Irish commercial fishing magazine The Skipper has published a detailed policy analysis demonstrating that the contested carbon methodology underpinning a widely reported European study overestimates trawling’s carbon impact as much as a thousand-fold, and that Ireland’s own fleet is among the most carbon-efficient in the world.
This is a major analysis of a peer-reviewed paper claiming that bottom trawling in EU, UK and Norwegian waters imposes up to €16 billion in social costs annually. The article, Built on Sand: The €16 Billion Trawling Study That Does Not Add Up, finds that the study’s central claims rely on a carbon model that has already been formally rebutted in the pages of Nature – and this new paper uses the same discredited inputs without adequate disclosure.
The study, Bottom Trawling in Europe’s Waters Costs Society up to €16 Billion Annually — Mostly Due to Climate Impacts published in Ocean and Coastal Management and promoted by National Geographic Pristine Seas, claims that 120 Irish-flagged bottom trawlers cost Irish society up to €628 million a year, and that 546 UK vessels impose up to €1 billion in annual costs.
These are figures that have since been cited in media coverage and submitted as evidence to policymakers ahead of the UN Ocean Conference.
The Skipper’s analysis finds that the headline figures are almost entirely driven by a sediment carbon model developed by co-author Dr Enric Sala in 2021, a model subsequently rebutted by Professor Jan Hiddink of Bangor University and colleagues in a formal response published in Nature in May 2023.
Hiddink et al. identified that the model’s core assumptions about how quickly disturbed seabed carbon breaks down were wrong by a factor of between 100 and 1000. Independent biogeochemists, including Dr Gordon Holtgrieve of the University of Washington and Dr Jack Middelburg of Utrecht University, have described the original model’s assumptions as indefensible.
Once the contested sediment carbon figures are stripped out, the €16 billion headline collapses entirely.
BIM’s own 2023 Carbon Footprint Report of the Irish Seafood Sector found that the Irish fishing fleet emits on average 1.03 tonnes of CO2 equivalent per tonne of fish landed – well below the global seafood average of 1.7 tCO2 eq. per tonne, and lower than most other animal food production.
Total greenhouse gas emissions from the entire Irish seafood sector, covering both wild capture and aquaculture, were measured at 396,207 tonnes of CO2 equivalent. The Pristine Seas model’s lower-bound sediment carbon cost for Ireland alone exceeds one-third of that real total, based on k values leading experts say are wrong by three orders of magnitude.
The article also documents factual inconsistencies in the study’s press materials, including a 20% inflation in a key size comparison between two press releases issued six weeks apart, and a ten-percentage-point unexplained jump in a headline MPA overlap figure between versions of the same paper. It further highlights a conflict-of-interest concern: the new paper’s lead funder and co-author is the originator of the 2021 model on which it depends, and the paper declares no competing interests.
‘Irish and British fishermen deserve better than policy decisions driven by a headline figure that rests on a carbon model leading experts have already declared wrong by a factor of 1000,’ said The Skipper’s editor Niall Duffy.
‘The Skipper is publishing this analysis because someone has to ask the questions the press release was designed to prevent.’
He commented that The Skipper’s analysis concludes that well-managed bottom trawl fisheries, including those operating in Irish and British waters, can produce some of the lowest-carbon protein on earth, and that the appropriate policy response to the documented challenges facing European demersal fleets is better fisheries management, not elimination based on figures experts describe as astronomically wrong.
