The National Environment and Planning Agency (NEPA) said there is no reason to be alarmed by the recent crab invasion in St Thomas where thousands of the crustaceans with black-and yellow-hued heads and reddish-purple legs swarmed the Rocky Point seashore.

Residents of Rocky Point and other Jamaicans who had seen pictures and videos of the massive cast of crabs had expressed shock and fright at the sighting of the crabs, identified as Chinese Mitten Crabs or Shanghai Hairy Crabs.

But Dionne Rose, manager, public education and corporate communication at the agency, said land-to-sea migration and vice versa are normal parts of the animal’s reproductive cycle.

She said similar events were witnessed a decade ago in Nine Miles and Bull Bay, both also in St Thomas.

“During the events, hundreds of juvenile crustaceans traversed the beach from the sea to the adjoining mangrove forest. What is now occurring is that the adult females are traversing the beach en route to the sea as part of their reproductive life cycle,” Rose explained.

“Ecologically, the black land crab plays a role in soil dynamics and nutrient cycling in the environment. The public is therefore encouraged not to harvest the egg-laden adults as this will negatively impact the population of the species,” she added.

Rose said that after mating, the female crab carries her eggs for about two weeks before migrating and releasing them into the sea. During the peak of the spawning period the land crab then moves to the sea along a migratory route that includes roadways, gullies, beaches and mangrove areas, causing it to appear as a mass migration.

The crabs then lay their eggs near the sea, incubate them for approximately two weeks, and then enter the sea briefly for the larvae to hatch. The larvae released into the sea must drift and develop for about 20 days and if the currents are favourable, those that are lucky to survive come back to shore to migrate inland to continue their life cycle, Rose explained.

But residents, most of whom had witnessed the phenomenon for the first time, had different theories.

“Last week Thursday, the beach full a crab. Yuh see crab ’til you stomach sick,” fisherman Alphanso told the

Jamaica Observer last week Monday. “A di fus mi really see it, but mi hear a man say him see it already.”

According to him, the heavy rains that had lashed the parish drove the crabs out of their habitat in the nearby mangroves, forcing them to squat on the beach for two days.

“A di rain wash dem out. A water full up dem hole, so some a dem find hole pon de seaside,” he said.

Another fisherman, who identified himself only as Michael, added: “Practically every year dem come out plenty round da time yah, but dis time dem march out inna millions. But dem march gone back een now.”

“The only explanation is the weather. Yuh know like it is a sign dat say wi ago have heavy rain or hurricane,” he continued.

The mass crab sighting also amazed James, yet another fisher.

“De amount a crab dat did deh yah, three 10-wheeler truck caa move dem, you affi have more,” he said with a chuckle.

The amazement was, however, lost on bartender Nicky, whose establishment is located on the beach.

“Mi did frighten cause a di fus mi ever si so much crab in my life! Some small and some big, but mi hear say some people ketch some and eat dem,” she said.