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Foraging
Grounds
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©2006 MEDASSET, Photo: V. Kouroutos
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Foraging grounds play an important part in the sea turtle
life cycle. After hatchlings exit the nest and make it
safely to the sea, they swim in a frenzy to reach the
open sea. The ‘lost years’ is the little-known
period when young sea turtles stay away from land until
they become juveniles. Young turtles develop specialized
feeding habits and areas, which vary between species.
These are the foraging areas or over-wintering areas where
they find food and refuge.
In the Mediterranean nesting occurs only in the eastern
basin (Turkey, Greece), whereas the western basin (Tunisia,
Libya, France, Italy, Malta, Spain) is predominantly used
as a foraging ground and possibly, as developmental habitat
for juvenile turtles.
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In
MEDASSET’s 2005 Rapid Assessment Survey of important
Marine Turtle and Monk Seal habitats in the coastal area
of Albania; Fishermen, using different types of gear,
provided details of their by-catch, sightings and most
recent encounters with turtles. By-catch data showed a
marked difference in the number of turtles captured annually
between the north and south of Albania. Typical catches
per fisher per year were 2-6 turtles south of Durres,
and 100-250 turtles in the north. Juveniles were mainly
captured in shallow waters <10m (trawls, nets, long-lines,
and stavnike) during April-May, which suggests that an
important foraging habitat for juvenile loggerheads may
exist in northern Albania.
For the full report visit press here.
In
a study undertaken by Dr Broderick of the University of
Exeter and her team twenty green and loggerhead turtles
were tracked nesting at two beaches on Cyprus, using satellite
transmitters. All females tracked for more than six months
remained in the same foraging grounds, moving to deeper
water for the winter where they conducted dives of up
to a record breaking 10.2 hours. Five females were also
tracked when they nested again up to five years later
and returned to the same foraging sites. Green turtles
have been observed cropping sea grass gardens to encourage
new growth, (The only member of Cheloniidae to forage
on sea grasses, these turtles play an important ecological
role as their grazing of the sea grass stimulates new
growth while their feces replenish nutrients to this ecosystem)
so there could be a benefit to them returning to foraging
grounds. Loggerheads have an omnivorous diet, including
molluscs and crustacea, so the benefit to them revisiting
feeding areas is unclear. Scientists do not yet know why
this behaviour has evolved, but it is possible that sea
turtles are territorial or are responding to limited food
resources by sticking to their own feeding patches. ScienceDaily,
26/4/2007
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