Central
Coast of Peru
Photo-Identification is a very valuable research
tool used for studying a range of whale and dolphin species. Researchers
take photographs of naturally marked animals - for bottlenose dolphins
they concentrate on taking photographs of their backs and dorsal fins
because this is where the dolphins often have long lasting nicks or
scars on their bodies.
Bottlenose dolphins are particularly well
suited to the process of photo-identification. The thin posterior edge
of the dorsal fin (trailing edge) becomes "notched" during
interactions with conspecifics, predators, and humans, often resulting
in recognizable patterns of nicks, scars, and notches. Other individual
characteristics taken into account are the fin shapes and pigment patterns
such as fungus. A well-marked dolphin is one that is recognized by more
than one single feature. Such patterns are analogous to human fingerprints
and are unique to each individual. Notch patterns once acquired by a
dolphin are usually permanent with little change occurring over time.
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Different distinctive shapes of dorsal
fins from very curved and pointed to triangular and finally
straight.
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Distinctive features on dorsal fins:
Left picture: tooth rake mark parallel to the leading edge,
white patches and small nicks in the trailing edge.
Middle: deep notch in the tip and deep notch in the trailing
edge
Right: three nicks in the lower part of the trailing edge
of the fin, leading edge shows a humpback like curve, light
brown colored scratches on left side of fin.
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However, if the markings on a dolphin change
significantly, it can be difficult to identify him as the same individual.
This way, that some dolphins might not be identified correctly after
a while and seem to disappear, as it is impossible to link the two sets
of pictures. The dolphin would then be classified as new individual.
Thus the same animal may appear in the database more than once. Therefore
we are applying a series of methods to match the pictures and the database
is in a constant review process and will be permanently updated in order
to reduce this kind of mistake.
Photo-id can be used to follow the progress
of individual dolphins and study their health, social behavior, movements
and reproductive patterns. It can also be used to estimate the size
of the population. Scientists are able to work out which dolphins have
been traveling and/or feeding with one another, they can work out which
dolphins are socializing together and playing together, and they can
report back on new dolphin births.
Finally, they can report if one of the dolphins
has not been spotted for a period of time. Of course, if the body of
a dolphin is found, it is often possible to determine which animal it
is that has died. More often though, a particular dolphin will just
disappear from the population without trace. Usually one then has to
assume that the dolphin has died, either through natural old age or
more likely as a result of becoming entangled in a fishing net or being
killed illegally by a fishermen in order for his meat to be sold for
human consumption or the used as bait.
Photo-Identification research is a long-term
approach to understand dolphin ecology. The Marine Mammal Research Program
(MMRP) of Texas A&M University at Galveston for example has been
conducting studies on bottlenose dolphins along the Texas coastline
since 1990. The MMRP has now identified over 1,500 individual bottlenose
dolphins from Texas coastal waters, and this number is expected to approach
2,500 once data analysis is complete. Members of the MMRP have also
assembled identification catalogs of bottlenose dolphins from Argentina,
Costa Rica, California and Baja, Mexico totaling well over 3,000 individuals.
Mundo Azuls photo-identification project
aims to cover the entire area of the central Peruvian Coast between
Chimbote and Paracas (approximately 700 km) during the next few years.
This year we started with two first research areas: the
coastline between Lima and Asia Island and the coastline
north of the Paracas National Reserve.
You are able to take active part and
financially support our research program by:
Adopting a dolphin
Give a name to your favorite dolphin
Become a dolphin conservation volunteer
Go dolphin watching
If you want to know more about how to identify a dolphin, click
here.
