From: Howard Breen <HBreen@island.net>
To: AQUA-L@killick.ifmt.nf.ca
PHOTOSTIMULATION TRICK ENHANCES ABALONE
Abalone farmers may find the following article from today's Bangkok Post of interest.
July 28, 1999
Abalone thrive on trick of the light
(by Peter Janssen)
An accidental breakthrough in commercial abalone raising has spawned a new breed of Thai farmers, said Tanate Poomtong, Thailand's leading abalone expert. He has spent the past 10 years researching the meaty sea mollusc at the Coastal Aquaculture Development Centre in Prachuap Khiri Khan.
Abalone is deemed a gastronomic delicacy in China, Hong Kong, Japan, South Korea and Taiwan. Posh Chinese restaurants in Thailand will pay 900 baht a kilogramme. In 1997, Thailand exported 75,000 kg of fresh abalone to Japan and South Korea, but so far exports have been limited to what fishermen could catch at sea.
Taking a tip from Japanese textbooks on clam farming, Mr Tanate decided to experiment with altering the abalones' natural routine by switching their night and day.
In the controlled environment of the hatchery, Mr Tanate and his team kept bright lights on all night and induced darkness in the daytime by shutting the indows and turning off the lights.
The abalone, being a nocturnal sea creature which usually engages in
reproductive activities around 1 a.m. had a very sexual reaction to the
trick. "They suffer stress and release hormones to promote gonad development, which makes them mature within three to five days. They will then release their sperm and eggs in an effort to reproduce quickly," Mr Tanate said.
The accelerated reproduction results in millions of fertilised eggs which are then removed and raised in separate tanks.
Mr Tanate said that he originally tried the trick to get the abalone to
spawn in the daytime and make it easier to collect their eggs.
"But the result was that they released their sperm and eggs every day. I
got this method by accident," he said. Given a 0.8% survival rate, a massive amount of eggs is needed to make abalone farming viable. Mr Tanate's technique also means that abalone can be induced to reproduce year-round, instead of seasonally. Another advantage for Thailand is its year-round warm climate, which make the local species-Haliotis asinina-grow to adult size of five to six centimetres
within nine months, compared with two to three years in colder climates.
In 1997 and 1998, working with a grant of two million baht from the Thai Research Institute, Mr Tanate improved his abalone hatchery and culturing techniques until the Fisheries Department felt confident enough to start training abalone farmers.
Thailand's first 47 abalone farmers were given their fingerlings from the Fisheries Department at a ceremony last May.
The cost of an earthen pond to raise the abalone is between 2,000 and 3,000 baht, but if the investor wants a hatchery as well the cost could be between 70,000 and 80,000 baht.
Mr Tanate said some of his intake had been shrimp farmers who feared a downturn in the industry following the European Union's partial removal of trade privileges on shrimp imports from Thailand since January 1 this year.
Shrimp farming has also been heavily criticised for the widespread
environmental damage it has caused along the coastline.
However, Mr Tanate said he was confident that abalone farming would not run into similar environmental problems. Abalone farms required very clean and clear water, a fairly high initial investment and more patience than shrimp farming. Therefore, abalone farming was attracting a more sophisticated investor, he said.