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Biologist devoted to preserving terrestrial crabs in central Vietnam

Monday, February 02, 2015, 14:34 GMT+7
Biologist devoted to preserving terrestrial crabs in central Vietnam
Two individuals of the "Gecarcoidea lalandii," a large species of terrestrial crabs

For more than a decade, a Ph.D. holder has dedicated himself to promoting the sustainable exploitation of a variety of terrestrial crabs, which are indigenous to a UNESCO World Biosphere Reserve in central Vietnam, and improving the income of locals.

>> An audio version of the story is available here

Dr. Chu Manh Trinh, 53, has frequented Cu Lao Cham (Cham Islands,) which are located off Hoi An City in the central province of Quang Nam, for the past 11 years.

For all those years he has been engaged in research on “Gecarcoidea lalandii,” a large species of terrestrial crabs, which are dark purple in color and have long legs and short pincers.

The crustacean is nocturnal, and spends most of the day hiding in burrows.

Adults are mainly found in forests and other open areas. When carrying eggs, females instinctively migrate to the coast where they release the eggs in the tidal zone. 

Dr. Trinh, who has become a household name to the island’s population of around 3,000 people, is credited with studying the crabs comprehensively and saving them from extinction.

His massive contributions are also believed by local officials and residents to have helped earn Cu Lao Cham Marine Park, which incorporates the cluster of islands, UNESCO recognition as a World Biosphere Reserve in 2009.

The islands, also recognized as one of Vietnam's national scenic sites, offer several stunning beaches and forested hills as well as a wide array of tourist services such as camping, swimming and scuba diving.

However, the islands were not so gorgeous over a decade ago.

Fruitful dedication

After graduating from universities in the U.S. and Netherlands, Dr. Trinh returned to Quang Nam Province, where he worked in the forestry sector.

In 2003, he arrived in Cu Lao Cham for research on biological diversity, and has been infatuated with the islands’ charms since.

“When I first came here, the islands were teeming with life and aquatic creatures. The territorial crabs crawled in hordes on cliffs and scratched across roofs during the night,” Dr. Trinh recalled.

The islands back then were littered with nylon bags and sea animal carcasses and reeked of dried seafood.

He then embarked on a long-running mission to improve the environmental awareness of locals and enhance the islands’ allure to tourists.

The scientist was gravely concerned upon seeing locals catch the crabs unsustainably without sparing even young or pregnant ones.

They were sold for around VND200,000 (US$9.3) per kilogram.

The crabs, which have good flesh and smell of forest leaves, were on the brink of extinction then.

He advised locals to catch fewer crabs and was instantly met with vehement objections.

After several sleepless nights, Dr. Trinh conceived a project to preserve the crabs and enhance their economic value.

His project recevined support from the local government, which soon released a decree.

The decree stipulated that only crabs whose shell measures at least 7 centimeters can be harvested.

The crabs are supposed to bear a management agency’s quality stamp before being sold on the market.

Catches are limited to around 10,000 crabs a year, with harvesting performed in a fixed season and in different areas to keep the crustaceans from dwindling in number.

A kilogram has a floor price of VND500,000 ($23.)

Dr. Trinh set up a crab catching team comprised of 30 local households to begin with.

“Crabs with shells measuring 7 centimeters are typically around 14 years old. Their flesh is of higher quality at that age and thus fetches high prices. Moreover, most crabs have had offspring by that age, which eliminates the risk of extinction,” Dr. Trinh explained.

Catchers later raised the price to VDN700,000 ($32.62) per kilogram, while restaurant owners offer their customers the delicacy for VND1.2 million per kilogram.

As the catchers, dealers and restaurant owners all benefit, the preservation of the crabs has improved notably.

Nguyen Van Nga, a member of Dr. Trinh’s crab catching team, stressed that but for the scientist’s tremendous assistance and guidance, the crabs would have long been a thing of the past.

“Catching crabs is now our steady unseasonal source of income. Roughly 7,000 crabs were harvested last year, which accounted for only one fourth of the total number. We’re glad to see the crustacean proliferating and always refrain from catching young ones,” he noted.

According to Tran Tan Dung, a local official, locals harvested and gave biological quality stamps to a total of 9,486 crabs in 2013 and 2014, with the number of males doubling that of females.

After years of field research, Dr. Trinh observed that “Gecarcoidea lalandii” is an incredibly smart species.

Crab catchers often see pairs of “lovers” contemplating the moon, while crab farmers sometimes see them climb onto one another’s shells to escape from containers.

To his delightful surprise, the scientist also discovered that male crabs have a large pincer and a significantly smaller one.

The “guys” always use their small pincer to pick up food, while using the other big one to fight and keep their mates.

Dr. Trinh stressed that he will continue to frequent Cu Lao Cham and bond with the crabs until he is no longer fit enough to do so.



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