RED TIDE, SHELL FISH DEATHS - SOUTH AFRICA
A ProMED-mail post
Date: Mon, 19 Apr 1999 21:59:04 -0400
From: Marjorie P. Pollack <email@example.com>
Source: Africa News Service, 19 Apr 1999
Mopping up operations continued Sunday at Elands Bay after hundreds of thousands of crayfish beached themselves, causing a major environment disaster. The crayfish began fleeing from a "red tide" Wednesday night. The phenomenon is caused by an enormous concentration of red algae which starves the sea - and crayfish - of oxygen. It occurs because the bacteria that break-up the dead plankton on the sea-bed use up more oxygen in the decomposition process than normal simply because there is a much larger quantity of dead plankton during red tides.
Fish and other marine life can escape the red tide, but the slow moving crayfish are more vulnerable. They head for the shore where the wave action causes oxygen to mix with the seawater. When the tide goes out, many of the crayfish are too weakened from lack of oxygen to follow the retreating tide, and are left stranded.
By Friday night, about 100 tonnes of mainly immature specimens were piled up on the beaches of this fishing resort, some 180 km north of Cape Town. The director of Sea Fisheries declared Elands Bay a marine disaster area and ordered that none of the crayfish be removed. Hundreds of police and navy staff were called in to cordon off the beach to prevent the near riots which occurred two years ago when thousands of visitors attempted to remove the crayfish, a local delicacy.
Although it is unclear whether crayfish affected by red tide are poisonous, people have been warned not to eat any wild shellfish collected anywhere along the West Coast.
Navy personnel took thousands of live crayfish to Saldanha Bay where they were released back into the sea. Although protected, the crustaceans are a delicacy in South Africa and sell for up to 25 US dollars per kg in restaurants.
Two years ago, there was mass walk-out of abount 1,500 tonnes of crayfish. Many live crayfish were then crushed to death in the stampede by the public who went to collect as many of the creatures as possible. Sonya Strydom, manageress of the Elands Bay hotel, said that the town was still recovering from the invasion of crayfish and people two years ago. "If they allow the people to pick up the kreef (crayfish), there will be chaos again like last time," she said in an interview. "People came from all over, even from Johannesburg and Durban. This town is too small to handle thousands of people. They drove their vehicles over people's lawns, over the dunes, they stole dustbins so they could put the crayfish in them. It was terrible," Strydom added.