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The
2007 whale shark season in
Seychelles
was yet again another successful season and not without
its share of surprises. The programme was once
again sponsored by the Save Our Seas Foundation and run in
coordination with the University Marine Biological Station
Millport (
University
of
London
). One
of the high points was the re-identification by the IRIS
photo ID program of a shark on
the
11th of September 2007
that was originally tagged in October 2001, almost exactly
six years later. Other surprises were less pleasant as it
soon became apparent that the number of whale sharks in
the area was significantly lower than in previous years,
the aerial sighting count for 2007 was only 1.9 sharks per
hour of aerial survey up to October 19th, the lowest
recorded since systematic aerial surveys began in 2001.
This
low level of shark abundance was in marked contrast to
that of 2006 when the sighting rate was 6.13 sharks per
hour, the record so far. The apparent decline in the
numbers around Seychelles is, however, not necessarily
indicative of a real decline in the population of whale
sharks in the region; for many years the numbers of whale
sharks seen off the coast of South Africa has been very
low and strandings along the East coast have been
non-existent. In 2007, the number of whale sharks seen
increased dramatically with aerial surveys by the Natal
Sharks board documenting 50 sharks along the South African
and
Mozambique
coast and at least six whale sharks were stranded along
the coast during this season. As such it may well be that
the
Western
Indian Ocean
population was concentrated more towards the African coast
this year than in previous years.
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Whale
shark as seen from the micro-light survey. Photo
MCSS.
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Overall
a total of 50 boat trips were run during the course of the
season resulting in a total of 267 in-water encounters and
average of 5.34 whale shark encounters per trip; of the 50
trips only two failed to find whale sharks and on both
occasions the micro-light had been forced to return to
base due to inclement weather. Once again, this impressive
encounter rate could not have been achieved without the
dedication of our two micro-light pilots, Johan Anderson
and Guy Blain, and the seeming limitless enthusiasm from
the volunteer monitoring team.
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Katie
'don't bother me I'm concentrating!' kept
encounter data up to par this season. Photo
MCSS |
The
volunteer monitoring team this season was ably organised
by Katie Brooks, who was also with us in 2006 and had just
completed the whale shark season in Ningaloo as a whale
shark guide with Ningaloo Blue dive centre. In total nine
volunteers participated in the programme and despite the
lower number of sharks all were kept very busy entering
the data and updating the photo identity database on an
almost daily basis. In total, some 2513 digital photos
were processed resulting in 442 identity fingerprints that
came from a total of 88 individual sharks. Of these, 37
had been seen in previous years (42%); this high
resighting rate is indicative of a site faithful
population and indicates that a large proportion of the
whale sharks around
Seychelles
can be considered as ‘resident’ at least for several
months of each year.
This
season we also welcomed visiting whale shark researcher
Mark Meekan from the Australian Institute of Marine
Science along with his family and a film crew who will be
producing a documentary for the BBC about whale sharks (see
article this issue). Several other film crews also
visited and it was a pleasure to finally get the Save Our
Seas High Definition Video cameraman Dan Beecham into the
water with some
Seychelles
whale sharks; SOSF is producing an HD video documentary on
the work supported by the foundation and the
Seychelles
whale shark programme is one of the key projects.
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