Our ocean has absorbed more than 90% of the heat from human-caused global warming—it’s not surprising that this greatly impacts ocean animals and the communities that depend on them. The question is how they will be affected. This is especially pressing for something as economically, ecologically and culturally important as our ocean’s fisheries. 

How fish will respond to ocean warming is a complicated question, with an even more complicated answer. Let’s dive in. 

How is climate change affecting our ocean? 

Let’s start with the obvious: Our ocean is getting warmer. The top layer of our ocean (up to about 2,300 feet) has warmed about 1.5 degrees Fahrenheit (0.83 degrees Celsius) since the beginning of the 20^th century. Although that might seem like a small amount to us, it can be a big deal for ocean animals. In addition to this warming trend, extreme ocean warming events, called marine heatwaves, have become more frequent and more intense.  

Warmer waters aren’t the only problem, though. As our ocean absorbs carbon, it becomes more acidic, which is especially bad news for shell-building organisms like oysters. Plus, warmer waters hold less oxygen; globally, ocean oxygen has declined 2% since 1960 with some areas showing decreases of up to 50%. 

What does climate change mean for fish? 

All animals—including fish—have a range of temperatures and conditions where they feel most comfortable (we can relate, right?) Although some animals can tolerate temperature increases just fine, others can experience stress or even death.  

When animals experience stressful conditions, they have four choices: adapt, move, die or stick around and stay stressed out. We’re already seeing these strategies play out in fish. Researchers have found that winter skate, for example, can adapt their body size to better suit warmer waters. Summer flounder, a popular seafood species, moved its range about 70 miles further north than it was in the 1970s. And a 2013 collapse of the stock of Atlantic northern shrimp in the Gulf of Maine was tied to an marine heatwave in 2012. 

Some effects of climate change aren’t as easy to spot as shifting ranges or fish stock collapses, however. Stress from a changing ocean can decrease fish stock productivity, which is the number of fish that are born and survive to adulthood in a population. Reduced productivity can cause ripple effects in the ecosystem and lower the number of fish that can be caught. 

Thinking about how fish respond to temperature isn’t enough to predict their response to climate change, though. Even if a fish species can adapt to warmer waters, other climate change impacts—like heatwaves, algal blooms and hurricanes—can wreak havoc on the habitats that they depend on, not to mention their interactions with food and predators. If fish don’t have food to eat or a place to live, there’s a problem. 

How does this affect communities? 

Fish and fisheries have massive economic and cultural significance in communities around the world. Stock collapses and declines in stock productivity mean there are fewer fish to go around, which is especially problematic given that billions of people around the world rely on seafood as a key source of protein. 

For many communities around the world, fishing is more than just a way to provide food: It’s a way of life. This is particularly the case for some Indigenous communities and cultures who are already at an increased risk of experiencing negative effects of climate change. Changing conditions in Northwest Alaska, for example, are making it harder for subsistence fishers to access their fishing spots, to catch fish and even follow traditional fish-drying practices. 

It’s also bad news for the 10 to 12% of people around the world who depend on fisheries and aquaculture to support their livelihoods, including fishers and those who process, transport, sell and cook seafood. Plus, it’s disappointing news for the many people who go fishing for recreational reasons.

Shifting ranges make it hard for fishers to access their catch, too. Thanks to climate change, marine animals are expected to shift their range about 18-32 miles per decade, making it difficult for fishers to access the species they’ve traditionally caught/targeted. This problem is especially acute for subsistence and small-scale fishers that may not be able to travel as far or make other changes to the way they fish.

What do we do? 

First and foremost, we need to continue to reduce greenhouse gas emissions. Fortunately, ocean-based climate solutions are available and effective.  But even if we successfully reduce emissions, we know there is warming ahead that poses serious challenges to fish and fisheries. That means that climate adaptation in fisheries is a path we must take. 

To make our fisheries climate-ready and maintain resilient fish populations, we need more data about how fish are responding in current conditions to help us predict how they will respond in the future. That means strategically expanding fisheries surveys, incorporating Traditional Ecological Knowledge into science and management, and supporting research on impacts. At the same time, we can’t wait to have perfect knowledge to act. There are actions fishery managers can take now to support fish stocks to make them more resilient to climate change and proactive ways to make sure fishers and fishing communities can adapt. 

Although there is much we still need to do, there a lot of this work already underway. To see for yourself, check out NOAA Fisheries’ recently launched its Climate Vulnerability Assessment Tool, which summarizes the vulnerability of fish and other marine animals across the United States. You can also see how fishery ranges have changed over time with NOAA’s Distribution Mapping and Analysis Portal. For over 25 years, Ocean Conservancy has worked to find practical solutions to the challenging problems facing our fisheries. We can all play a role in helping fish by advocating for climate-ready fishery management and calling for ocean-powered climate solutions. Learn more about the ways we’re tackling some of the problems facing our ocean’s fisheries.