The global aquaculture industry has tripled in size since the year 2000, with producers raising a mind-boggling diversity of species, from seaweeds and clams to carp, salmon and cuttlefish. Many of these creatures are undomesticated and lead complex and highly social lives in the wild.

The rapid growth in aquaculture means that billions of individual aquatic animals are now being farmed without basic information that could help ensure even minimal welfare standards. Our newly published study shows that these welfare risks are not uniform: Aquaculture is likely to have severe effects on welfare for some species, but negligible impacts on others.

Whenever humans manage animals on a large scale, welfare becomes a concern. As experts on aquatic animals and their welfare, we believe that taking proactive measures to shape the aquaculture industry’s growth will be critical for its long-term success.

Complex aquatic lives

In a wide-ranging review of the existing science, we identified seven risk factors in fish and other sea creatures that would be challenging or impractical to accommodate in captivity. They include 1) migratory behavior, 2) solitary social structures, 3) long life spans, 4) carnivorous feeding habits, 5) cannibalism, 6) living at depths of 165 feet (50 meters) or more, and 7) elaborate courtship or involved parental care.

We researched these characteristics for each of the more than 400 species currently farmed in aquaculture. Our analysis found that many species of fishes, reptiles and amphibians are likely to suffer in aquaculture because they won’t be able to engage in their natural behaviors in farmed conditions. The same is true for crustaceans such as lobsters and for cephalopods such as cuttlefish.

In contrast, aquatic plants and other invertebrates such as oysters would experience fewer differences between their life in the wild versus in a tank, pond or other aquaculture production system.

We also found that species most at risk are among the most expensive on the market but contribute the least to global production. By shifting toward species whose behaviors and life habits are more compatible with aquaculture, the industry could minimize animal welfare risk while also keeping prices down and production quantities high. In other words, protecting aquatic animal welfare is compatible with producing affordable, nutritious food.

Animal welfare in the water

Research shows that many aquatic animals are intelligent, emotional, curious, highly social and have strong preferences. Like land animals, they can suffer if their needs aren’t met.

Consider, for example, the bumphead parrotfish (Bolbometopon muricatum), which is currently farmed in aquaculture. Bumpheads live up to 40 years and travel several kilometers each day in large foraging troops, searching for live coral. On full moons, they come together in the hundreds to spawn and engage in ritual head-bumping contests between the males, like an aquatic version of bison.

It would be very difficult and expensive to accommodate this species’ long life span, large range, complex foraging behavior and dynamic social relationships in the highly restrictive and monotonous environments of aquaculture.

We also found examples of invertebrate animals with similarly elaborate ways of life. One example is the red swamp crayfish (Procambarus clarkii), a comparatively small crustacean that builds elaborate tunnel and chamber systems underground. Females care attentively for their tiny offspring, fanning, cleaning and feeding juveniles for up to four months after they hatch.

In contrast, plant species farmed in aquaculture, such as seaweeds and water spinach (Ipomoea aquatica), are nutritious, protein-rich foods that can be raised without posing direct animal welfare concerns.

In 2021 alone, 56 species were farmed for the first time. By identifying species that may naturally adapt better to life in captivity, aquaculture producers and policymakers can steer their industry toward a more humane future.

This approach is already finding support in the U.S., where Washington and California have banned octopus farming. The states acted partly in response to research showing that octopuses are intelligent, curious, social animals that can solve problems and recognize individual people – qualities that are incompatible with being raised en masse for food.

More research is needed to understand the lives and behaviors of other sea creatures that are currently farmed or targeted for production in the future. Most of these species remain understudied and mysterious, which makes it hard to make informed decisions about whether they are suitable for farming.

Better data could contribute to aquaculture policy, while also boosting public appreciation for the diversity and intricacy of life on a planet that is 70% aquatic.

Becca Franks receives funding from TinyBeam Foundation and Open Philanthropy.

Chiawen Chiang does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.