ICES has revised its estimate of the North Atlantic mackerel stock, showing it was far larger than previously believed.
The claim is made in an opinion article by Icelandic MP Sigurjón Þórðarson, who says the gap between the 2023 assessment and the revised 2025 figures runs into several million tonnes.
The article was published as coastal states are finalising new mackerel fishing agreements. Þórðarson argues that quota talks rest on uncertain and unstable advice and should therefore be handled with caution.
Opinion: the stock is far larger than assumed
In the article, Þórðarson writes that the ICES reassessment shows the stock was “much larger than previously thought”. He adds that the difference between the 2023 estimate and the corrected figures amounts to “many million tonnes.
He says this does not surprise those who have followed the advice in recent years. According to the author, the stock estimate rests on a weak foundation, based in part on surveys conducted only every few years.
The author says the mackerel was not overfished
Þórðarson draws two main conclusions. First, he writes that mackerel was never overfished, despite repeated claims to the contrary. Using ICES’ own reference points and the revised data, he says the stock was instead underused by more than 1.4 million tonnes at its peak.
Second, he notes that the stock declined rapidly after 2014 despite this underuse. This, he writes, shows that “the impact of fishing on the mackerel stock has been greatly overstated”.
Call for caution in quota talks
Þórðarson, who is chair of the Icelandic parliament’s industry committee, calls the advice behind quotas “based on guesswork”. He urges governments to treat future ICES advice critically and to rely more on direct indicators, such as fish condition, rather than stock counts alone.