Helping nature

A Thai farming project aims to raise more crabs to sell as U.S. researchers look to replenish the bay's breeding stocks

April 30, 2006|By GADY A. EPSTEIN | GADY A. EPSTEIN,SUN FOREIGN REPORTER

TRANG, Thailand -- Working in a light drizzle at low tide, Wallop Suwanno clambers from his small boat onto the roof of a wooden tank just offshore, lowers a plastic bucket holding four egg-bearing female crabs and dumps them into the water.

The females, each carrying about a half-million fertilized eggs, have been spared for now so they can breed. Twenty-two small crabs have received a similar reprieve so they can grow larger in a neighboring tank.

All of these blue swimming crabs are to eventually end up being sold and eaten, but Suwanno and a fellow fisherman are willing to wait because of a Thai government program.

"It's a good thing to do to return something to nature," said Suwanno, 35, wearing a shirt that read on its back, in both Thai and English lettering, "Crab Project in Trang."

The fishing here used to go as natural conditions dictated. When the tide was high enough, wives helped their husbands pull their boats into the water, the small wooden craft loaded with crab traps to reap what nature sows.

But the fishermen, worried about declining crab catches, are no longer leaving the harvests of blue swimming crab to nature alone. Government experts have encouraged these fishermen to become farmers as well, raising crabs in tanks, as if the crustaceans were domestic livestock.

If the fishermen succeed, it would also give hope to their counterparts in the Chesapeake Bay. Because unlike shrimp or salmon, most crab species have long been considered impossible to domesticate. They are feisty and cannibalistic, killing their own to survive in close quarters. They generally don't thrive by passively accepting food.

In Thailand, the goal is to raise more crabs to sell for consumption and to reverse a decline in the crab's population in Thai waters. In Baltimore, researchers at the University of Maryland Biotechnology Institute are focused on finding a way to replenish the Chesapeake Bay's vastly diminished breeding stocks. Steve Phillips - whose family's restaurant chain long ago turned to Asian crabmeat as the bay's production declined - has donated $300,000 to the local project.

Yonathan Zohar, director of the institute's Center of Marine Biotechnology, said he is encouraged by the survival rates of homegrown blue crabs.

The Maryland blue crab and the Thai blue swimming crab are different species, but they exhibit a similar aggressive hunting instinct developed over millions of years. Confining them in farms would seem a challenge to evolution.

But Thailand, for many years the leading shrimp-farming country in the world, is determined to make blue crab farming work.

Marine biologists have created hatcheries to try to collect and release the roughly half-million eggs that each female spawns when breeding. In some test farms, biologists use mosses and seaweed along the seafloor so that young crabs can hide from combative neighbors. Scientists are also studying the blue swimming crab's DNA, in the hope of breeding the animal selectively to reduce its aggressiveness and increase its consumption of food pellets.

"We have to find some means to help the fishermen," said Banchong Tiensongrusmee, coordinator of a blue swimming crab program for the Thailand Research Fund.

It's unclear whether these steps will work, but without government intervention, fishing communities like this one in Trang face a difficult future.

At the end of a sandy road, hard by the water, the 120 people of this community live little better than past generations, in plank houses on stilts, with hot plates to cook meals and little or no furniture. Fishermen wake up according to an internal alarm clock, usually before dawn, to go out and catch crab.

They're catching less than in the past. On a recent day, the eight boats that went out returned with about 6 pounds of crabs each, a paltry catch. Thailand's total catch of blue swimming crabs had more than doubled in 13 years - because of an expanding local market and the new demand for exports - from less than 25,000 tons in 1985 to more than 50,000 tons in 1998, before the decline began.

One change for these fishermen is that if the catch includes a breeding female - her eggs bunched together in an orange-hued paste - that crab goes to the farm instead of a steamer. If the catch includes crabs too small to have much meat, they also go to the farm. Someone records the fisherman's name so he can reclaim an equal number of crabs in exchange. In return, the female crab is allowed to lay her eggs, and the young crabs are allowed to grow.

In the early stages of a blue swimming crab's life, man is kinder than nature. In the wild, an egg released from a female crab will hatch and the larva takes up to 30 days to move to a nursery ground, during which time it grows into an inch-sized crab. Of the half-million fertilized eggs a female may release, 99.98 percent of the offspring will die without reaching the nursery ground.

Government fisheries experts decided to raise the odds.

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