Animals

Burlap Highways Give New Taipei's Migrating Mitten Crabs a Leg Up

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By Scott Huang/Ted Chen/Bryn Thomas

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At the Bitan waterfront in New Taipei, volunteers are laying out burlap sacks to help juvenile mitten crabs climb past concrete weirs to migrate upstream. Water resources expert Yu Chin-yu says the crabs climb the material five to ten times faster than plain concrete, with algae on the sacks providing an added food source along the way.

Crab Conservation

REPORTER:
The Bitan waterfront is a popular leisure spot in New Taipei — known for its scenic river and rowboats.

But today, volunteers have their eyes on something smaller.

They’re preparing burlap sacks to help some local critters.

These bags, decorated with care, will serve as a highway for juvenile mitten crabs to migrate upstream and grow up.

REPORTER:
It’s a journey made harder by manmade structures like concrete weirs.

For crabs just a few centimeters wide, they’re towering obstacles.

Yu Chin-yu (WATER RESOURCES EXPERT):  
It gives them something to grip while climbing. Over the same distance, they climb burlap five to ten times faster than plain concrete.

REPORTER:
Algae growing on the sacks is an added bonus for the crabs — giving them something to eat on the way.

Once fully grown, these crabs will return downstream to breed.

Volunteer:  
The mitten crab can crawl in a straight direction.

Yu Chin-yu (WATER RESOURCES EXPERT):  
That’s right! Since they are still small they can crawl straight, sideways or backwards as their shells haven't hardened yet.

REPORTER:
River pollution across Taiwan has eased in recent decades — letting mitten crabs expand their range. Fish have long had migration channels here. Now, thanks to a few volunteers, Bitan's crabs can claw their way to a brighter future.

Scott Huang, Ted Chen and Bryn Thomas for TaiwanPlus.