Sea cucumbers could clean up fish farms – and then be eaten by humans

Researchers are looking at introducing sea cucumbers to fish farms, where they could clean up fish waste and be bred for food

Marine net-pen fish farms aren’t popular with environmentalists for a number of reasons, one of the main ones being the amount of fish feces and uneaten food that they release into the surrounding ocean. In the UK, help for that problem may be coming in the form of the sea cucumber. Despite its name, the sea cucumber is an animal, that resembles a big slug and is about the same size as ... well, as a cucumber, or sometimes larger. Given that sea cukes subsist on organic matter that they scavenge from the sea floor, scientists at Newcastle University have proposed that they be introduced to fish farms where they could process waste. After eating all that fish poop, some of the cucumbers could then be served up as gourmet cuisine for humans.
Not only would this initiative theoretically be good for the environment, but it should also help sea cucumbers – perhaps not the ones that get eaten, but sea cucumbers in general. Because they are a rich source of glucosamine and chondroitin, the animals are currently harvested for use in traditional Chinese medicine and cuisine, to the point that worldwide populations of key species are declining. At fish farms, not only would they be used to minimize waste, but they would also be bred for the marketplace.
“We wanted to find a way to clean up waste produced by large-scale aquaculture so that farming activities in the sea have little or no impact on the ocean floor,” said Newcastle’s Dr. Matthew Slater. “By growing sea cucumbers on waste from fish farms we are not only farming a valuable food product and giving the wild sea cucumber populations a chance to recover, we are also developing solutions to fish farming impacts.”

After having studied them at Newcastle's Dove Marine Laboratory, the research team is now looking towards actually placing them at fish farms around the UK. The team is also leading an aquaculture project in Tanzania, where sea cucumbers are being bred in cages in a lagoon.
Fish farming has also been criticized for introducing antibiotics and anti-algal chemicals into the ocean, allowing escaped non-native fish to disturb the local ecological balance, creating higher levels of toxins in farmed fish flesh, and for putting strain on wild populations of fish caught to feed carnivorous domesticated fish such as salmon.
It’s hard to say if the cukes can help with all of that, but every little bit helps.