How Science is Saving Hong Kong's Oyster Industry

Oysters have been cultivated in Deep Bay in northwest Hong Kong for more than 700 years. But the future of this traditional industry is uncertain as sales of the saltwater delicacy have been steadily falling due to fears of contamination.

The main threat to the oysters (Crassostrea hongkongensis) comes from pollution and climate change that has led to a major decline in the industry over the last 50 years. As a result, only about 60 families now farm the shellfish from the fishing village of Lau Fau Shan, and this number is predicted to drop further as oyster farmers retire or change professions.

However, Dr Vengatesen Thiyagarajan (Dr Rajan), Associate Professor in the School of Biological Sciences and The Swire Institute of Marine Science of The University of Hong Kong, believes the industry can be saved if the oyster farmers adapt new technologies.

"The oyster is named after Hong Kong, so we should take care of this business and we should provide a solution for the sustainable development of this industry for new generations of farmers," said Dr Rajan. "And we slowly need to change the psychology of our local population towards the consumption of these oysters."

Dr Rajan is working with the Hong Kong government's Agriculture, Fisheries and Conservation Department and the Deep Bay Oyster Cultivation Association on adapting a depuration system where harvested oysters will sit in ultraviolet-sterilised seawater for a few days to remove bacteria.

He hopes to bypass climate change issues, which results in fluctuating water temperatures in Deep Bay, by constant monitoring of the conditions at each raft and by cultivating young oysters in a controlled environment in a purpose-built hatchery.

Crassostrea hongkongensis also suffer from heavy metal contamination but Dr Rajan said this can be monitored with only those oysters that are safe to consume, below an accepted threshold, taken to market.

Hong Kong is not the only location in difficulty as oyster numbers are in decline around the world as a result of rising sea temperatures and increased pollution.

"I'm looking for ways to tackle the climate change and to produce healthy oysters in a sustainable way," Dr Rajan said. "So basically I want to identify the strains that can tolerate climate change, that can produce healthy seeds and healthy products in our local waters."

Dr Rajan believes that adapting these new methods can make oyster farming in Hong Kong a sustainable aquaculture industry.