A professor at The University of Texas at Austin is hoping to see the day that the saltwater aquarium fish trade will adopt sustainable fish collecting methods that are “coral safe,” much like the food trade has adopted the organic food moniker that has changed the way some people purchase food. Dr. Joan Holt, professor and associate chair of marine science at The University of Texas at Austin is part of a movement of marine biologists worldwide who are trying to save the marine reefs and ecosystems of the world from the onslaught of fish gathering by way of cyanide use, among other methods. Cyanide fishing, which is widely practiced in ornamental fish rich countries such as the Philippines, is killing reefs and the animals that inhabit them in an effort to quench the world’s thirst for ornamental saltwater fish. Holt hopes to change that with captive breeding efforts, which is how today’s tropical fish are propagated for the freshwater aquarium trade. Holt, co-author of the paper, “Advances in Breeding and Rearing Marine Ornamentals,” and published in the Journal of the World Aquaculture Society, believes that captive breeding of marine ornamental fish is the only way to ensure the survival of the coral habitats in which these species live.
Holt’s paper details the state of the science of captive breeding of marine species, including details on spawning, plankton culturing, embryo development and larval rearing, as well as aquarium design. It also discusses the need to create a reliable system for tracing animals and distinguishing sustainably caught or cultured animals from wild caught animals.
It is known that the vast majority of marine ornamental fish are wild caught, largely due to lack of knowledge when it comes to breeding saltwater fish in captivity. This, Holt says, can change. Working with colleagues, Holt has successfully bred seven species of fish and shrimp in captivity that are native to the Gulf of Mexico and the Caribbean. They were successful because they were able to mimic the environments in which these animals lived by constructing custom aquariums that kept the larvae and zooplankton in one area of the tank while also ensuring that area of the tank was constantly circulated with fresh saltwater in an effort to simulate what happens in nature. The team also learned that certain larvae were eating very tiny zooplankton, so tiny that the team had to adjust what they were feeding the babies because their mouths were so small.
While seven species is minuscule in the grand scheme of the marine fish trade, it is a start, and Holt and her colleagues are hoping that the trend to captively breed popular species will catch on, for what she says is a better solution than wild caught specimens. The cultivation of freshwater fish for the aquarium trade in the United States started in the 1920s. By the 1970s, most of the more popular tropical fish were farm raised, and today, it is estimated that 95 percent comes from fish farms, said Craig A. Watson, Director, Tropical Aquaculture Laboratory at the University of Florida and a colleague of Holt. So how many years would it take for the saltwater fish market (which is a much larger market in terms of species), to reach a similar percentage of farm raised species as the freshwater fish trade? “A while,” Watson told FishChannel. “Not to be trite, but I really don’t know, as many of the best species still elude our best efforts, and the diversity in marine ornamentals is a significant challenge.”
Watson still remains hopeful that a change in how the industry acquires its marine fish takes root. “There’s been a lot of time and money spent on trying to change the culture of how these species are caught,” said Watson. “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,” Watson said in an article that appears on the University of Texas website.