Fishing and climate change: what are the impacts on carbon sequestration in the ocean?

[Press release] - Published on October 30, 2025 in Press Room, Science-Society

An international team led by researchers from the University of Montpellier, the CNRS, the World Maritime University (WMU), and the University of California has quantified the past, present, and future impact of fishing and climate change on the ability of commercially important species (fish and other macroinvertebrates) to sequester carbon at the bottom of the ocean. Their findings, published in the journal Nature Communications, show that climate change is expected to reduce carbon sequestration by commercial species by 13.5% by the end of the century. However, the impact of climate change remains much lower than that of fishing, which has already reduced carbon sequestration by 47% compared to 1950. This research therefore calls for more sustainable ocean management that takes into account the impact fishing can have on carbon sequestration.

What if marine macrofauna could help trap more carbon?

Natural Solutions for Climate (NSC) have the advantage of killing two birds with one stone: limiting climate change while combating biodiversity loss through the restoration, protection, or improved management of ecosystems such as forests. But at a time when forests are burning, the scientific community is gradually turning to the ocean to find new NSCs. In their joint 2021 report, experts from the IPCC and IPBES suggest that the way we manage the food resources provided by the ocean must evolve in order to help us combat climate change. But what is the link between a biodiverse ocean, fishing, climate change, and carbon sequestration? These are the questions that this new study attempts to answer.

How does marine macrofauna sequester carbon?

The role of fish and macroinvertebrates (macrofauna) is far from negligible, given that they are responsible for 30% of the carbon trapped by all marine organisms. Their diet, composed of carbon, is partly accumulated in their flesh or expelled via fecal pellets. When macrofauna produce fecal pellets, die of disease or old age, the carbon they contain sinks to the ocean depths, trapping the carbon they contain. The study shows that in 1950, before the combined effects of fishing and climate change emerged, commercially important macrofauna had the capacity to trap 0.23 billion tons of carbon per year, 90% of which was via fecal pellets.

The historical impact of fishing

Today, this commercially important macrofauna traps only 0.12 billion tons of carbon per year, down 47% from the 1950s. "Every time fishing reduces the biomass of commercial species by 1%, carbon sequestration will decrease by 0.8%," the study's authors explain. Fishing has a greater impact on carbon sequestration through the sinking of carcasses than through the sinking of fecal pellets. "This is because fishing targets the largest organisms, which are the most likely to die of old age. In addition to the impact this may have on carbon sequestration, this reduction in the arrival of carcasses on the ocean floor also means a reduction in the arrival of food in the abyss, as carcasses are a delicacy for the organisms that live there. "So we may be starving a whole host of deep-sea organisms that we know very little about," they conclude.

Impact of climate change: the snake that bites its own tail

The more climate change worsens, the lower the capacity of commercial species to sequester carbon will be, which exacerbates global warming. If the Paris Agreement is respected (+1.5°C), sequestration will decrease by 4% by 2100, but by up to 13.5% if the temperature rises by +4.3°C. For each degree of warming, a reduction of 2.46% is expected. Thus, fishing and climate combined could reduce sequestration by 56% by 2100 compared to 1950.

A new natural solution for the climate?

The study quantifies for the first time the benefits of restoring fish and macroinvertebrate populations: up to 0.4 billion tons of_CO2 sequestered per year, a potential comparable to that of mangroves. Over several decades, this would represent 240 billion tons of_CO2, equivalent to six years of human emissions. SNCs linked to the restoration of commercial species populations therefore appear to be an interesting avenue to explore, but their contribution to meeting climate targets will remain minimal if these measures are not considered complementary to a drastic and immediate reduction in greenhouse gas emissions. The researchers also highlight numerous uncertainties surrounding this new field of research. "For example, the effect of restoring commercial species on their prey, which are also involved in sequestration, remains unknown. While it is difficult to conclude that this is a new CCS, our results nevertheless illustrate the importance of managing the ocean more sustainably to avoid the destruction of a carbon sink whose protection could bring benefits for biodiversity and the climate," they conclude.   

Keywords: Climate change, Research, Science, Company