A True, Fish Story

Scientists at the Oceanic Institute made waves last November when they spawned red snappers in captivity. The procedure, they say, could generate pools of money in the future.

April, 2001

On an early morning fish feeding last November, scientists at the Oceanic Institute in Waimanalo were stunned as they examined one of four 10-ton tanks filled with captive red snappers. Inside a net basket were newly spawned fish eggs – up to 150,000 dots, each measuring approximately 0.8 millimeters in diameter. “There was a great deal of excitement,” recalls Robin J. Shields, research scientist in larval physiology for the institute. “We found that the eggs were fertile and viable, so we immediately took them to hatchery process right away to see how much mileage we could get from them.” Not only were the eggs 78 percent fertile, but the red snappers continued to spawn over the next six days.

That week symbolized a breakthrough in aquaculture technology, for the Hawaii institute and for researchers worldwide. It was the first time in more than 25 years that scientists achieved a natural, out-of-season spawn in captivity, a key aspect in completing the life cycle of red snappers. The process involves spawning the fish, growing their larvae to maturity and then spawning the second generation outside of their natural reproductive season (typically from June to September). It also was the first time red snappers were spawned naturally and out of season, that is, without hormones and without manual extraction.

The institute now faces the second hurdle: recreating that original environment to produce another natural spawn before the reproductive season begins this year. “We don’t know yet what the environmental or stocking conditions are,” Shields says. “This is our starting point, and now we can continue to develop and investigate what the animals need.” Red snappers naturally are aggressive and territorial fish that have been known to damage one another in captivity.“That’s (manual extraction) a relatively crude process, but an effective way of accumulating milk and eggs from captive fish,” Shields says. “They confine the animal, inject them, strip the eggs and mix them. That’s a lot of stress for any animal to go through.” To make the spawning as natural as possible, scientists at the institute simulated the species’ underwater habitat via proper lighting, food and ambient water temperature.

Although the November spawning occurred in Hawaii, the stock-enhancement project involves a consortium of researchers at the University of Southern Mississippi’s Institute of Marine Sciences and the Mote Marine Laboratory in Florida. The institute has received up to $350,000 in annual grants since 1996 from the National Marine Fisheries Service.

The federal grants are modest dollars compared to potential sales of red snapper, which can cost up to $7.89 per pound in the Gulf Coast region. An equivalent snapper in Hawaii can cost an average of $6.60 per pound. “It is a known and treasured fish,” says Joe Tabrah, the institute’s manager of technology transfer. “The demand is strong all up and down the Gulf Coast of the U.S. and the East Coast. In Hawaii, you’ll see that it’s an acceptable substitute for the other snappers we eat here.”

The institute hasn’t put its fish eggs in only one basket. Over the past decade, scientists there have completed the life cycle for other captive species, including Pacific white shrimp, moi (Pacific threadfin), mahi mahi, awa (Milkfish) and kahala (Greater amberjack), which is popular among Japanese. The institute annually provides about 250,000 juvenile moi to local farmers, who then grow and sell the fish commercially. Moi sales have skyrocketed over the past six years, generating up to $500,000 annually for moi farmers. “It got overfished in the 1970s, but we brought that fish back through stock enhancement,” says Brian White, communications manager for the institute. “It has allowed fishers to create their own farms, and suddenly, the restaurants and the markets have reliable sources for fish.”



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Cathy S. Cruz