Hawai'i's little red shrimp are a hot item
By Jan TenBruggencate
Advertiser Science Writer
Tiny red Hawaiian shrimp that live in anchialine ponds and underground crevices are turning into a popular aquarium species.
ãHawaiiâs Sea Creaturesä by John P. Cooper
The little shrimp may be the perfect aquarium animals. They are hardy, active and require very little care. They can live at a range of temperatures and salinity, from fresh water to ocean water.
Hawai'i's red pond shrimp, known in Hawaiian as 'opae 'ula, have become a popular addition to aquariums. However, heavy collecting as well as predatory fish could threaten the tiny creatures.
Big Island bonsai entrepreneur David Fukumoto, whose Kurtistown-based Fuku-Bonsai brought miniature trees to the masses, has launched a business selling aquariums with lava rock, a light and a bunch of the little shrimp, which are 'opae 'ula in Hawaiian and Halocaridina rubra to scientists. He calls the half-inch creatures "amazing Hawaiian micro-lobsters," and sells "mini-breeder" tanks on the Internet, starting at $89.95.
You'll also find them for sale in jars at swap meets and on Web sites. They have been sold as complete ecological systems in sealed glass spheres, and went into space in 2001 for observation on the International Space Station.
Fukumoto said the shrimp are sometimes collected and sold as live food for other aquarium fish, a practice he decries.
Stockly's Aquariums owner Bill Stockly of Kailua, Kona, said he sells both open and hermetically sealed aquariums with shrimp he raises in tanks. A softball-sized sphere sells for $19.95 and "microhabitats" start at $39.95.
"I started working with these animals 20 years ago," he said.
Both Fukumoto and Stockly said 'opae 'ula survive on microalgae and bacteria in the tanks if you don't feed them, although they may appear to get bigger and reproduce better if you do.
The shrimp are native to the Islands, and can be found in anchialine ponds — nearshore pools that don't connect to the ocean — on Moloka'i, Kaho'olawe, Maui, O'ahu and the Big Island. They are most common in the lava anchialine ponds of the west side of the Big Island.
Early Hawaiians collected the shrimp and used them as bait for the schooling mackerel, 'opelu.
Marine ecologist Richard Brock has studied the animals since the 1970s, and is somewhat concerned about the aggressive collecting. A healthy population of 'opae 'ula could sustain a lot of collecting, but the populations are threatened by predatory fish, he said.
"In the early 1970s, small numbers of pools had guppies, mosquito fish and tilapia. By 1985, a study indicated that 47 percent of ponds contained these fish, and now about 95 percent have them," Brock said. All of these fish eat the tiny shrimp, which are seldom found sharing the same pools today.
Brock said early Hawaiians would sometimes put fish into the anchialine pools to hold them for later consumption, and some of them, like aholehole (young Hawaiian flagtail), did eat the shrimp. But since the native fish did not complete their life cycles in the ponds, they did not develop permanent populations.
By dumping alien fish into the ponds, "we're closing off the habitat for these animals," he said.
Marine scientists have been able to find only one effective means of killing off the alien fish populations without harming the shrimp. It's an organic insecticide called rotenone, made from the sap of certain tropical plants. Brock said it is used at levels that kill fish but don't damage crustaceans, and which break down after a few hours in sunlight.
But rotenone is now prohibited from use in anchialine ponds in Hawai'i. Brock said he hopes the ban will be lifted so that some of the ponds can be restored to their native inhabitants.
Fukumoto said he buys his shrimp from a licensed collector, and is working on a captive propagation program so he can produce them without drawing on the wild animals. He said the shrimp are reproducing in captivity, but not yet in large enough numbers.
"We still have to collect until we develop our captive breeding program," he said.
He recommends feeding the animals spirulina powder, which he said is similar to the microalgae they eat in nature. Another benefit is that it floats and won't cloud the water, Fukumoto said. He provides buyers of his systems with a small vial of the feed, which he said will feed 25 animals for about one year.
Reach Jan TenBruggencate at jant@honoluluadvertiser.com or (808) 245-3074.
Correction: A small vial of Fuku-Bonsai's powdered spirulina, marketed as food for 'opae 'ula, will feed 25 animals for about one year. A previous version of this story suggested that the feed would last much longer.
