Industrial fisheries have reversed the carbon sequestration by tuna carcasses into emissions

Type Article
Date 2023-09
Language English
Author(s) Mouillot DavidORCID1, 2, Derminon SuzieORCID3, Mariani GaëlORCID1, Senina InnaORCID4, Fromentin Jean-MarcORCID6, Lehodey PatrickORCID5, Troussellier MarcORCID1
Affiliation(s) 1 : MARBEC, Univ Montpellier, CNRS, IFREMER, IRD Montpellier , France
2 : Institut Universitaire de France, IUF Paris, France
3 : Université Paris‐Saclay, CNRS AgroParisTech, Ecologie Systématique et Evolution Gif‐sur‐Yvette ,France
4 : Satellite Oceanography Division CLS Toulouse, France
5 : Mercator Ocean international Toulouse, France
6 : MARBEC, Univ Montpellier, CNRS, IFREMER, IRD Montpellier , France
Source Global Change Biology (1354-1013) (Wiley), 2023-09 , Vol. 29 , N. 17 , P. 5062-5074
DOI 10.1111/gcb.16823
Keyword(s) blue carbon, climate change, modeling, Natural Climate Solutions, population dynamics

To limit climate warming to 2°C above preindustrial levels, most economic sectors will need a rapid transformation toward a net zero emission of CO2. Tuna fisheries is a key food production sector that burns fossil fuel to operate but also reduces the deadfall of large-bodied fish so the capacity of this natural carbon pump to deep sea. Yet, the carbon balance of tuna populations, so the net difference between CO2 emission due to industrial exploitation and CO2 sequestration by fish deadfall after natural mortality, is still unknown. Here, by considering the dynamics of two main contrasting tuna species (Katsuwonus pelamis and Thunnus obesus) across the Pacific since the 1980s, we show that most tuna populations became CO2 sources instead of remaining natural sinks. Without considering the supply chain, the main factors associated with this shift are exploitation rate, transshipment intensity, fuel consumption, and climate change. Our study urges for a better global ocean stewardship, by curbing subsidies and limiting transshipment in remote international waters, to quickly rebuild most pelagic fish stocks above their target management reference points and reactivate a neglected carbon pump toward the deep sea as an additional Nature Climate Solution in our portfolio. Even if this potential carbon sequestration by surface unit may appear low compared to that of coastal ecosystems or tropical forests, the ocean covers a vast area and the sinking biomass of dead vertebrates can sequester carbon for around 1000 years in the deep sea. We also highlight the multiple co-benefits and trade-offs from engaging the industrial fisheries sector with carbon neutrality.

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Mouillot David, Derminon Suzie, Mariani Gaël, Senina Inna, Fromentin Jean-Marc, Lehodey Patrick, Troussellier Marc (2023). Industrial fisheries have reversed the carbon sequestration by tuna carcasses into emissions. Global Change Biology, 29(17), 5062-5074. Publisher's official version : , Open Access version :