Artificial reefs 'planted' to benefit Hong Kong dolphins

Last month, the government's Department of Agriculture, Fisheries and Conservation began "planting" artificial reefs in the hope that they will eventually attract enough fish to satisy the dolphins' diet.

Twenty-four aging river barges, 42 container units and thousands of hollow concrete blocks are being sunk in Sha Chau and Lung Kwu Chau Marine Park at a cost of US$650,000. Artificial reefs attract colonies of marine organisms, which in turn provide a source of food for fish.

"Dolphins frequent that area and we expect them to use the site a lot more now that the artificial reefs have been put down," said Keith Wilson, senior fisheries officer for the department.

Artificial reefs are not new, but this is believed to be the first time they have been deployed for the benefit of dolphins. Kindhearted sentiment wasn't the only motivation behind the effort. The reef project was required as mitigation for a temporary aviation fuel depot built in the dolphins' primary habitat.

Hong Kong's dolphins belong to the Indo-Pacific humpbacked species, which is widely distributed from South Africa to Australia to the Chinese coast of the Yangtze River. But what has made these particular dolphins, as well as populations in the South China Sea and Southeast Asia, such a favorite of admirers is their coloring.

Born nearly black, the dolphins gradually become white or pink as they reach adulthood. Their striking pink body color appears almost rouge-like against the dark blue water as they leap and frolic in group formation.

One theory is that the pinkness is caused by blood vessels dilating from exertion or overheating, much like flushing in humans.

Scientists and environmental groups would like to believe that artificial reefs offer compensation for the many manmade ills to which the dolphins have been subjected, but a there are concerns about the effectiveness of the program.

"I'm not really excited about it, but there's no harm in trying," said Thomas Jefferson, co-director of Hong Kong's nonprofit Ocean Park Conservation Foundation established for the conservation and long-term management of marine mammals in Southeast Asia.

Jefferson believes more urgent issues such as improving the quality of Hong Kong's water, should have a higher priority. Every day, for instance, some 190,000 cubic meters of largely untreated sewage are dumped into the dolphins' western harbor environment. DDT and heavy metals, including mercury, have also been found in dolphin tissue samples.

Others question whether the artificial reefs will enhance fish stocks. "If not designed for a particular species, there's no scientific evidence to support that they do," declared Yvonne Sadovy, associate professor in the department of ecology and biodiversity at the University of Hong Kong.

Wilson begs to differ. Based on a large-cale artificial reef program under way in Hong Kong, a 40 percent increase in fish stocks over the next 15 years is indicated, he said.

For Hong Kong's long-suffering dolphins, it's a matter of wait-and-see.