Once plentiful and a huge attraction for scuba divers in the Sea, Mantas
haven't been seen in a while.
by Paul Ahuja Manta Mexico
Our third year of Photo-ID based
research on the giant manta rays in the Sea of Cortez was a shocker. No
mantas to photo and none to ID. None. In 2001, 22 mantas were cataloged using
Photo-ID from the research site near Cerralvo Island. The following year 33
mantas in the same location, three of these had been sited the previous
year, giving us a minimum population of 52 animals in two years.
In addition to the 3 individuals
that returned from one year to the next, numerous mantas in each season
exhibited site fidelity of 3 to
4 months with daily re-sights of these mantas
by the research team. Local fisherman say mantas have been swimming here for
as long as anyone can remember. Clearly, this small seamount, had some
significance for this population of mantas.
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However, another possibility
exists which is outside of our ability to monitor at this time. It has been
reported that long-line fisherman may be catching the mantas to use as bait
chunks on the thousands of hooks each boat deploys nightly in the Sea of
Cortez.
Some have suggested the increasing
presence of divers at the research sight would chase away the mantas. We
agree that aggressive divers who try to touch or ride the mantas may chase
them from a location for an unknown period of time.
However, we never sighted mantas before the tourist season began last year
and usually have several months of data before the sport divers arrive.
Logically, if the divers were scaring away the mantas we would have seen
some and then they would leave when the high season came for sport diving.
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But then they disappeared ?
Where had they gone? What may have happened to them?
With the help of Dr. Felipe
Galvan of the Centro Interdisciplinario de Ciencias del Mar ,CICIMAR, we
have spent the winter looking at several possibilities. Last year,
 2003, the
Sea of Cortez was hit by two hurricanes, Ignacio and Marty, over the span of
two weeks in September. The hurricanes may have explained the absence of
mantas in September and certainly decreased our ability to conduct surveys.
However before and after the hurricanes the sea temperatures and conditions
were similar to past years as recorded by the research team and CICIMAR.
 Another strong possibility would
be the absence of food. Mantas consume planktonic animals, especially
Euphasids. Krill is the best known example of this type of animal. The Sea
of Cortez is home to four species of the genus Mobula, a close relative of
the manta that eats the same prey. All four species were present in the Sea
this past year and according to fisheries data, CICIMAR and observations by
the research team the mobulas were in normal abundance. Prey must also be in
normal abundance.
 Fishing, accidental or
deliberate, could account for some loss of population. Again we relied on
Dr. Galvan whose graduate students monitor the fishing camps in the area for
shark and ray catch. There was no increase in manta catch according to this
data.
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Click to expand the
fabulous images in this article.
We encourage our readers
to make a donation to IEMANYA OCEANICA and Manta Mexico. Please help
make a difference before it is too late! |
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Additionally the divers act as back-up for the research team informing us
when they have seen mantas and many times have usable photos of the mantas
they saw. Not one single sport diver from the six dive shops in the area
reported seeing a manta last year.
While we struggle to solve the
mystery of last year we prepare for the 2004 season which begins in June. In
past years this is the month when mantas have been first sighted. We welcome
your participation in the project and thank you for your interest.
Good News for Mantas!
IEMANYA OCEANICA, a non-profit
501(c)3 based in California that conducts shark and ray research in the Sea
of Cortez has partnered with Manta Mexico.
This allows our research project
to receive cash donations from the U.S. which will be tax-deductible for the
donors. Donations in any amount should be sent to: IEMANYA OCEANICA C/O
LALEH MITCHELL 5190 E. BROMELY DR. OAK PARK, CA 91377.
Please attach a note explaining
that donation is for Manta Mexico and the money will be passed on to the
project and you will receive your tax deduction information from Ms. Laleh
Mitchell of IEMANYA. For more information about IEMANYA OCEANICA and their
work please visit
www.IEMANYA.org on the internet. For
questions or comments on this bulletin please write to
mantamexico@hotmail.com
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No
this sign does not mean topless bar ahead! Topes are speed restricting
obstacles placed to slow traffic in populated areas. Along Highway 1 most of
the Topes give plenty of advanced warning, some more than 500m. The tricky
ones however, can be the second or third in a series, just when you think
it's safe to pick up the pace.
One
of the most devastating encounters I recall with a Tope was on my first drive
down Baja. Just past the long straightaway of the Santo Tomas vineyards my
co-pilot was frantically searching the Spanish/English dictionary. It was the
hope that TOPE meant some kind of specialty restaurant when our heads against
the roof of the car made the translation for us. As if that was not bad
enough, it was punctuated with the sounds of chassis and radiator against
pavement. It seemed no coincidence there was a radiator and transmission shop
within yards.
Just as a side note, I noticed that my infamous Tope had been mellowed and
rounded on my August drive. But beware! These guys can bite!
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