82 percent of native fish species in California are at risk of extinction in the next 100 years, largely because global warming will make water temperatures too warm for these fish, a University of California, Davis study revealed. The top 20 vulnerable native species identified include various types of salmon.
Peter Moyle, the lead author of the study, told The Tribune, “All the climate change projections suggest that water temperatures are going to get significantly warmer as time goes on…We’ll be making choices. Either we have these species around for the future, or we don’t.”
Moyle noted that some native species could avoid extinction if changes are made to store more cold water behind existing dams and released when water temperatures threaten each species’ survival. Further, Moyle believes that plans to restore access to large dams for some species may also help.
Jon Rosenfield, a conservation biologist at The Bay Institute, told The Tribune that the study’s results are not surprising. Another study has also concluded that global warming is affecting fish across the globe as a result of rising temperatures in waters.
A University of British Columbia study, released on May 15, found that catches from global fisheries are dominated by warm-water species as a result of fish migrating towards the North and South poles into deeper and cooler waters, in response to rising ocean temperatures. The University of British Columbia researchers used temperature preferences of fish and other marine species as a sort of “thermometer” to assess the effects of climate change on the world’s oceans between 1970 and 2006.
“One way for marine animals to respond to ocean warming is by moving to cooler regions,” said the University of British Columbia study’s lead author William Cheung. “As a result, places like New England on the northeast coast of the U.S. saw new species typically found in warmer waters, closer to the tropics…Meanwhile in the tropics, climate change meant fewer marine species and reduced catches, with serious implications for food security.”
All these studies highlight the urgency of addressing the decline in fish species and its effects on human life.
“We’ve been talking about climate change as if it’s something that’s going to happen in the distant future—our study shows that is has been affecting our fisheries and oceans for decades…these global changes have implications for everyone in every part of the planet,” warned Daniel Pauly, the principal investigator at the University of British Columbia’s Sea Around Us Project and the study’s co-author.
Jon Rosenfield drew a similar conclusion about the University of California, Davis study, calling it “an overwhelming and historic call to action” to address the effects of global warming on the ocean life. “We have the ability, and some would say the mandate, to change what needs to change to save these fish, and all the other resources that go along with them,” he told The Tribune.
Oceans at the front lines of global warming
Global warming’s effects on oceans do not end at rising ocean temperatures: oceans are increasingly becoming acidic because they are absorbing as much as 80 percent of additional heat generated by the greenhouse gas effect. The greenhouse gas effect is the process by which the atmosphere traps some of the Sun’s energy in order to warm the Earth enough to support life. Many scientists believe that human-driven greenhouse gas use is increasing this effect. These greenhouse gases include carbon dioxide emitted by burning fossil fuels and deforestation.
Overtime, carbon dioxide (CO2) and other greenhouse gas emissions have been absorbed by the oceans. While this has benefited the earth by slowing the global warming that these emissions would have caused had they remained in the air, they are changing the water chemistry—making it more acidic—and therefore, affecting the life cycles of many marine organisms.
Acidity inhibits shell growth in marine animals and is suspected to cause reproductive disorders in some fish. Assorted corals, clams, oysters, sea urchins, and some varieties of plankton are the most at risk of being affected by ocean acidifications. As a US federal agency called the Carbon Group of the National Oceanic and Atmospheric Agency notes, “When shelled organisms are at risk, the entire food web may also be at risk.”
Threat to food security
The rising ocean temperature’s effect on fish has serious implications for food security of regions, where fish is the staple food. In 2012, the United Nations Food and Agriculture Organization (FAO) estimated that the worldwide, the fishing industry yields 150 million metric tons of fish, worth $200 billion. For almost half of the earth’s billion inhabitants, fish comprises around 20 percent of protein in their diets. This number is significantly higher in poor and island regions where fish is the staple food.
According to a report by the Guardian, fish stocks in the tropics could fall by as much as 40 percent in the next half century as a result of global warming. This will threaten a vital food source for many in the developing world. Fish supplies could fall by over 20 percent by 2025 in the waters off Indonesia. Fisherman operating in China and Chile could also see large declines in fish stocks. Particularly, the dwindling fish stocks will severely affect many parts of Africa and South Asia, where people depend on fish and seafood for half of their animal protein.
“Basically you have lots of people living at the edge of the sea. They depend on fisheries, not in the way we do in northern countries. So income-wise and consumption-wise they are affected directly by the decline in catch,” Pauly told the Guardian.
Nurturing human and ecological resilience
According to a report by the National Geographic, local people, policy makers, and donors have a large influence on how rising ocean temperatures affect their lives and marine life. For example, coral reef—on which many in East Africa and the Indian Ocean depend—serves as a breeding ground for fish, and when well managed, can bounce back from the disturbance caused by rising ocean temperatures and remain productive. Similarly, local communities can build the adaptive capacity necessary to cope with the effects of global warming.
The National Geographic report notes that lessons on how to nurture human and ecological resilience can be found in coastal East Africa, where improvised communities are adapting to climate change and working to conserve their natural resources through innovations in governance and resource use. For instance, in Kenya, various communities have come together to identify effective forms of fishery management: through marine protected areas, fishing closures, and the banning of certain type of fishing gear (traps and fine-mesh fishing nets), local communities have found that they can conserve fish populations and manage how coral reefs cope with global warming.
However, the National Geographic report notes that the blending of adaptive capacity building and ecosystem management (regulation to rebuild depleting fishing stocks) is undermined by fishing activities of wealthier nations. Fishing contracts that allow wealthier nations to fish in Africa also allow these countries to process the fish in their own countries. This does not benefit the people of these poorer countries as they miss out on both jobs and resources.
While the coastal areas grapple with the dwindling fish stocks, both the University of California, Davis and the University of British Columbia studies highlight the urgency required in addressing the effect of global warming on the ocean temperatures and consequently, the fishing industry.