Sustainable seafood guide: choosing fish with a low impact

Choosing sustainable seafood can feel really confusing. Fish is good for our health because it provides nutrients like protein, which we need to grow, heal and even fight off illness.¹ Plus, it contains omega-3 fats, which support brain and heart health.² But stories about overfishing, pollution, and harmful fish-farming practices can make it hard to know what to buy. They can even make us wonder whether we should be eating seafood at all.

Let’s break down the differences between wild-caught and farmed fish, what each method means for the planet, and how we can make seafood choices that support living oceans, thriving communities, and our own health. 

Wild-caught seafood

Wild fishing is catching fish that have lived and grown naturally in oceans, rivers or lakes. It  has been a vital source of protein in coastal communities for thousands of years. Even today, millions of people rely on wild seafood for food and work.³ 

When it’s managed sustainably, wild fish can be a healthy and low-carbon choice. It’s considered low-carbon because catching wild fish generally requires less land, freshwater, and energy than producing many types of meat. This means it creates fewer greenhouse gas emissions than meat, so it contributes less to climate change.⁴ 

Challenges: overfishing, bycatch, and habitat damage

Overfishing happens when fish are caught faster than they can reproduce. Right now, about 35.5% of wild fish populations are overfished.⁹ This happens for a few reasons:

• Subsidies encourage harmful fishing. Many big fishing fleets get government money to help pay for things like fuel.¹⁰ Without these subsidies, some of the most damaging fishing methods wouldn’t be profitable because they use a lot of fuel.
• Technology makes catching fish very efficient. Tools like sonar and satellite tracking help boats find fish faster than ever before.¹¹ This can quickly reduce fish numbers if there aren’t good rules to control fishing.
• Illegal fishing is common and hard to control. Up to 30% of seafood traded worldwide comes from illegal, unreported, or unregulated fishing.¹² This makes it very difficult to protect fish stocks. Illegal fishing is also linked to serious human rights abuses like modern slavery because these boats are hidden away from authorities. 
• Bycatch is a big problem. Around 10% of fish caught are bycatch, meaning caught by accident.¹³ This often includes dolphins, turtles, and young fish, which are usually thrown back dead.
• Some fishing methods harm habitats. Bottom trawling drags heavy nets along the seafloor, destroying fragile habitats like seagrass beds and coral reefs where young fish grow.¹⁴ This damages the ocean ecosystem.

Is the ocean running out of fish?

After hearing about all those sustainability challenges, it’s normal to feel a bit worried. You might even have heard dramatic newspaper claims like: “By 2050, the oceans will be empty.” The idea of waves rolling over nothing but silence and plastic bottles is terrifying. But thankfully, it isn’t realistic.

That’s right, the ocean will not run out of fish by 2050. Here’s what’s really happening:

• Around 65% of assessed fish stocks are fished at sustainable levels. This means they’re stable or increasing.¹⁵
• Roughly 35% are overfished. This is bad. It means populations are too low and need time and better management to recover.¹⁵
• At the same time, some stocks that were once in trouble are now rebuilding thanks to better rules, catch limits, and marine protected areas. This benefits the fish we eat and biodiversity more generally.

It’s important to know that a “fish stock collapse” doesn’t mean all the fish are gone. A wild fish stock is one particular type of fish measured in one particular place. If that stock collapses, it means the population has fallen so low that it’s not profitable or responsible to carry on trying to catch the remaining fish. When fishing pressure drops and habitats are protected, stocks can recover.¹⁶

What responsible wild fishing looks like

• Limits on how much fish can be caught. Rules based on scientific advice set limits to stop too many fish being taken. Monitoring is done through a combination of satellite tracking, electronic catch reporting, and sometimes physical inspections. 
• Fishing methods that avoid catching the wrong animals. Some ways of fishing, like using hooks and lines, are gentler and cause less damage than dragging big nets along the seafloor. New tools, like special escape routes and sounds that warn dolphins, help other sea animals avoid being caught by accident.¹⁸
• Using technology to catch fish responsibly. Tools like sonar and satellites help fishers find fish more easily. These technologies can also help track boats and stop illegal fishing, especially far out at sea.¹⁹ Technology itself isn’t bad, it depends on how we use it.

• Protected ocean areas. Some parts of the ocean are closed to fishing so fish can rest and grow. These safe zones help fish populations recover and spread, which can lead to bigger catches nearby.²⁰
• Knowing where fish comes from. New tracking systems, like QR codes, blockchain, and digital records, could help us see exactly where and how seafood was caught. This can make it harder for illegal fish to end up on the supermarket shelves. 

Read more about tracing your food here

Farmed fish

Fish farming, or aquaculture, is when fish are raised in controlled environments like sea cages, tanks, or ponds on land. Many people worry about fish farms, and for good reasons. Some farms cause pollution, have disease outbreaks, or rely heavily on wild-caught fish to make the feed that farmed fish eat. This means that even farmed fish can put pressure on wild fish populations.

However, the industry has made real progress in recent years. For example, farms have improved how they make fish feed so that they use fewer wild fish and more plant-based ingredients.²¹ This helps reduce the demand on wild fish and makes fish farming more sustainable. While challenges remain, many farms are adopting better practices to lower pollution and improve fish health.

Challenges: pollution, feed, and welfare

• Fish farms produce waste like fish poop and uneaten food, which add extra nutrients (mainly nitrogen and phosphorus) into the surrounding water. When these nutrients build up, they can cause too much algae to grow. This reduces water quality and lowers oxygen levels, making it harder for other plants and animals to live nearby. 
• Feed isn’t always sustainable, especially if a lot of wild fish are caught to feed farmed fish. 
• Fish welfare is an important concern. Farmed fish often live close together in crowded conditions, causing stress and making diseases spread. These diseases can pass between farmed and wild fish.

Responsible fish-farming practices

• Using more sustainable fish feed formulas. This means more plants, less wild fish!²¹
• Collecting and treating fish waste, so less pollution goes into rivers and seas. Some farms even turn fish waste into energy or fertiliser to grow food on land.²²
• Taking good care of fish. Keeping water clean and not crowding them helps prevent disease as well as being kinder.²³ 
• Certification programmes and clear labels like ASC help farms stick to some sustainability rules and let shoppers know their seafood is responsibly raised. (More on that later!)

How to make sustainable seafood choices 

Now that you know what sustainable seafood looks like, what can you do to make better choices? Here are some simple ways you can help support healthier oceans and better fish for everyone.

1. Look for trusted certifications

When you buy fish, check the packaging for official certification logos. You might notice little designs that look like certifications, but if you take a closer look these are sometimes just vague claims like “real fish” or “from the sea”. That doesn't really mean anything in terms of sustainability. 

If you want to make a real difference with your purchase, look for well-known labels such as:

• MSC (Marine Stewardship Council) for wild-caught fish
• ASC (Aquaculture Stewardship Council) for farmed fish
• Organic labels, which include extra rules on fish welfare and feed

These labels aren’t perfect, but they’re a great step in the right direction. 

2. Choose local or regional species

Climate change is shifting where fish live. Species that used to be common in southern Europe are now moving further north, while some cold-water fish are moving away.²⁷

This can lead to odd situations where countries export lots of one type of fish but then import loads of another fish from somewhere else. Often, this happens because we’re used to certain fish in our traditional dishes and menus.

Choosing local species helps reduce the environmental impact of long-distance transport and supports nearby fishers and communities. It might all start with a quick online search to find out what fish lives around where you live.

3. Try forage fish

Forage fish are small fish like mackerel, sardines, and anchovies that feed on plankton. They grow quickly, reproduce fast, and sit lower on the food chain. Plus, they tend to live close to the surface, so catching them uses less fuel compared to bigger, slower-growing fish that live in deeper water.²⁸

Interested in trying more seafood? Involve your family and friends by discovering the art of seacuterie.

4. Eat invasive species

In some regions, choosing invasive species helps protect the ecosystem. For example, in parts of the Mediterranean, the invasive lionfish is causing a lot of destruction. By choosing to cook with lionfish, chefs and consumers help reduce the pressure on local wildlife, all while discovering new and exciting flavours.²⁹

5. Be mindful of freshness and sourcing

Look for fresh, local, and seasonal fish to help reduce your environmental footprint. For example, visiting local fish markets or seafood counters that source directly from nearby fisheries lets you choose seafood caught closer to home. Restaurants or shops that highlight seasonal seafood on their menus or labels make it easier to pick fish that’s in season and caught responsibly.

Sustainable seafood is absolutely possible

Choosing sustainable seafood might feel tricky, but it doesn’t have to be overwhelming. Both wild-caught and farmed fish can be good choices when done right. Here’s a reminder of some easy wins the next time you’re in the supermarket:

• Look for certified labels like ASC or MSC. They aren’t perfect, but they’re the best we have for now.
• Choose smaller, fast-growing forage fish like sardines and mackerel instead of big predator fish.
• Eat seaweed and farmed shellfish as much as you like, as they don’t use many resources and can even do good for the planet.

And if you feel totally overwhelmed by all the choices, you can always ask someone at the fish counter for help. Or, if you’re not in the mood to chat, just get out your phone and have a quick look at an online guide.

Even if you just try one of these new habits, you’re on the right path. These choices all add up, meaning more fish in the water, better jobs for fishers, and food on our plates for years to come.