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January / February 2004

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Aquaculture to Save the Coral Reefs

Aquaculture to Save the Coral Reefs
Two Ph.D. students are studying ways to more successfully reproduce tropical fish in captivity as a way to save natural habitat

About the Photo: Clown fish are among the tropical species successfully bred in captivity.

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You won't find tropical fish in the cold waters of the Gulf of Maine. In fact, Maine would be low on most people's list as a place to raise colorful clown fish, dottybacks and other coral reef dwellers. Two University of Maine graduate students are challenging that logic by delving into the details of tropical fish aquaculture. Their goal is to raise fish for the home aquarium industry, a market they estimate to have about $250 million in annual sales in the U.S.

In addition to pursuing their Ph.D. degrees in the School of Marine Sciences (SMS), Søren Hansen and Chad Callan have founded a company, Sea & Reef Aquaculture, LLC. With help from a $10,000 Maine Technology Institute seed grant, and from business development services at UMaine's Target Technology Incubator and the Maine Aquaculture Innovation Center, they intend to develop new methods and lower costs for raising saltwater aquarium fish.

"When I worked for a tropical fish importer, I got to see the dark side of the aquarium industry, as far as how many fish come in and how many die. The sheer volume of turnover (is enormous), and I didn't like it," says Callan, who grew up in New Jersey. "About 95 percent of the stock to supply those aquariums now comes from coral reefs. Less than 5 percent is raised in captivity. I wanted to get the industry more ecologically focused and supply this trade with cultured fish."

The methods used to capture tropical reef fish can harm the reef itself, Hansen explains. Since their quarry often hide inside the coral, divers sometimes use sodium cyanide solutions to stun the fish. In the process, they damage the reef environment and can kill the coral as well. In many cases, though the fish will survive this collection method, they usually succumb to the effects a short time later. Their lives in home aquariums tend to be short.

"It does seem a little crazy that we're growing tropical fish in Maine," Callan adds. "When people ask, we explain the environmental situation. There is a lot of aquaculture going on in Maine, and it's a natural transition to include this end as well."

Callan and Hansen credit David Townsend, biological oceanographer and SMS director, with facilitating their project. It all started in fall 2001 at UMaine when Hansen, a native of Denmark, was a teaching assistant for Townsend. Hansen was finishing his master's degree in fish physiology when he talked with Townsend about his interest in tropical fish aquaculture and his plans to start a business with Callan in Hawaii after graduation. At that time, Hansen was raising and selling clown fish, like the colorful star of the Disney movie Finding Nemo. However, he knew that extensive research and development were still necessary before a business venture could succeed.

Townsend's interest grew during a visit with Callan, who had received his marine biology master's degree from UMaine in 2000 and was working at a tropical fish aquaculture company in Hawaii. During a tour of the company's grounds, Townsend commented on the close proximity of the facility to the ocean. Since the fish being cultured at the facility were not native to Hawaii, he wondered about the ecological effects of potentially introducing exotic species to island waters.

Introduction of non-native species is a concern with aquaculture. "It occurred to me that if we were in Orono, Maine, that wouldn't be a problem. A tropical saltwater fish won't survive in the Penobscot River, let alone the Gulf of Maine," Townsend says.

Both Callan and Hansen applied to the UMaine marine biology Ph.D. program. They had conducted their master's research at the Aquaculture Research Center (ARC) in Orono and knew what it took to coax fish through their earliest life stages. Moreover, they knew that for most tropical reef fish, practically nothing is known about feeding preferences and reproduction. Although clown fish are raised successfully in captivity, techniques have not been developed for raising most of the more than 1,200 species of reef fish that are commercially traded.

In their research, Callan and Hansen are tackling those basic questions for clown fish, dottybacks, angelfish, wrasses and a few other selected species. Callan is focusing on the nutritional requirements of broodstock — what they need to eat to continue spawning and maximizing the quality of the eggs and larvae produced.

"These fish spawn in some cases every day, and at least once a week, year-round. They must spend a tremendous amount of energy producing those eggs, and they require a lot of nutrients to sustain that need on a continual basis," says Callan, who previously worked with nutritionist Linda Kling on techniques for raising cod.

"Commercial aquarium diets are geared toward just keeping the fish alive and may not be best suited for prolonged spawning. I'm going to produce a diet that will increase their spawning and larval survival potential. The big bottleneck is that larval stage and getting them past that first feeding hurdle," he adds.

That stage will be the focus of Hansen's work. He plans to use a high-speed video system to see exactly how fish larvae interact with their tiny zooplankton prey. Some zooplankton have anti-predator defenses that allow them to escape. Hansen will analyze the feeding process in split-second detail to determine how larval fish select their prey. "We'll get a better idea of what kind of prey we need to raise for these fish larvae and what prey concentration is optimal," he says.

Jacqueline Hunter, a technician at ARC, will help with raising the zooplankton prey for their studies. Hunter has extensive experience in raising rotifers and brine shrimp — live feed organisms that are commonly used for aquaculture research purposes.

Researchers elsewhere are working on similar questions, but much of that is being done in places where the water stays warm year-round.

"What we're trying to show is that, because these fish are so small and you can have large numbers in a small area, there's potential to have this type of business in a non-tropical location," says Hansen. You can have such an operation totally indoors so it doesn't affect coastal resources, Callan says. "It's a clean, indoor aquaculture setting. And potentially, it has a high value — a higher value per fish than any food fish species."

Simultaneously starting a business and pursuing a Ph.D. program are not for the fainthearted. "Neither one of us could do this alone," says Hansen. He and Callan are always on call in case their aquarium research system should malfunction. Day in, day out, they share a pager that is triggered by sensors monitoring water quality and other aspects of the fish-rearing system.

Nevertheless, they are committed to both the science and the business. "We're hoping to bring a lot more attention to marine ornamental aquaculture as a whole, and make people aware that tank-raised fish are becoming more available and are an environmentally sound alternative to buying fish collected from the reefs," Callan says.

by Nick Houtman
January-February, 2004

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