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
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
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
"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
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
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
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
for more stories from this issue of UMaine Today Magazine.