April 25, 1998
A spokesman for the Department of Health said today (Saturday) that the department had stepped up the sampling and testing of seafood and shellfish since the occurrence of the recent bloom of red tides on March 20.
A number of samples had been collected from fish culture zones and retail markets in Hong Kong for testing.
The spokesman said that the effort would be further strengthened in view of the discovery of different kinds of algae in the latest bloom.
He pointed out that the test results of samples collected since March 20 indicated that they were all within safety levels.
"A total of 132 samples have been collected. Results of the 111 samples available so far showed that only nine contained some toxins, which were well within the safety levels".
The spokesman explained that seafood samples sent for testing by the University of Hong Kong underwent a mouse toxicity test. This was a recommended screening method for testing marine toxins in fish and shellfish.
From the food safety point of view, the safety limit of 4 000 mouse unit per kilogram for shellfish is applicable to various types of toxins, including toxins causing Paralytic Shellfish Poisoning (PSP).
However, the Department of Health considers that for the time being, it is advisable to avoid eating bivalve shellfish which poses a much higher risk than fish.
Members of the public are advised to buy fresh fish for consumption.
The Department of Health and the Agriculture and Fisheries Department will continue to closely monitor the situation and update the public when necessary.
In response to press enquiries on Alexandrium excavatum, a spokesman for the Agriculture and Fisheries Department said that the toxic algae was not a dominant species in the water samples collected from three beaches - Repulse Bay, Chung Hom Kok and Middle Bay, which have been affected by the red tide.
The spokesman said: "Alexandrium species is only one of some 10 different algae species found in the samples. It does not constitute a significant percentage in the water samples cell count in all three samples.
"It is not a new species and it has been found to be present at a low level in Hong Kong waters during the months of March to May in past years."
The spokesman noted that so far, no fish kill or abnormal circumstances had been reported in all fish culture zones in connection with the red tide bloom.
Nevertheless, operators of fish culture zones in various parts of the territory have been alerted to the need to take precautionary measures.
The department had also examined water samples taken from the three beaches in question and informed the Department of Health, the Environmental Protection Department and the Urban Services Department of the results.
As a precaution to swimmers, the red flag remains hoisted at the three beaches. Member of the public are advised not to swim at there.