Hong Kong - When the impotence drug Viagra was launched in 1998, few people could have foreseen the seismic impact its introduction would have on the underwater existence of a peculiar-looking and sexually ambiguous member of the Hippocampus genus.

Seahorses have for 600 years been used in traditional Chinese medicine as a cure for impotence, served up in rice wine, mixed up raw with herbs or dished up in soup as a source of potency and virility.

Rather than diminish its appeal, the arrival of Viagra appears to have spurred a huge increase in demand for impotence remedies using seahorses as a cheaper alternative to the western wonder drug that was making headlines around the world.

Twenty-five million seahorses a year are now being traded around the world - 64 percent more than in the mid-1990s - and environmentalists are increasingly concerned that the booming trade in seahorses is putting the creatures at risk.

Just this month, seahorses were added to a global watch-list of endangered species, obliging 161 countries and territories around the world to monitor the trade in seahorses and prohibit the trade in any specimen under 10cm in length.

There is an irony in the use of seahorses as a means of boosting virility. Modern research has established that, if anything, the male of the species is more in touch with its feminine side than anything else in the animal kingdom.

Seahorses are unique in being the only species where the male gets pregnant. The female injects eggs into the male who has a pouch where the eggs are fertilized and carried for up to four weeks until they are ready to be born.

Seahorses can also lay claim to being the most romantic creature on the planet, performing a dainty daily underwater dance with partners and generally staying faithful for life. Experts have found this to be the case even if they are placed in a tank full of single, available seahorses of the opposite sex.

Increasing numbers of seahorses are now finding themselves premature widows and widowers, however, as the demand for seahorses for use in traditional Chinese medicine continues to expand.

By 2001, the last year for which comprehensive figures are available, global consumption had reached 70 metric tons, equivalent to 25-million seahorses compared to just 45 metric tons seven years earlier, and there is every sign that this trend is continuing.

Samuel Lee Kwok-hung is the Hong Kong-based representative of the Marine Medicinals Conservation Programme, a joint initiative by Traffic East Asia and the United States-based research group Project Seahorse.

He says rising demand for traditional medicine alternative to impotence drugs like Viagra had pushed up seahorse consumption. Most seahorses are imported through Hong Kong and Singapore.

"The majority of the demand is from China," he said, explaining that seahorses are used to treat asthma and other conditions as well as impotence and sexual dysfunction.

The surging demand for seahorses from the mid-1990s coincided with the arrival of Viagra and was a "major driving force" in the increased demand for seahorses, said Lee, but the opening up of China also played a large role.

"With China becoming more and more open for foreign investment and for exporting products out of China the trade in traditional Chinese medicine is on the whole increasing," Lee said.

Spiralling demand is meanwhile driving the dragnet further and further afield with increasing amounts of dried seahorse being imported from outside the two main markets of Thailand, the Philippines and India.

Last year, South American countries including Peru and Mexico accounted for three per cent of imports to Hong Kong while another 2,1 percent came from African countries such as Mozambique and Gambia.

Demand now far outstrips supply, according to Project Seahorse. Hong Kong traders say the potential sales for seahorses are "limitless", raising concerns among conservationists that the trade will continue to boom even as the global numbers of seahorses decline.

A number of factors make seahorses more vulnerable to depopulation: The fact that males carry the eggs makes their survival more important than with other species; small brood sizes and low levels of mobility make it slower for numbers to grow; and their "one partner for life" tendencies make widowed seahorses reluctant to find a new partner.

They are also highly prone to the dangers of their environment. Up to 50 seahorses are born at a time, adults in miniature and independent at birth. Few reach maturity however because of its array of predators including crabs, tuna, skates and rays. Many adults are killed by storms, tearing them from the vegetation they cling to and killing them either from exhaustion or being tossed ashore.

Last week's move may not only be a lifeline for the 34 species of seahorses: Conservationists also believe it may make a crucial difference in their efforts to preserve them by letting them know the scale of the threat facing the world's seahorse population.

Seahorses were added to the list of protected species under the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES), meaning all 166 member nations will be required to regulate the cross-border trade in seahorses.

"Because of this, we will know the trade better in one or two years," said Lee, who added that the most important aspect of the Cites listing of seahorses was the prohibition in the trade of seahorses less than 10cm in length. Seahorses range in length from 2,5 to 25cm.

Project Seahorse is not calling for an end to the use of seahorses in traditional Chinese medicine.

In developing countries it is often the only affordable form of treatment and its rise in popularity along with the Viagra phenomenon in the west is understandable. What's more, the medicines they are used in appear to be effective and boast six centuries of satisfied customers.

"We can't say don't buy seahorses," said Lee. "Rather, we are asking people to use them in a sustainable way. If we collect more information we will know more about the impact the trade has on the world population."

The Cites listing would have an important impact on source countries. "In the past exports may not have been properly reported or declared to customs," said Lee. "Now they need to abide by the Cites requirements or the penalty will be huge."

"As for consumers, we want people to be aware of the concern. Our message is for people to use seahorses sustainably and not to buy specimens that are less than 10cm in length."

(More information about the work of Project Seahorse is available on www.projectseahorse.org) - Sapa-DPA