‘Dark Maggot’ sea cucumbers to fill Hawaii’s fish ponds

Dubbed “dark maggots,” sea cucumbers have breathed new life into Hawaii‘s fish farms.

Kauaʻi Sea Farms, the Pacific American Foundation and NOAA (National Oceanic and Atmospheric Administration) are working to breed three species of sea cucumbers in hopes they will become high-value export products while bringing benefits to the local ecosystem.

Photo of a Namako sea cucumber. These sea creatures could revitalize Hawaii’s ancient fishponds.
Joseph Bennington-Castro/NOAA Fisheries

The project takes place in the Nomilo Fishpond on the southwest coast of Kauai, Hawaii. Located in an extinct volcanic crater, this particular pond is one of the oldest and most fertile in the entire state.

Hawaii has 488 of these so-called loko i’a, ancient aquaculture systems developed hundreds, if not thousands, of years ago to support sustainable fish farming. However, following the westernization of Hawaii in the early 20th century, many loko i’a fell into disrepair.

loko i'a fish pond in kauai hawaii
Stock image of Loko i’a fishing pond on Kauai, Hawaii. Many of these fish ponds are derelict.

Nomilo loko i’a had been abandoned since 1992 after Hurricane Iniki blocked its seawater channels and disrupted the flow of nutrients between the pond and the sea.

However, thanks to recent restoration efforts, Nomilo is now home to a healthy community of native species. But there is still a long way to go.

“We hope this project can help address some of the challenges Loko i’a faces, including water quality, viable food sources, and revenue to support recovery and management,” NOAA Aquaculture Specialist Tori Spence said in a statement.

Sea cucumbers are a group of marine animals found around the world. Their bodies are like squishy cucumbers with small, tubular feet and they can grow up to two meters long. They are considered a delicacy in many cultures, particularly in East and Southeast Asia.

Sea cucumber on the seabed
Stock image of a large sea cucumber on the seabed. Sea cucumbers can grow up to two meters long.
Whitcombe RD/Getty

According to Kaua’i Sea Farm, “Sea cucumbers are a key species for coastal ecosystems that are overexploited worldwide for high-value export markets.”

But growing them has other, non-monetary benefits as well. Sea cucumbers serve as underwater cleaning crews, scavenging up organic debris and other debris that has settled on the fishpond bottom.

Like the filter-feeding oysters and mussels used in other ponds, sea cucumbers can improve pond water quality. “[This] increases the number of fish that can thrive in the pond at one time,” said David Anderson, production manager at Kaua’i Sea Farm, in a statement.

The project focuses on raising three species of sea cucumbers native to Hawaii: surf snapper and white teak, which are widely used in Chinese cuisine and medicine, and namako, a species popular in Japanese cuisine.

Namako soup Japanese delicacy
Stock image of Sea Cucumber Soup. Namako sea cucumbers are a delicacy in Japanese cuisine.

The first phase of the project involves raising young animals in solar-powered hatcheries. Next, the team will conduct trials in different pond environments to study how the animals fare under different conditions.

In the final phase, Anderson and his team will work with Hawaii Sea Grant – part of a national network promoting coastal resource conservation – to conduct workshops and develop production manuals on how to raise and conserve different species of Hawaiian sea cucumbers.

“This project is investing in an opportunity to use restorative aquaculture to produce a potentially high-value export product,” Anderson said. “At the same time, fish ponds will be restored and fish production for the community will increase.”

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