Fuel consumption and air emissions in one of the world's largest commercial fisheries.

The little information available on fuel consumption and emissions by high seas tuna fisheries indicates that the global tuna fleet may have consumed about 2.5 Mt of fuel in 2009, resulting in the production of about 9 Mt of CO2-equivalent greenhouse gases (GHGs), i.e., about 4.5-5% of the global fishing fleet emissions. We developed a model of annual fuel consumption for the large-scale purse seiners operating in the western Indian Ocean as a function of fishing effort, strategy, and vessel characteristics based on an original and unique data set of more than 4300 bunkering operations that spanned the period 2013-2019. We used the model to estimate the total fuel consumption and associated GHG and SO2 emissions of the Indian Ocean purse seine fishery between 1981 and 2019. Our results showed that the energetic performance of this fishery was characterized by strong interannual variability over the last four decades. This resulted from a combination of variations in tuna abundance but also changes in catchability and fishing strategy. In recent years, the increased targeting of schools associated with fish aggregating devices in response to market incentives combined with the IOTC management measure implemented to rebuild the stock of yellowfin tuna has strongly modified the productivity and spatio-temporal patterns of purse seine fishing. This had effects on fuel consumption and air pollutant emissions. Over the period 2015 to 2019, the purse seine fishery, including its support vessel component, annually consumed about 160,000 t of fuel and emitted 590,000 t of CO2-eq GHG. Furthermore, our results showed that air pollutant emissions can be significantly reduced when limits in fuel composition are imposed. In 2015, SO2 air pollution exceeded 1500 t, but successive implementation of sulphur limits in the Indian Ocean purse seine fishery in 2016 and 2018 have almost eliminated this pollution. Our findings highlight the need for a routine monitoring of fuel consumption with standardized methods to better assess the determinants of fuel consumption in fisheries and the air pollutants they emit in the atmosphere.

Publisher Correction: Productive instability of coral reef fisheries after climate-driven regime shifts.

In the version of this Article originally published, a technical error meant two proof corrections were not actioned. In the sentence that started "Fishery changes were underpinned…", a citation to ref. 9 was missing, and that to ref. 22 was misplaced. The sentence should have read: "Fishery changes were underpinned by species' differential responses to the post-bleaching benthic trajectories, suggesting that projections for reef fisheries that are based on habitat-driven loss of fish biomass (for example ref. 9) have overlooked the potential for increased productivity of low trophic levels22, particularly browsing herbivores on regime-shifted reefs." These errors have now been corrected in the Article.

Productive instability of coral reef fisheries after climate-driven regime shifts.

Tropical coastal communities are highly reliant on coral reefs, which provide nutrition and employment for millions of people. Climate-driven coral bleaching events are fundamentally changing coral reef ecosystems and are predicted to reduce productivity of coral reef fish and fisheries, with significant implications for food security and livelihoods. Yet evidence of long-term bleaching impacts on coral reef fishery productivity is lacking. Here, we analyse over 20 years of fish abundance, catch and habitat data to assess long-term impacts of climate-driven coral mass mortality and regime shifts on nearshore artisanal coral reef fisheries in the Seychelles. Contrary to expectations, total catch and mean catch rates were maintained or increased after coral bleaching, consistent with increasing abundance of herbivorous target species in underwater surveys, particularly on macroalgal-dominated reefs. Catch instability increased as habitats followed divergent post-disturbance trajectories and the distribution of target species became more spatially variable, potentially impacting fisher incomes and local market supply chains. Although coral bleaching increased fishery dependence on herbivore species, our results show that climate-impacted reefs can still provide livelihoods and fish protein for coastal communities.