Coral Safe

Joan Holt would like to see a day when the saltwater fish tanks at your local pet store have a big label slapped on them that says “Coral Safe.”

Joan Holt would like to see a day, in the not-too-distant future, in which the saltwater fish tanks at your local pet store have a big label slapped on them that says “Coral Safe.”

“It’s the kind of thing that could transform the industry in the way that the idea of ‘organic’ has changed the way people grow and buy fruits and vegetables,” says Holt, professor and associate chair of marine science at The University of Texas at Austin. “We need to make sure that people who want to stock their saltwater tanks sustainably will know how to do it.”

Holt, associate director of the Fisheries and Mariculture Lab at The University of Texas at Austin Marine Science Institutein Port Aransas, is part of a community of marine biologists around the globe developing the means to efficiently breed saltwater aquarium fish, seahorses, plankton and invertebrates. They hope to preserve the biologically rich ecosystems of the world’s coral reefs in places such as Southeast Asia and the Persian Gulf, where these creatures are collected for aquariums.

These scientists believe their efforts could help shift much of the $1 billion marine ornamental industry toward entrepreneurs who are working sustainably to raise fish for the aquarium trade.

Holt recently co-authored a paper in the Journal of the World Aquaculture Society, “Advances in Breeding and Rearing Marine Ornamentals,” that surveys the state of the science in breeding the kinds of creatures that fill the spectacular saltwater tanks often seen at restaurants or in the lobbies of corporate offices.

The paper is a complement to the broad-ranging work that Holt has done over the past 10 years to promote captive breeding of ornamentals. As a researcher she’s been a pioneer in developing food sources and tank designs that enable fragile larvae to survive to adulthood. As a member of the scientific advisory board of the Association of Zoos and Aquariums, she has worked to promote collaboration between scientists, aquariums, and commercial fish breeders. She’s also consulted with the Texas State Aquarium in Corpus Christi on how to raise seahorses in captivity, and has been a vocal critic of the extraordinarily wasteful methods currently used to bring sea creatures from the oceans to the tanks.

“One popular method is to use a cyanide solution,” says Holt. “It’s squirted into the holes and crevices of the reef and it anesthetizes the fish. They float to the surface. Then the collectors can just scoop them up, and the ones that wake up are shipped out.”

This method, says Holt, has a number of unfortunate effects. It bleaches the coral. It kills or harms other species that make the coral their home, particularly those that can’t swim away from the cyanide. It can deplete or distort the native populations of the species. And it contributes to 80 percent of traded animals dying before ever reaching a tank.

“There’s been a lot of time and money spent on trying to change the culture of how these species are caught,” says Craig Watson, who’s worked with Holt in his role as director of the Tropical Aquaculture Laboratory at the University of Florida. “But it’s very difficult to effect change in some of the source countries where a lot of these fish are coming from. If we took some of the money that has been spent trying to make that change, and steered it toward domestic aquaculture, as an alternative source for these fish, we might be able to do a lot quickly.”

The Art and Science of Breeding Ornamentals

Unlike the freshwater ornamental market, which relies mostly on fish raised in captivity, the saltwater ornamental market is 99.9 percent wild caught. Holt says this is largely because there’s less accumulated knowledge on breeding saltwater fish in captivity. Saltwater species also tend to spawn smaller, less robust larvae and fry, which are harder to rear to maturity, and to rely on various foods, such as plankton, that are not readily available in mass quantities for breeders.

Yet all these difficulties, says Holt, are surmountable.

She and her colleagues in Port Aransas, for example, have successfully bred in captivity seven species of fish and shrimp they’ve caught from the Gulf of Mexico and the Caribbean, including species that other biologists had tried but failed to rear before.

They succeeded, says Holt, by paying close attention to the natural conditions in which these species thrived, and by taking an experimental attitude toward figuring out what works.

The peppermint shrimp is one of the seven ornamental species that Joan Holt has learned how to breed successfully in captivity. Photo by Paul J. Thompson. Creative Commons license.
“My philosophy for all of this work is to go see what these animals are doing in nature,” says Holt, who’s been funded in this work by organizations such as the World Wildlife Fund, the Texas Sea Grant College Program, and the Hugh and Angela McAllister Foundation.

“We did one study in which one of my technicians went out to the coral reefs and trapped the larvae of similar species to those we were trying to breed. Then we looked at what was in their gut,” she says. “It turned out that the zooplankton in there were much smaller than what everyone had been trying to feed them. At the first stage of feeding they need very small food because they have really tiny mouths.”

Holt and her colleagues also engineered a sophisticated tank system that kept the food and larvae concentrated in one area, so that the larvae could access it, while constantly circulating fresh water through that area, to simulate the purity of the tropical waters in which the larvae are born in nature.

St. Leger is the driving force behind Rising Tide Conservation, which was created by the SeaWorld & Busch Gardens Conservation Fund to promote captive breeding. Rising Tide is awarding grants to scientists like Watson to advance the science, while SeaWorld and other big aquariums are working to integrate information about the coral reef ecosystems, and the damage being done to them by the ornamental trade, into their exhibits.

“A big part of this process is education,” says St. Leger. “By encouraging people to connect to marine species, and giving them the information about how these species are impacted by damage to the coral reefs, we can prepare them to be more informed consumers.”

Growing a Movement

Holt and her colleagues envision a “Coral Safe” movement. The science, the economics and the social awareness would move forward together. The eventual result would be a sea change in how saltwater aquariums are populated and how saltwater tank enthusiasts think of themselves and their passion.

“Right now there’s a culture of wanting to have only one of the species,” says Holt, “which is understandable, but people should know that their rare species were probably collected at great cost to the environment. As for the money, I think that’s less of an obstacle. These saltwater tanks are already much more expensive than freshwater tanks, and people are willing to put tons of money into them. They put in fancy lights, elaborate filtration systems. Some of these fish cost $50 or $60, even $120. A few bucks more probably won’t make much of a difference.”

Holt sees signs of progress. Scientists are beginning to organize. The Association of Zoos and Aquariums has encouraged its members to make their saltwater exhibits more sustainable. Watson and his Tropical Aquaculture Lab at the University of Florida have been systematizing what they’re learning about breeding ornamentals into protocols for commercial breeders, and the breeders, he says, are “chomping at the bit” to take that information and start selling the fish. And St. Leger, with the weight of SeaWorld and Busch Gardens behind her, is pushing to make the marine ornamental market look more like the freshwater ornamental market.

“In the freshwater fish market more than 95 percent of the fish are captively reared,” says St. Leger. “It’s the opposite in marine fish. We need to shift those numbers so that it’s more comparable, and I think we will.”

Holt’s own pilot efforts to cultivate a market for two species she’s bred — the peppermint shrimp and the fire shrimp — suggest consumers in Austin and Dallas are aware of some of the problems of wild-caught species and are willing to pay more for coral-safe alternatives.

As more tank-raised ornamentals percolate into the market, Holt believes people will see another advantage to buying sustainably. The fish will simply do better. They’ll live longer, be healthier and be easier to care for.

“Species that are bred in captivity should adapt much better to your tank than something that was just caught halfway across the world, in a different system,” says Holt. “Good retailers will want to sell these species, and consumers will benefit from buying them.”