Mystères des bas-fonds
Le Groupe de travail sur la tortue luth.
La tortue luth peut avoir les dimensions dun lit double et peut peser près
dune tonne. Elle peut plonger plus dun kilomètre sous leau et maintenir
une température corporelle jusquà 18 degrés C au-delà de la température de
leau ambiante. Elle naît en Amérique du Sud et en Amérique Centrale et ne mange
que des méduses. Une portion de la population des tortues luth, qui est en déclin de
façon alarmante, passe l'été à proximité des côtes de la Nouvelle-Écosse.
La tortue luth est le plus gros reptile du monde.
« Ce nest quà partir des années soixante que des chercheurs ont
commencé à documenter la présence de la tortue luth ici ; et même à ce moment
personne navait fait détudes approfondies sur elle », constate Mike
James, coordinateur du Groupe de travail sur la tortue luth, un groupe qui veut en
apprendre davantage sur la tortue et sur ses déplacements dans les eaux de la
on this article
Mystery of the Deeps
For the Leatherback Sea Turtle Working Group
hey can grow to the size of a double bed and weigh up
to a ton. They can dive more than a kilometer into the sea, and they maintain body
temperatures as high as 18 degrees C. above the surrounding water temperature. They eat
only jelly fish. They are born in South and Central America, and a portion of their
declining population spends the summer off the coast of Nova Scotia. The leatherback
turtle is the worlds largest reptile, and one of its most mysterious.
(photo: Vern Skalpsky, North Atlantic Leatherback Turtle Working Group)
Female leatherback nesting on Trinidad Beach
"We know very little about the basic biology of leatherbacks
their growth rates, their reproductive behavior, their life span," says Mike James,
Coordinator of the Leatherback Sea Turtle Working Group, which is interested in finding
out more about the turtles, including their distribution in Nova Scotian waters. "We
dont fully understand their ocean travel routes, and we have no idea where in the
open ocean the juvenile leatherbacks are. There are no records of small leatherbacks at
"Researchers only began documenting the leatherbacks presence here in the
1960s, and even then nobody did in-depth studies on the turtles," says James.
"Fishermen have always known that leatherbacks are part of the marine environment in
Atlantic Canada, but nobody has asked them to contribute to research on the animal until
The Leatherback Sea Turtle Working Group depends on information from fishermen, because
they encounter the animals more than anyone else. James has spent the last five months
travelling throughout coastal communities in Nova Scotia talking to fishermen about
leatherbacks, as well as to school children and operators of whale and seabird tour boats.
The contacts he has made so far have been encouraging. Not only have many people
volunteered to help with the project, but many have also reported past sightings.
(photo: Lindsay Hatcher, North Atlantic Leatherback Turtle Group)
Adult turtle (swimming off Cape Breton, N.S.,
One thing he learned was that there were a large number of leatherbacks
feeding in Shelburne Harbour last August. "That kind of phenomenon has only been
documented a few times for this species," says James enthusiastically, "and it
occurred here. Thats significant. Its possible that there were more
leatherbacks off Shelburne last year over the course of three days than we had previously
thought would come to the province in a year."
Biologists used to think leatherbacks found in Nova Scotian waters were individuals
that had strayed from their southern habitat as they followed the Gulf Stream in search of
jellyfish. "But we now believe that isnt so," explains James. "The
animals that are here mean to be here, because they know they can find lots of
jellyfish here. And the turtles are here every year. But apart from knowing that
leatherbacks eat jellyfish, we still know very little of their habits in the North
The number of leatherbacks that come to Nova Scotia, and where precisely they go when
they get here, is so far unknown, but James is optimistic that the information hes
receiving this summer will help him begin to answer these questions. "Weve
recorded 34 new leatherback sightings already, and its only July," he says
excitedly. "Its August thats the peak leatherback month in our
James attributes a large part of the Leatherback Sea Turtle Working Groups
current success to people who have volunteered to put up its distinctive blue-and-yellow,
"Have You Seen This Turtle?" posters across the province, and to those who have
gotten the word out to people in coastal communities. The Working Group is interested in
all sightings of leatherbacks, alive or dead. Anyone who has seen one should record the
date, time, and location of the sighting as precisely as possible, the sea and weather
conditions at the time, and , if possible, the water temperature. The Group would also
appreciate any photos that might be taken of the turtles.
To report a leatherback sighting, or if you are
interested in taking part in or learning more about any aspect of the project, please call
Mike James toll-free, at 1-888-729-4667.