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April 2004 Vol. 30, No. 4   RSS Feed for Undercurrent Issues
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Divers and Home Aquariums

if you want to conserve reefs, why do you have that aquarium?

from the April, 2004 issue of Undercurrent   Subscribe Now

"We who dive along the Kona Coast have seen a drastic and definite reduction in our tropical fish populations over the past few years, due in part, at least, to the tropical fish collectors' increasing numbers." So says Dick Dresie, aka "Dick the Diver," who conducts shore dives at Hawaii's most popular sites. His concerns are being echoed by divers and conservationists worldwide.

Rene Umberger of Octopus Reef says "the entire southern Maui coastline has been impacted by fish collecting (and run off), including Ulua Beach, Makena Landing, and 5 Graves."

In Vanuatu in the South Pacific, reefs are over-exploited for the lucrative trade. A spokesman for tourism companies, Peter Whitelaw, told ABC Net News: "There are particular reefs that they've targeted and a lot of them are the very reefs to which we take snorkelers and divers." At Hat Island, dive operators told the Manchester Guardian, 38,000 fish were taken within one month last year.

Near Bali's Barat National Park, the Wildlife Conservation Society has seen a considerable decline in aquarium species. Prompted by cyanide fishing at Helen Reef in Palau and Komodo National Park in Indonesia, The Nature Conservancy is working to prevent the long-term effects of this practice. Collectors squirt cyanide into crevices where fish hide. The poison stuns the fish, making them easier to catch. But large numbers of the weakened fish die in transit, so far more fish are collected than necessary, to allow for a "fatality margin." The poisons destroy reef ecosystems by killing nontarget animals including coral and invertebrates. In the Philippines, 70 percent of ornamental reef fish are caught with cyanide.

Most coral reefs are located in developing countries. While fish collecting is a source of income for the people, the aquarium trade has been heavily criticized for damaging techniques occasionally used to collect the animals, overharvesting some species, and the high mortality from inadequate handling and transport of sensitive living organisms. Improper collection and shipping practices can introduce alien species, result in overharvesting, and threaten the extinction of target species.

The roster of nations exporting marine ornamentals reads like a diver's wish list. Besides those already mentioned, divers in Florida, Australia, the Caribbean, Tonga, the Solomon Islands, Fiji, the Maldives, the Marshall Islands, Samoa, Micronesia, the Dominican Republic, Mexico, Sulawesi, and Kenya all collect marine organisms for export. Many work the same reefs that we travel thousands of miles to visit.

As we reported last July, tropical fish sales have soared since the release of the Oscar-winning animated feature "Finding Nemo." Blithely ignoring the movie's message, hobbyists are rushing to set up saltwater aquariums stocked with beautiful fish, corals, and invertebrates.

Americans Collect Half the Reef Fish Taken

More than 20 million tropical fish are sold for aquariums each year, 98 percent captured in the wild. The trade brings in $330 million a year, according to a new report from the U.N. Environment Program entitled From Ocean to Aquarium. As many as two million people worldwide keep marine aquariums, 600,000 households in the United States alone. Americans buy 50 percent of the marine fish captured and 80 percent of the stony corals.

Of the 4,000 species of fish that live on coral reefs, 1,471 species are traded worldwide. Damselfish make up almost half, with angelfish, surgeonfish, wrasses, gobies, and butterfly fish accounting for another 25 to 30 percent. The most traded species are blue-green damselfish and clown anemonefish (heeere's Nemo!).

Many ornamental fish quickly belly up in captivity. Graeme Faulkner, owner of Perth Aquarium Centre in Australia, points out that tropical marine organisms require lots of special handling. "You need to spend [hundreds of dollars] to set them up in the right environment," he says. That includes a sizable tank, special lighting, proper food (live prey for some species), live substrate with plenty of hiding places, and filtration.

Naive aquarists often buy fish that aren't suited to home tanks. The bluestreak cleaner wrasse and the spectacular mandarin fish, for example, are commonly traded, though they do not acclimate well to aquarium conditions. Foureye butterflyfish, harlequin filefish, and Hawaiian cleaner wrasse are also popular despite their restrictive dietary requirements. As a result of high mortality rates, more fish are collected than necessary to meet market demand -- further depleting wild populations.

At the other end of the spectrum, nurse sharks are popular with aquarists, though they are highly predatory, often eating other organisms in the same tank. If they live long enough, they'll eventually outgrow home aquariums. (Try flushing one of those down the toilet!)

More than 20 million tropical fish are sold for
aquariums each year, and 98 percent are
captured in the wild on reefs. Americans buy
50 percent of the marine fish captured and
80 percent of the stony corals.

How Collectors Destroy Reefs

Those who collect marine organisms in the wild tend to be small-scale fishermen who work alone or in small groups, either selfemployed or working for a wholesaler/ exporter. In Sri Lanka and the Maldives, collectors use hand nets. In Australia, the Pacific region, and Florida, fishers often use much larger barrier, drop, or fence nets. Branching corals, which provide shelter to chromis and other small critters, are often snapped off to extract fish hiding among them.

Although poisons like cyanide are illegal in most countries, the U.N. report notes that "the high premium paid (often large bribes), the ease with which a great number of fish can be caught in a short time period, the often poor law enforcement capacities, and high levels of corruption have allowed the use of poison to spread rapidly throughout the Asia-Pacific region and have made the eradication of this illegal and highly destructive fishing technique nearly impossible."

For most species, juveniles are preferentially targeted due to their distinctive coloration, ease of maintenance, and size ratio with respect to tank size. However, should juveniles consistently be heavily harvested, "adult populations will suffer as only a limited number of young will grow to reach adult size and replenish the adult stock." Some species are endemic to certain waters (such as the scribbled angelfish of Australia and Papua New Guinea). Others are naturally rare, occurring only in restricted locations, or naturally lower numbers. Other species may be abundant at different sites, but their distribution is limited to specific habitats. Ironically, increased rarity creates higher prices.

Banggai cardinalfish are sought for their appearance and easy adaptation to aquariums. But they are restricted to the reef and seagrass habitat of the Banggai Islands off the east coast of central Sulawesi, Indonesia. They have the lowest fecundity rate of their species and a low dispersal rate of their eggs, and they've been proposed for listing as "critically endangered." Seahorses form faithful long-term pair bonds, mating exclusively with one partner. If a collector separates a pair, the reproductive cycle ends. Males of many coral reef fish species, such as mandarin fish, are preferred due to their distinctive coloration. But, concludes the report, "selectively harvesting males of particular populations on a regular basis may lead to reproductive failure and ultimately population collapse due to heavily biased sex ratios in remaining schools."

Sometimes unwanted aquarium fish are released into local waters, taking hold as alien species. Examples include Moorish idols, sailfin tangs, bursa triggerfish, and racoon butterflyfish. Six lionfish were accidentally released in Biscayne Bay, Florida, from a home aquarium during Hurricane Andrew in 1992. Divers are now seeing lionfish as far north as the Carolinas.

Trade in Live Coral, Sponges, and Anemones

Besides fish, 140 species of stony coral and 60 different soft corals are traded worldwide, perhaps as many as 12 million pieces a year. Some, like carnation coral, lack the ability to create food through photosynthesis and must filter particles and nutrients in the water column; in aquariums, they usually die within a few weeks. According to the UNEP report, "significant reductions in population densities of corals due to collection of colonies for the aquarium trade could have implications on their reproductive success and thus longterm reef stability and health."

More than 500 species of invertebrates -- sponges, molluscs, shrimps, and anemones -- are also traded as marine ornamentals. The annual trade estimate is as high as 10 million animals. Collectors harvesting corals and other immobile invertebrates often use hookahs and carry hammers, iron crowbars, chisels, or screwdrivers to remove colonies. The most popular invertebrates mainly feed on algae, parasites, or dead tissue (e.g., cleaner shrimp) and dead animals (e.g., hermit crabs). These species are particularly important in keeping other aquarium fish healthy. However, removing them from their natural habitats reduces diversity on harvested reefs, once their cleaning services are no longer available.

Fiji is the world's primary supplier of live rock (covered with decorative coralline algae and other tiny invertebrates). Besides being pretty, these organisms consume waste and produce oxygen, filtering aquarium water. Each year, 800 tons are harvested from the edges of Fiji's reefs or within shallow lagoons -- about 95 percent destined for the U.S. Much harvested live rock, subsequently considered unsuitable for export, is discarded and thrown back into the sea.

Large-scale removal of live rock, the result of hundreds of years of accretion, can undermine the structure of coral reefs. Some harvesting areas in Fiji have been converted into rubble and may never recover. With help from the World Wide Fund for Nature, some Fijian villagers have declared their traditional fishing grounds a taboo area, banning extractions.

Many countries prohibit certain capture methods (such as cyanide in Indonesia). Some set size limits for individual species and require permits or licenses. Florida prohibits collection from certain sites (marine reserves or other restricted areas like those in Hawaii). However, rules and regulations vary from one country or political jurisdiction to the next, as does enforcement.

Should a Conservation- Minded Diver Have a Home Aquarium?

All this raises the question: Should scuba divers who have seen first hand just how important it is to conserve reefs own aquariums at all? Sure, they look cool, but we get to see these critters in their natural habitats -- which is even cooler. So why encourage someone to remove them?

About the only proper way a diver can own a saltwater aquarium is to stock it with species raised just for that. Eric Borneman, author of Aquarium Corals: Selection, Husbandry, and Natural History, says, "be aware of what wild collected species are common, and which are not, and always purchase sustainably collected, maricultured, or aquacultured stock." Fish that are aquacultured (tank raised) or maricultured (cultivated in their natural environment) can be purchased from most reputable dealers and websites. However, merely two percent of the marine aquarium fish traded are cultured -- the rest come from the wild. Only a few cultured species are available, primarily clownfish, dottybacks, and gobies. As Borneman says, "they may cost you a bit more, but these specimens will be selected and bred to thrive in captivity, so you can expect them to enjoy longer and less stressful lives than wild transplants."

Large numbers of the weakened fish die in
transit, so far more fish are collected than
necessary, to allow for a "fatality margin."

If, however, you still can justify keeping captured fish in your home, then look for stores certified by The Marine Aquarium Council (MAC), which develops standards for quality wild-caught products and sustainable practices. Collectors, wholesalers, exporters, importers, and retailers are evaluated and certified for compliance with these standards. Certified retailers displaying MAC labels on their windows and tanks offer MAC-certified marine ornamentals from certified suppliers. Only a handful of suppliers and dealers are currently certified (see§ion=3).

You can download the report From Ocean to Aquarium by the U.N. Environment Program at

- Larry Clinton

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