Sea cucumbers are benthic echinoderms that feed on algae, decaying organic matter and other meals they can salvage from the sea floor.
The Squaxin Island Tribe is looking into whether the marine animals’ voracious appetites can be put to use cleaning hatchery net pens.
The tribe is in the second year of a project to discover whether it can use sea cucumbers to cut down on staff time cleaning algae and other organic matter from the net pens that house young salmon.
The tribe manages day-to-day operations at the net pens between Squaxin and Harstine islands, which are operated jointly with the Washington Department of Fish and Wildlife. The net pens can hold up to 2.6 million coho salmon.
Rana Brown, a shellfish biologist with the Squaxin Island Tribe, said she and other staffers had noticed, while diving, sea cucumbers eating organic matter off rocks like vacuums.
“They appear to eat a lot and you can observe them cleaning off rock faces and substrate,” Brown said.
That observation—and plentiful numbers of sea cucumbers— led to adding 30 individuals to one net pen last year. At the end of the coho rearing season, the sea cucumbers were released.
With results of the first foray inconclusive, 175 sea cucumbers were added this year to more net pens. The tribe is analyzing data to determine if and how much the animals grew during the project time. This will give some indication of their grazing activity in the pens.
Amanda Hsu, GIS manager for the Squaxin Island Tribe, left, and Eric Sparkman, a shellfish biologist for the tribe, measure sea cucumbers at the tribe’s salmon net pens to study whether the invertebrate could help keep the nets clean. Photo and story: Trevor Pyle
