After about 30 years
of maturing an adult female sea turtle returns to the land to
nest, usually on the same beach from which they hatched. This
can take place every two to four years in maturity. They make
from four to seven nests per nesting season. They dig a hole with
their hind flippers and lay from 100 to 150 eggs in it (depending
on the species) before covering it up and returning to the ocean.
Some of the eggs are unfertilized 'dummy eggs' and the rest contain
young turtles. Incubation takes about 2 months. When the eggs
hatch, these baby turtles dig their way out and seek the ocean.
Only a very small proportion of them (at most 1 in 100) will be
successful, as many predators are waiting to eat them.
Sea turtles of
all species are endangered. The Leatherback, Kemp's ridley, and
Hawksbill turtles are listed as Critically Endangered. The Olive
ridley, Loggerhead, and Green turtles are considered Endangered.
And the Flat back is considered Data Deficient due to lack of
research. They used to be hunted on a large scale in the whaling
days for their meat, fat and shells. And coastal peoples have
always gathered turtle eggs for consumption. These days though
their biggest threat comes from long-line fishing, and as bycatch
in shrimp nets, as well as over development on nesting beaches.
Each year it is said that 40,000 turtles die from longlines alone.
According to researchers at the 24th Annual Symposium on Sea Turtle
Conservation and Biology, in Costa Rica the Pacific Leatherback
has ten years before extinction if nothing is done to reverse
these problems. Small and inexpensive changes to fishing techniques,
such as slightly larger hooks and traps from which sea turtles
can escape, can dramatically cut the mortality rate.
1-6 US Fish & Wildlife Service
7-12 National Undersea Research Program