January 23, 2021

By Ramona du Houx

People naturally live and work around water—we’re drawn to it. Approximately 40 percent of the world’s population lives within 100 km (62 mi) of a coast.

Water is the most important natural resource on Earth as it is vital for life. Aquatic ecosystems, freshwater or marine, provide multiple benefits, such as provisioning of oxygen, food, drinking water, and genetic resources; regulation of atmospheric composition and climate; water purification; storm buffering; mitigation of floods/droughts; recreation areas; and other purposes. Humans depend on the health and well-functioning of aquatic ecosystems. Water is life.

But the world’s aquatic resources are currently under their greatest threat in human history from man made climate change. Freshwater ecosystems lost 83 percent of their biodiversity from 1970 to 2014. And coral reefs are disappearing at an alarming rate.

In January 2021, more than 111 aquatic societies representing 80,000 scientists working on all seven continents signed a statement, imploring the public and policy makers to take action on climate change. They warn that aquatic ecosystems are some of the most severely affected by climate change. They project that 90 percent of coral reefs will disappear by 2050 if we don’t take immediate action.

Last September, the same scientific societies sounded their first climate change alarm when they called for drastically curtailed global greenhouse gas emissions to avoid the worst impacts of man-made climate change to fish and aquatic ecosystems.

Unless urgent action is taken to reduce emissions, scientists predict catastrophic impacts to commercial, recreational, and subsistence fisheries and human health and global economies.

“Swift and resolute action by governments and by individuals to reduce emissions is essential to halt irreversible impacts to freshwater and marine ecosystems, fish, and fisheries from climate change. We must act now to safeguard our drinking water, food supplies, and human health and well-being.  These grim predictions for the world’s aquatic ecosystems are not just theoretical. They are affecting us now and failure to act will imperil future generations,” said American Fisheries Society President Scott Bonar.

Climate change is already altering marine and coastal ecosystems with significant implications for wild capture fisheries and marine economies.  Projected increases in ocean temperature are expected to reduce the maximum catch potential in most areas in the U.S.  Many harvested stocks will shift from one area to another, or even across international boundaries with implications for seafood supply, ports, and associated businesses. Loss of habitat from sea level rise will lead to declines in the vast majority of commercially and recreationally harvested marine finfish and shellfish that are dependent on estuaries and coastal systems for some stage of their life cycle. Increased carbon dioxide absorption is changing ocean chemistry, rendering some waters too acidic for marine organisms with calcium shells, such as oysters and clams, and threatening the base of the marine food web.

Freshwater fish are especially threatened by the impacts of climate change. Forty percent of all in North America are today imperiled as a result of pollution, habitat loss, water withdrawals, and invasive species. Climate change coupled with these existing stressors will lead to significant declines in freshwater fish, with devastating consequences for cultural, recreational, and economic value of freshwater systems.

“Climate change is warming rivers, lakes, and streams throughout America, reducing habitat availability for freshwater fish, particularly coldwater species.  Longer summers and warmer winters are reducing snowpack essential for maintaining blue ribbon trout fishing in the West.  Anglers and the recreational tourism dependent businesses that depend on them will see drastic declines in the number of fish and days on the water,” said AFS Executive Director Douglas J. Austen, Ph.D.

Lobster fishing in Belfast, Maine. The industry will suffer drastically if ocean acidification goes unchecked. Photo by Ramona du Houx

Across the globe, incomes, food security, and livelihoods of aquatic resource-dependent communities are already at risk. Climate change threatens food security by endangering fish, an essential source of protein for many across the globe.

“Fisheries provide a valuable protein depended on by billions of people, especially those in developing countries. Climate change is putting that key protein source at risk. The current trajectory of greenhouse gas emissions requires urgent attention to ensure the future of global fisheries,” said Bronwyn Gillanders, President of the World Council of Fisheries Societies.

“Coral reefs are threatened globally by rising temperatures, ocean acidification, surface runoff, and pollution. Unless dramatic action is taken to reduce greenhouse gases and local environmental impacts, coral reefs as we know them will probably not exist by the end of this century,” said Andréa Grottoli, President of the International Coral Reef Society.

According to the Food and Agriculture Organization of the United Nations, fish accounts for 17 percent of animal protein consumed globally, fishing and aquaculture directly employ almost 60 million people, and global trade in fish products has reached US$152 billion per year, with 54 percent originating in developing countries.

“Aquaculture, both freshwater and marine, employs over 21 million people and in 2018 accounted for 46 percent of global fish and seafood production and 52 percent of fish and seafood for human consumption. The impacts of human-caused climate change on production systems threaten this vital source of income and food security,” said Jimmy Avery, President of the World Aquaculture Society.

In addition to reductions in emissions, aggressive policies and programs are required to mitigate the effects of climate change to freshwater fish and to preserve habitat essential for resilience. If we are to avoid losing countless species that provide immeasurable benefits to society, we must also mitigate the impacts of climate change on fish and fisheries and plan for adaptation required to ensure the long-term health of our freshwater, coastal, and marine ecosystems and the many economies that depend upon them.  Intact, healthy habitats can help to provide resilience for fish and store carbon.

“When healthy, aquatic ecosystems are important allies that capture carbon and reduce climate warming, but when damaged, they may let go of the large amounts of carbon they hold. We need to protect our healthy aquatic ecosystems to maintain their crucial storage of carbon to help reverse the effects of climate change,” said Antonio Camacho, Chairperson of the European Federation for Freshwater Sciences.