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Thousands of crabs flooded St Thomas beach to shed fertilised eggs - scientist

Published:Wednesday | June 1, 2016 | 12:00 AMJodi-Ann Gilpin
Thousands of crabs come to shore at Rocky Point Beach in St Thomas.

The popular assertion that an invasion of crabs on a shoreline signals that there will be heavy rains or some other form of natural disaster was dismissed by renowned Jamaican scientist, Dr Karl Aiken.

His response follows a recent occurrence at the Rocky Point Beach in St Thomas, where thousands of crabs flooded the shoreline last Tuesday and Wednesday, leaving locals shocked and amazed by the phenomenal sight.

He noted that the only scientific explanation for the occurrence was that the crabs reached sexual maturity and were ready to deposit their eggs. He noted that any other theory was mere speculation.

"Please dismiss that as absolute rubbish. There is no scientific fact to support that kind of nonsense," he declared.

"They made their way to the shore to reproduce. They must shed their fertilised egg in the sea, right at the water's edge and then the fertilised egg goes into nearshore water and hatches, and when those eggs hatch, the larvae comes back to shore. So there's a disconnection with the land, but there's a strong connection with the sea. They then stay on land, grow to adulthood and repeat the process," he explained.

He added, "What I can predict is that in a number of months, I can't tell you how many - there might be an invasion of young crabs coming ashore because when all these adult crabs fall, the fertilised eggs will hatch in the seawater, and if the level of success of hatching is very high, then in a couple of months, they will return to shore by the millions."




The scientist also said he wouldn't be surprised if another major invasion occurs.

"If things continue as they are, there could be another invasion of young, which was what I observed 10 years ago, this very month. St Thomas has a lot of deep water close to shore and they might have a lot nutrients in there that provide what the crabs need," he said.

Identifying the crustaceans as Chinese Mitten Crabs or Shanghai Hairy Crabs, as well as Mango Crabs in local parlance, president of the St Thomas Environmental Protection Association, Appollonia Davidson, told The Gleaner it was abnormal for its type to appear on the coastline.

Davidson said she believed the destruction of the parish's mangroves was a trigger to the sudden appearance of the crabs.

"There's an encroachment on the mangrove areas along the coastline from Leith Hall to Rocky Point; that is the section where the coral reefs used to be. They are no longer there because of the overfishing of the area, and many other factors," she said.