irish ports are low and “well within the EU human-consumption tolerance level”.

“However, these catches do not include deepwater species such as shark, swordfish, marlin and tuna,” Prof Gormley notes.

Mercury is a naturally occurring heavy metal found in air, water and soil, but mercury from industrial centres can travel miles before “raining into the ocean in organic form as methyl mercury”, he explains.

“Fish become contaminated, leading to public health concerns about different species and their mercury levels,” he notes.

In 2004 the EU Commission asked the European Food Safety Authority to consider data collected by member states.

It published its opinion, with emphasis on mercury intake from fish by vulnerable groups such as women of childbearing age, breastfeeding women and young children to raise awareness in all national authorities with responsibility for public health.

Prof Gormley notes that large, predatory fish such as shark, tarpon, swordfish and tuna accumulate higher levels of mercury over a long lifetime.

“These species are often migratory, and it is not possible to exclude fish from particular waters where background levels of mercury contamination might be high,” he says.

However, data shows that EU consumers who eat average amounts (300-350g a week) of fishery products are not likely to be exposed to unsafe levels of methylmercury.

Consumers who eat a lot of fish may be at higher risk, but at time of issue of the EC note (2004) there was insufficient data to specify the situation in all member states.

Maximum levels of mercury in fish were amended in 2022, he notes.

Levels were lowered for cephalopods (eg, squid, octopus, cuttlefish, nautilus) and marine gastropods (eg, abalone, conches, periwinkles and whelks) to 0.5 or 0.3mg/kg. Levels in shark, swordfish, pike and tuna were maintained at 1mg/kg.

Consumption of shark, swordfish, marlin and fresh tuna in Ireland is relatively low, apart from canned tuna which is increasing in popularity.

Latest advice is that pregnant or breastfeeding women and young children should not exceed two 226g cans a week.

Other adults and young people should continue to eat tuna and fish products as components of a healthy diet, Prof Gormley says.

Mercury levels of fish and shellfish landed by fishing boats at Irish ports are low and well within EU guidelines for human consumption, as underscored by a recent briefing from UCD’s Institute of Food and Health.

However, as Derek Evans says in his Angling Notes for The Irish Times this week, these catches do not include deep-water, often migratory species such as shark, swordfish and tuna — the latter of which is being consumed in Ireland increasing quantities in its canned variety.

It’s advised that young children as well as pregnant or breastfeeding people limit their intake to two 226g cans of tuna a week as a precaution.

But the science experts adds that the general population need not fear any fish products as part of a healthy balanced diet.

The Irish Times has more on the story HERE.