Climate crisis threatens access to nutrients in fish, study finds | Fish

The climate crisis and to a lesser extent overfishing could threaten the world’s supply of essential vitamins and minerals gained from fisheries, according to research.

Globally, 1 billion people rely on fish and seafood as their primary source of protein. Fish is also a key source of micronutrients – vitamins and minerals such as omega 3, calcium and iron – critical for the body’s health. A deficiency in these can cause a range of dangerous health conditions as well as reductions in energy levels and mental clarity.

Overfishing and the climate crisis are two of the most prominent threats to marine life, affecting the size, distribution and abundance of species globally. To determine how these growing pressures influence the nutritional contribution of global fisheries, an international team of researchers led by Lancaster University have combined data on the micronutrient content of species with a vulnerability index that indicates species susceptibility to climate change and overfishing. They apply these metrics to more than 800 fish species across 157 countries.

“When we look at the country level, climate change is the most pervasive threat to the supply of vital micronutrients, and in particular in the tropics,” said Dr Eva Maire, a senior research associate at Lancaster University and lead author of the study. Overall, the results showed that in just over 40% of countries studied, fisheries are highly vulnerable to climate change, threatening food security for millions of people.

The study, published in Current Biology, looked at five key micronutrients: calcium, iron, zinc, selenium and vitamin A. Unlike the clear impact of the climate crisis, they found that global fisheries have a relatively low nutritional vulnerability to pressure from overfishing.

“A key reason for why climate change is such a threat comes down to the species of fish that these countries are targeting as part of the catches,” explained Maire. There are differences in how nutrient-rich different fish species are, and vulnerability to climate change and overfishing varies considerably at the species level. The study found some species exist that are nutrient-dense and not very vulnerable to the impacts of climate change and overfishing, making them potential targets in fisheries management.

The climate is dramatically impacting and changing fisheries, but these are not currently being managed in a way that pays attention to the nutrients available, explained Prof Christina Hicks, Lancaster University environmental social scientist, who was also involved in the research.

“If we connect understanding [of nutritional needs in coastal populations] to what we know about what is available in the water, and how what’s available is likely to change, then we can pay more attention to fisheries being managed locally, through a nutrition-sensitive and the climate-sensitive lens,” she said.

Prof Jason Hall-Spencer, a marine biologist from the University of Plymouth who was not involved in the study, said one problem was the way international industrial fishing fleets plunder nutrition-rich tropical fisheries that might otherwise serve benefit local populations.

“Really the local population should be getting the nutritional benefits from those”, he said, but “they don’t have the large vessels that are required to catch those sorts of fish – they fish in a more artisanal way or in a way that’s got small boats”.

This was evident in the study, which showed a huge abundance of micronutrients were being caught off coastal waters of countries where diets are inadequate in those very same nutrients. “We identified this massive gap, or this inequity between who is catching the fish and who needs the fish, and that’s because you’ve got foreign fishing vessels – you’ve got demand for foreign income through trade,” said Hicks.