After months in the nursery at the university’s Pacific Aquaculture and Coastal Resources Center, the young oysters are hardy enough to survive the heavily sedimented waters of Mā‘alaea Harbor.
Oysters raised at the Pacific Aquaculture and Coastal Resources Center (PACRC) at the University of Hawai‘i at Hilo are being used to improve ocean water quality in Mā‘alaea Harbor on Maui. The project, launched Feb. 1 with a short ceremony at the harbor, is headed by Maui Nui Marine Resource Council.
“Oysters are nature’s most efficient water filters; they eat by pumping large volumes of water through their bodies and in the process, they capture sediment and pollutants from the water column,” says Amy Hodges, programs manager at Maui Nui Marine Resource Council. “Estimates are that a single oyster can filter up to 50 gallons of ocean water in a day depending on conditions.”
“Our goal is to use the oyster’s natural filter feeding abilities to make Mā‘alaea Bay cleaner and healthier for fishing, swimming, paddling and surfing,” notes Hodges.
Maui Nui Marine Resource Council is conducting this project in partnership with O‘ahu Waterkeepers, a neighbor island nonprofit who installed oysters at Pearl Harbor, Kāne‘ohe Bay Marine Corps Base, and Ala Wai Harbor in 2019 for the purpose of improving ocean water quality and clarity. (See links to stories posted below.)
Hodges explains that the oysters installed in Mā‘alaea are Pacific oysters (Crassostrea gigas) which are found throughout the main Hawaiian Islands. “The broodstock for the oysters that we are installing in Mā‘alaea came from Hawai‘i, and were then raised in ideal conditions at the Pacific Aquaculture and Coastal Resources Center at the University of Hawai‘i at Hilo,” she says.
After months in the nursery at the university’s aquaculture center, the young oysters are now believed to be large and hardy enough to survive the heavily sedimented waters of Mā‘alaea Harbor. The oysters will live in cages below the water surface and away from boat traffic. They were raised triploids, meaning they are sterile and likely unable to reproduce.
“Oysters are used around the world to help improve water clarity and quality,” says Rhiannon Chandler-‘Īao, executive director of Waterkeepers Hawaiian Islands. “Cleaner water allows for sunlight penetration, which is important for corals and other animals.”
The first oyster project of this type in Hawai‘i was launched to restore native oysters to actively improve water quality and clarity at locations around the island of O‘ahu. Over 10,000 oysters produced at the UH Hilo aquaculture center have been out-planted at Joint Base Pearl Harbor-Hickam, the Marine Corps Base at Kane‘ohe Bay, the Hawai‘i Yacht Club and the Waikiki Yacht Club in the Ala Wai Harbor, and most recently at Honolulu Community College’s Marine Education and Training Center at Sand Island.