Oceans heat up. So does concern for protecting fish.

It’s not just Earth’s air that’s been hot lately. The oceans are warming, too. 

Last year was their warmest to date, in records going back to the 1800s. Further records have been smashed this year, with global sea surface temperatures reaching unprecedented levels every month so far since May. And in June, Antarctic sea ice levels reached their lowest since satellite observations began – with a drop of some 2.6 million square kilometers (1 million square miles).

The warming trend has big implications for ocean life, and therefore also for the “blue foods” that make up an important part of human diets. In Alaska, a sharp decline in Bering Sea snow crabs – which experts saw as linked to a prolonged marine heat wave – caused the cancellation of this year’s harvest. Coral, a foundation for major ocean ecosystems worldwide, faces widely noted risks from bleaching. Scientists say warming also contributes to ocean-life challenges such as oxygen depletion, acidification, and fish being pushed to migrate from their usual habitat. 

Researchers are sounding warnings but are also pointing toward possible solutions – some of which appear to be gaining momentum over the past year. Measures to protect marine ecosystems are rising. Efforts to raise awareness are having an effect. More broadly, the world’s efforts to curb overall emissions of heat-trapping gases in the atmosphere are seen as key to stabilizing temperatures in oceans as well as on land.

The outlook, to many experts, remains sobering. But in the quest to safeguard ocean life, a common thread may be the importance of collaboration, whether the efforts are local or global in scope.

“The oceans don’t have borders - maybe political boundaries, but there really aren’t any that say this fish belongs to this country, etc.,” says Alexandra Dempsey, CEO of the Khaled bin Sultan Living Oceans Foundation, a Washington-based nonprofit dedicated to preserving and restoring the world’s oceans. “So being collaborative in terms of a network of scientists and educators that don’t just represent interests of one country is really important.”

A collective challenge

In fact, no one nation or group can hope to solve the challenge for marine life alone.

“Transboundary collaboration is actually, I think, really important,” says Ling Cao, a professor at the College of Ocean and Earth Sciences at Xiamen University in China, and one of the lead authors of a recent paper on the pressures facing blue foods. “We know that the water ecosystems are collective – like our oceans, they are all connected.”

In their study, Dr. Cao and her colleagues found that more than 90% of blue food production faces “substantial risks” from environmental change, taking into account myriad factors from pollution to the way climate change is prompting fish to migrate and boosting acidification as more carbon dioxide enters the oceans. 

That assessment doesn’t even consider the pressures of harvesting by humans. Although the worldwide catch has generally continued to rise, overfishing currently affects an estimated one-third of global fish stocks (up threefold since 1970). And the warning comes as other research also points to rising marine threats. Perhaps the most notable danger is a possible stalling of Atlantic conveyor currents including the Gulf Stream, with fallout for everything from fish to rainfall patterns in the Amazon. 

Protection efforts rising

The rising challenges are stirring a response, even if the steps are modest so far. 

Some point to a recent United Nations High Seas Treaty, adopted in June, as a beacon of hope – although it does await ratification to go into effect, and some experts caution that in terms of fishing, the high seas account for just 4% of the global catch. There is also the “30 by 30” goal to protect 30% of the planet’s oceans and land by 2030, agreed to during the 2022 U.N. biodiversity conference, which would represent a crucial milestone.

“Countries’ exclusive economic zones are of far more importance,” says Enric Sala, a National Geographic explorer in residence, and founder of the Pristine Seas project. “This is where the urgency really is, and this is where the greatest opportunities lie because individual countries can [designate protected areas].”

In waters extending up to 200 miles from their coastlines, nations can unilaterally declare marine protected areas (MPAs), where fishing can be restricted or prohibited. As countries help fish populations regenerate, this can be good news for both the fish and the fishers.

“Having MPAs is a fundamental part of an improved fisheries management regime,” says Callum Roberts, professor of marine conservation at Exeter University, and co-author of a study on their benefits in the Firth of Clyde in Scotland. “Traditionally, they’ve fished everywhere, but if you’ve got a backbone of areas where the fish are protected, it’s much easier to bounce back from a collapse.”

This doesn’t mean that establishing protected areas is a one-step panacea for marine biodiversity. But the zones can play an important role alongside things like fishery management policies and locking up carbon by nurturing seaweed.

In the Caribbean and elsewhere, researchers have been finding that protecting specific zones has spillover benefits for fish populations elsewhere, among other gains for the environment.

While these zones are often implemented by single countries, some of the largest have seen international collaboration. A Pacific “mega” protected area was created, for example, in 2021 when Colombia, Costa Rica, Ecuador, and Panama agreed to expand their protected territorial waters and join them up, creating a contiguous fishing-free corridor covering more than 200,000 square miles of ocean.

Perhaps the best example is the world’s largest – in Antarctica’s Ross Sea region. The protected area is three times the size of California. Its 2016 creation was supported by all key parties, including Russia, China, the United States, and the European Union. 

The other part of the equation is ensuring that where fishing is carried out, it happens in a sustainable manner.

Often this isn’t the case. As temperatures have pushed mackerel northward in the North Atlantic, for example, fishing boats have followed. The mackerel catch has been 41% above levels recommended by scientists since 2010.  

Equally, however, there are places where the picture is much rosier. In U.S. federal waters, 93% of fish stocks are not subject to overfishing, and in New Zealand, the figure is close to 87%.

“So there are some amazing signals, thanks to countries taking management seriously,” says Manuel Barange, director of the fisheries and aquaculture division at the Food and Agriculture Organization of the U.N. “We must recognize success as well as the problems, because if not, it will be impossible to convince those that are falling short that they can succeed.”

Casting a wider net for allies

Experts say that aiding at-risk marine life will require support from others beyond policymakers – such as researchers, local people on front lines, and new generations caring for habitats.

“I know that for coastal ecosystems, they are greatly overstressed, overfished, but the younger generation in the coastal communities where we work really is taking notice and caring about changing past practices when it comes to fishing and developing,” says Ms. Dempsey of the Living Oceans Foundation. “They’ve been able to see ... that we’re beginning to run out of resources, and they’re starting to take pride in looking after their nations’ resources.”

Adaptation costs money, and the world isn’t currently responding quickly enough to keep pace with the changes, says Kathy Mills, who heads the U.N. Ocean Decade’s fisheries strategies unit. Still, she remains optimistic.

“One of the things that gives me hope is human ingenuity,” says Dr. Mills, who is a senior research scientist at the Gulf of Maine Research Institute. “I interact with quite a few fishermen, and they have always been entrepreneurial in adapting to changes, and I think that spirit is an innate part of human culture.”