Impotency drugs such as Viagra have proven such a success with Chinese men that they are turning away from traditional therapies, say researchers.

The findings by Bill von Hippel, a psychologist at the University of NSW, and his brother Frank, a biologist at the University of Alaska, emerge from a study of 250 men, aged 50 to 76, at a Chinese medicine clinic in Hong Kong.

The brothers believe this means less demand for seal penises, which are usually ground into a potion. Or green turtles - which are turned into a soup - and their eggs, which are eaten separately. Or seahorses and pipe fish, whose entire bodies are ground down.

Reindeer can also provide a boost when the velvet that covers its horns is stripped away. And don't forget the multi-purpose tiger, whose bones and penis are prized.

The research received funding from Viagra's developer, Pfizer. The findings, published in Environment Conservation, are consistent with previous research by the von Hippels showing that prices for seal genitalia fell from $100 to about $20 after Viagra was introduced in 1998.

"They have no use whatsoever for anything but the erectile dysfunction trade," Dr Bill von Hippel said. "We believe that over time it will be the same story with other animals."

"Erectile dysfunction was the one case where they were more likely to be currently using western medicine than Chinese medicine and nobody had switched from Viagra back to traditional therapies."

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