QUESTION:
I would appreciate hearing from anyone out there that is/was involved in any work on culture of crab (international) and could update me on status, or contacts. Wild seed, Hatchery, Nursery, Growout- etc.
Lorne Clayton
<claytonisg@pacificcoast.net>
COMMENTS 1:
The following is extracted from a Field Survey Report which I carried out in South Korea, near Namhaedo Island, in November 1993, following an oilspill.
At a small indoor hatchery for Swimming Crabs the stock were in six concrete tanks (approx 20 ft in diameter by 6 feet deep), but at the time of my survey they held only a few inches of water. Normally at this time of the year (November) the hatchery would pump around 60,000 liters of clean seawater into the filled tanks every day, to provide the conditions needed by the crabs for producing their eggs, which normally occurs starting in October. The oil contamination of the seawater has prevented the hatchery from operating normally, and none of the crabs has produced eggs. The whole of this season's juvenile crab crop, which would have been available for sale in December, has been lost.
The hatchery produces two types of juvenile crabs for sale to local growers all over South Korea, who stock the subtidal sea bed with them for later capture and sale. The crabs appear to be two species of swimming crab (Portunus), one of which (P. trituberculatus) is particularly valuable locally. The owner sells approximately two million of the lower value species at 200 Won each, and one million of the higher value crab at 500 Won each, his output may vary from two to three million juveniles each year.
The growers get approximately ten times the return from each full sized crab, i.e., 2000 and 5000 Won each respectively. The average annual income from this operation is claimed to be in the region of 500 million Won. Demand is heavy, and the stock is sold as soon as it comes onto the market. The owner estimates that he produces around 20=9925% of the total Korean supply of juveniles for this sector of the fish farming industry.
Doug Cross, Environmental Analyst and Forensic Ecologist
Tel/Fax (+44) 1884 277627
e-mail dcross@mail.eclipse.co.uk
COMMENTS 2:
I am working with the culture of Scylla serrata in SE Asia. There
are no commercial hatcheries that I know of (if you hear of one,
please let me know). There are experimental hatcheries in Australia,
Malaysia, Taiwan and India. There is a lot of mortality between
megalopa and first crab.
Culture is done in small, tidal ponds using juveniles of 2 to 4 cm
purchased from fishers. Growout depends on an abundant and dependable supply of by-catch. Fattening is a very lucrative variation in which recently molted or "water" crabs are held and fed for 15 to 30 days. Females with developed gonads are particularly valued. Main markets are Taiwan, Singapore and Kuala Lumpur. For details see "Report of the Seminar on mud crab culture and trade." Bay of Bengal Programme, BOBP/REP/51 1992. This publication has descriptions of mud crab culture and biology in the Bay of Bengal Region and the Philippines. The companion "Bibliography on the Mud Crab" has quite a few references on biology, culture and marketing. Aquaculture in Taiwan by Chen has a good description of crab culture in the Philippines.
The biggest problems constraining expansion are the lack of reliable
sources of hatchery produced seed, either megalopa or crab and the
dependence on by-catch for feed. The market demand in SE Asia is
terrific and is leading to a depletion of stocks because of the dependence on wild "seed".
The only country that manages its fishery is Australia. The state of
Queensland has a research station at Bribie Island working on
hatchery seed production. The National Prawn Fry Production Center
of the Malaysian Dept. of Fisheries is also doing work on hatchery
rearing.
Charles Angell
<clangell@eskimo.com>
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