The IUCN/SSC Shark Specialist Group
Shark News 7: June 1996
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Manta tagging starts in the Maldives
Manta rays Manta birostris are common in Maldivian waters, where
they are a major attraction for tourist divers. Mantas are known to
undertake seasonal migrations from side to side of the Maldivian atoll
chain, in synchrony with the changing monsoons. They also undertake
daily migrations between cleaning and feeding areas, apparently in
phase with the tides. Although this broad picture is known, the details
of the migrations are not.
A proposal to carry out a tagging study of manta movements was
made to the Marine Research Section of the Maldivian Ministry of
Fisheries by an Austrian dive base operator, Mr Norbert Schmidt, in
late 1995. A joint proposal was formulated and tagging trials have
now started. Tags used are 'Floy' spaghetti tags of about 40 cm length,
each individually coded with four colour segments. The tags can be
identified underwater by divers, so the movements of individual
manta rays can be monitored over long time periods.
Initial tagging trials were carried out in February 1996 (during the
north-east monsoon season) in Ari Atoll on the west of Maldives by
Norbert Schmidt and Herwarth Voightmann, another dive base
operator. It was found that the tag head had to be slightly modified,
but once that was done one manta was successfully tagged by a diver
in the water. No resighting has been reported to date. Subsequent trips
to tag mantas in the same area were unsuccessful, either because no
mantas were present, or because other divers were in the water with
the mantas at the same time. An article on the initial tagging trial has
appeared in a popular German diving magazine (TAUCHEN, Hamburg,
May 1996).
Further trials are to be carried out on the eastern side of the
country, near Malé, in September 1996 (during the south-west monsoon
season). If they are successful, larger scale tagging will be carried out
and extensive publicity will be given to the programme in order to
maximise reporting of resightings. An interesting feature of this
tagging programme is that it is being funded entirely by a diving
base operator, because of his interest in manta rays.
R. Charles Anderson, Marine Research Section, Ministry of
Fisheries and Agriculture, Malé, Republic of Maldives.
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