Satellite tracking is used to trace the migratory route and feeding ground of a Green Turtle by the Agriculture, Fisheries and Conservation Department (AFCD) for the conservation of this highly endangered species.
"This is the first time Hong Kong applied this technique to trace a Green Turtle," AFCD Nature Conservation Officer Mr Simon Chan Kin-fung said at a media briefing today (November 9) on the conservation work and breeding result of Green Turtles in Hong Kong this year.
"A satellite transmitter was attached to the back of a female Green Turtle by AFCD staff after it laid eggs at Sham Wan, Lamma Island on August 9. The released turtle then headed southwestward along the coastline of the South China Sea to her feeding ground at a speed of 0.5 to 2 kilometres per hour.
"The Green Turtle took about 20 days to reach Hainan Island, over 500 kilometres away from Hong Kong. It stayed in the coastal waters off the eastern part of the island where it fed and swam in the shallow waters," he said.
Green Turtles are a special group of marine reptiles and are remarkable for their migratory behaviour. They spend most of their time in shallow water feeding ground. During the breeding season, instinct drives mature turtles to travel hundreds or even thousands of kilometres from their feeding grounds back to their natal beach to lay eggs.
"Green Turtle is the only species of sea turtles that breeds in Hong Kong. Its only existing nesting site in Hong Kong is at Sham Wan. Before AFCD carried out the satellite tracking programme, we did not know where its feeding ground was and which migratory path it followed.
"After the satellite transmitter was attached to the Green Turtle and it started its journey back to the feeding ground, it was exciting to receive the first satellite signal from the migrating turtle. We are still receiving signals from the turtle in her feeding ground until the battery in the transmitter runs out or the transmitter is detached from the turtle's carapace naturally later.
"Signals from the transmitter indicated that the Green Turtle usually dived for 15 to 30 minutes to eat sea grass and sea weed and surfaced up to breathe before the next dive. Sometimes it stayed underwater for as long as an hour, possibly sleeping inside rock crevices or hollows. The Green Turtle is expected to stay in the feeding ground and may come back to nest in Sham Wan three to five years later," Mr Chan said.
To enhance the conservation work on local Green Turtles, he said it was very important to trace their migratory routes and feeding grounds to draw up the necessary protection measures and seek co-operation with relevant authorities. In this regard, AFCD had strengthened regional co-operation with relevant authorities in the Mainland.
"Last year, AFCD worked with its counterparts in the Guangdong Ocean and Fishery Bureau in conducting a satellite tracking project for three Green Turtles at Gangkou National Nature Reserve. The satellite signals indicated that two turtles travelled to Hainan Island and one to Okinawa, Japan.
"Other measures for the conservation of the South China Green Turtle include the exchange of nesting information, scientific studies and staff training," Mr Chan said.
Regarding the breeding results of Green Turtles in Hong Kong for this breeding season from June to October, he said AFCD found six clutches of Green Turtle eggs at Sham Wan. It was estimated that over 500 eggs were hatched naturally and successfully.
Mr Chan urged members of the public to report any sighting or stranding of sea turtles to AFCD on 1823 so as to help protect this endangered species. On the other hand, vessels should avoid entering the sea inlet of Sham Wan during sea turtle breeding season so as to minimise any potential disturbance to the sea turtles.
End/Saturday, November 9, 2002