Heatwaves in the ocean could cause six percent more fish catches to be lost, threatening millions of people's jobs. Credit: Cassiano psomas at Unsplash
A new UBC study shows that extreme heat will destroy hundreds of thousands of tonnes worth of fish in the country's waters this century. This is in addition to projected declines in fish stocks due to long-term climate changes.
Researchers at the UBC Institute of the Oceans and Fisheries used a complex model that included extreme ocean temperatures in Exclusive Economic Zones (where the majority global fish catches occur) into climate-related projections.
They projected that there would be a 6 percent decrease in potential catches annually if no action is taken to reduce greenhouse gas emissions. Additionally, 77 percent of the exploited species will see a drop in biomass (or the number of fish per area) due to very hot years. These declines are higher than those predicted by long-term, decadal-scale climate changes.
These are the numbers
Sockeye salmon catches in Pacific Canada are expected to drop by 26 percent during high temperatures events between 2000-2050. This would result in a loss of 260-520 tonnes of fish annually. If a temperature extreme happens in the 2050s and causes a decrease in annual catch, it would result in a total loss of more than 50% or 530-1060 tonnes of fish.
The extreme heat event in 2000-2050 is expected to cause a decrease of 34 percent in Peruvian anchoveta catch, which would mean a drop of more than 900,000. tonnes annually. A temperature extreme could cost Peruvian anchoveta fishermen more than 1.5million tonnes of their potential catch due to climate change.
A high temperature extreme event will cause a 25% drop in Peruvian anchoveta fisheries' annual revenues, or approximately US$600 million.
A high temperature extreme in Indonesia's waters between 2000-2050 could result in nearly three million job losses in the fisheries sector.
These extreme events and climate change are expected to cause some stocks to rise, but not enough for the loss mitigation.
Researchers projected that during extreme ocean temperatures and the predicted temperature rises each decade, fisheries' revenues and employment would both fall by three percent and two percent respectively, a possible loss of millions.
Professor and director of UBC’s Institute for the Oceans and Fisheries, Dr. William Cheung said that "these extreme annual temperatures will cause an additional shock to an already overloaded system." "We have seen that countries with weak fisheries due to long-term changes like ocean warming or deoxygenation will feel the effects of extreme temperature increases. This will likely increase the fisheries' ability to adapt." This is similar to COVID-19, which adds an additional burden to the healthcare system.
Professor at the University of Bern's climate and environmental physics division, Dr. Thomas Frlicher says extreme temperature events will be more frequent in the future. "Today's extreme heatwaves in the ocean and their devastating effects on fisheries are indicators of the future, as they are creating environmental conditions that will not be created by long-term global warming for many decades."
Researchers found that some areas are more vulnerable than others. These include the Indo-Pacific region, which includes waters around South and Southeast Asia and the Pacific Islands, as well as the Eastern Tropical Pacific region, which runs along the Pacific Coast of the Americas. There will also be some countries in West Africa.
Bangladesh is home to one-third of its workforce in fisheries-related industries. An extreme marine heat event will reduce two percentabout onemillion fisheries jobs. This is on top of the six million jobs that will be lost due to climate change by 2050.
Similar conditions are expected for Ecuador where extreme heat events will adversely affect an additional 10%, or approximately US$100million, of its fisheries revenues. This is on top of the 25% reduction that was anticipated by the middle of the 21st century.
Cheung stated that "this study really highlights how important it is to find ways to deal marine temperature extremes quickly." These temperature extremes can be difficult to predict, especially in hot spots that have limited scientific capacity to make accurate predictions about their fisheries. When planning for adaptations to long term climate change, we must be aware of this unpredictability.
Cheung stated that it is crucial to manage fisheries effectively. Possible adaptations include increasing catch quotas for years where fish stocks are affected by extreme temperatures, or closing down fisheries to allow stocks to rebuild. Cheung stated that we need mechanisms to address it.
Co-author Dr. Colette Wabbitz, an IOF research associate, and the Stanford Center for Ocean Solutions lead scientist, stated that it is important to collaborate with communities affected by these adaptation options. The stakeholder list is diverse and includes not only the industry but also small-scale fisheries, Indigenous communities and other stakeholders. They should be included in discussions about climate change and the impacts of marine heatwaves, as well as the design of and implementation of solutions.
Additional information: William W. L. Cheung and colleagues, Marine high temperatures extremes increase the impacts of climate changes on fisheries and fisheries. Science Advances (2021). Information from Science Advances William W. L. Cheung and colleagues, Marine high temperatures extremes increase the effects of climate change on fisheries and fisheries (2021). DOI: 10.1126/sciadv.abh0895
