赤蠵龜和欖蠵龜
在北太平洋中央的覓食與棲地洄游
Forage and migration habitat of loggerhead
(Caretta caretta) and olive ridley
(Lepidochelys olivacea) sea turtles in the
central North Pacific Ocean
JEFFREY J. POLOVINA,, GEORGE H. BALAZS, EVAN A. HOWELL, DENISE M. PARKER, MICHAEL P. SEKI AND PETER H. DUTTON
Fish. Oceanogr. 13:1, 36–51, 2004
Reporter : Yu-Tong He
A brief introduction of loggerhead
sea turtle & olive ridley sea turtle.
Why do this research ?
8
http://www.seaworld.org/infobooks/SeaTurtle/stclass.html
Kindom: Animalia
Phylum: Chordata
Subphylum: Vertebrata
Class:
Reptilia
Subclass: Anapsida
order:
Testudines
Suborder: Cryptodira
Superfamily: Chelonioidea
family: Cheloniidae
genus: Caretta
species: Caretta
wikipedia
The top (dorsal) color is reddish brown
with dark streaks
 The body length is 82 to 105 cm (32-41 in.) .
 Have an average weight just 66 to 101 kg
(146-223 lb.).

Kindom: Animalia
Phylum: Chordata
Subphylum: Vertebrata
Class:
Reptilia
Subclass: Anapsida
order:
Testudines
Suborder: Cryptodira
Superfamily: Chelonioidea
family: Cheloniidae
genus: Lepidochelys
species: olivacea
www.worldwildlife.orgturtlesspeciesort.cfm
It is named for the olive color
of its heart-shaped shell.
 Have an average weight just over
100 lb (up to 50 kg.) .
 Olive ridleys are regarded as the most
abundant sea turtles in the world
 Carapace length of only 27 inches (70 cm).
 With Kemp’s Ridley the smallest species.

We investigated the oceanic habitat and movements of
these 2 species because they caught by longline gear .
http://www.tortugamarina.org/downloads/images/coco-hookmouth.jpg
Circle hook is better than J hook.
http://www.globalresponse.org/gra.php?i=
/
2
03
http://www.wildcoast.net/mznews/archives/000037.html
The Argos-linked Telonics ST-10 or ST-18 position
transmitters.
Wildlife Computer Argos-linked satellite transmitter
with dive recorder capabilities (SDR-T10).
Personnel of the National Marine Fisheries Service’s
Observer Program.
Genetic analyses.
The Sea-viewing Wide Fieldof- view Sensor (SeaWiFS) .
TOPEX/Poseidon
Satellite telemetry from 26 Caretta caretta and 10 Lepidochelys
olivacea captured and released from pelagic longline fishing gear
provided information on the turtles’ position and movement in the
central North Pacific.
3 loggerheads and 2 olive ridleys to be sexually mature; however,
all the other turtles were likely immature.
The time period from January 1997 to August 2001 for a total of 2470
transmission days.
The Argos-linked Telonics ST-10 or ST-18 position transmitters
were attached to 32 turtles .
http://www2.dmu.dk/1_Viden/2_Publikationer/3_F
agrapporter/rapporter/FR484_1-25.PDF
http://tw.search.yahoo.com/language/translatedPage?tt=url&text=http%3a//www.mrf-asia.org/projects_view.cfm%3fTHE_ID=14&lp=en_zt&.intl=tw&fr=notfound_dic
2 loggerhead and 2 olive ridley turtles were instrumented with a
Wildlife Computer Argos-linked satellite transmitter with dive
recorder capabilities (SDR-T10).
This transmitter provides 3 frequency distributions for each of four
6-h (21:00~03:00, 03:00~09:00, 09:00~15:00, and 15:00~21:00 ) time periods.
1. time spent in each of 14 (1, 3, 5,
10, 15, 25, 35, 50, 60, 75, 100, 125,
150, 150+.)preset depth bins.
2. duration of each dive.
3. the depth for each dive.
http://www2.dmu.dk/1_Viden/2_Pu
blikationer/3_Fagrapporter/rapport
er/FR484_1-25.PDF
The National Marine Fisheries Service’s Observer Program attached
transmitters to the turtles onboard commercial fishing vessels.
26 loggerheads were determined by genetic analysis to have come
from Japanese nesting beaches.
9 olive ridleys showed that 6 came from eastern Pacific nesting
beaches and 3 came from the western Pacific.
The SST data were multichannel SST (MCSST) with
weekly temporal resolution and
one-tenth of one degree of
longitude and latitude spatial
resolution.
wikipedia
Sea-viewing Wide Fieldof- view Sensor
(SeaWiFS) :
http://visibleearth.nasa.gov/view_rec.php?id=5
To estimate chlorophyll a concentration and
provide useful data on ocean color to the Earth
science community .
The data resolution was monthly, September
1997~August 2001, at 0.088 latitude and
longitude.
Launched in 1992, to map ocean
surface topography and monitor
water current and SSH.
http://topex-www.jpl.nasa.gov/mission/topex.html
TOPEX/Poseidon :
Migration tracking lines.
Dive depth.
Distribution with geostrophic currents.
Forage.
http://www.seawear.com/jewelry/turtles.html
Track lines of 26 loggerhead & 10 olive ridley :
solid dots mark the start of each track line
greatest distance
Loggerheads : occupying the northern portion 22°N~41°N of the
Subtropical Gyre (28°N) and the Transition Zone .
Olive ridleys : a broader latitude range than for loggerheads,
primarily from 6°N–31°N in the Subtropical Gyre
and the equatorial regional.
0
45 N
0
30 N
0
15 N
0
135 E
0
150 E
0
165 E
0
0
1800E
165 W
赤
150 W
0
135 W
道
Hawaii-based longline fishery 6°N~41°N;130°W~150°E
The spatial distribution of all track lines for the 36 turtles
0
120 W
The greatest distance traveled for each species group
The loggerhead (60.0 cm SCL) traveled over 9000 km in 458 days.
The olive ridley (52.0 cm SCL) traveled 7282 km in 193 days.
Both of them more than twice the distance traveled by any other .
The physical and biological environmental data used to describe
the environment at and around the migrating loggerheads and
olive ridleys are sea surface temperature (SST),
surface chlorophyll a concentration, and geostrophic current :
Kuroshio Extension Current (KEC): south-eastward flowing
North Equatorial Current (NEC) : westward -flowing.
Equatorial Counter Current (ECC) : eastward -flowing.
http://news.zbedu.net/dili/uploadfile/200591313431235.jpg
SST-frequency
distribution
Olive ridleys : occupied 23°C~28°C during all quarters.
Loggerheads : occupied cooler water and broader : 15°C~25°C.
Many of the turtles remained in very narrow SST ranges during their
entire transmission time.
The TZCF represents the boundary between the stratified low surface
chlorophyll (<0.15 mg m-3) waters of the Subtropical Gyre and the
high surface chlorophyll (>0.3 mg m-3) vertically mixed waters in the
Transition Zone and Subarctic Gyre.
TZCF (transition zone chlorophyll front) was an important forage
habitat (including squid, albacore, and pomfret) representing a
convergence zone where cool plankton-rich water from the north
converges and sinks beneath warmer nutrient-poor water to the
south , resulting in a gradient in SSH that generates a weak
eastward flowing geostrophic current which the loggerheads swim
against as they travel westward, and loggerheads occupy the TZCF
throughout the year.
Time-at-depth
Loggerheads : relatively shallow dives and they spent 40% of
their time at the surface and about 90% of their
time at depths < 40 m.
Olive ridleys : they spent only about 20% of their time at the
surface and about 40% of their time > 40 m.
Temperature
depth &
chlorophyll
depth
Olive ridley : the chlorophyll maximum was deeper than 100 m,
although it shoaled to the surface at 10°N latitude at
the northern edge of the NEC.
Loggerhead : with the subsurface chlorophyll maximum above 100m
and reaching the surface at 33°N when it became
the TZCF.
KEC (35°C) and
sea surface
height
estimated
together with
the track
line and
positions (dots)
of the
loggerhead
turtle for 10
day periods in
2.12~22;
3.13~23;
4.12~22.
KEC may be an important habitat (ex: juvenile bluefin from
December through June.) because the strong meanders from the
KEC entrain deep cool, productive waters rich in nutrients and
possibly a biological community from the northern side of the
KEC into cyclonic eddies.
The KEC is shown as strong eastward flowing current along 35°N,
and the turtle track line shows the turtle’s westward (24/26)
movement was often assisted by the westward flow on the north
side along 33°N of the 2 cyclonic eddies at 165°E and 180°E are
regions of enhanced surface chlorophyll .
http://61.236.182.2/webmedia/html/movie_121.shtml
Geostrophic
currents
along the
NEC with
olive ridley
track line
As olive ridley headed westward in the NEC, it traveled at about 71
cm s-1 and as the NEC traveled at only 32 cm s-1, the turtle
appeared to be actively swimming and not just drifting as it rode
the NEC, most likely to continually find needed prey.
This olive ridley traveled eastward along the eastward-flowing ECC
in September and then north and westward during October and
November in the NEC .
http://www.montereybay.com/creagrus/sea_turtles.html
Geostrophic
currents
estimated
along the
NEC & ECC
with olive
ridley track
line
Janthina sp
http://reproduce.nmmba.gov.tw/main04_1_4.htm
Vellela vellela
Their most common prey from 53
loggerheads are floating organisms and
organisms riding on floating objects.
These include the predatory gastropod
Janthina sp.(紫螺) , and its prey Vellela
vellela (By-the-wind sailor), gooseneck
barnacles, Lepas sp., and the pelagic crab
Planes cyaneus which ride on logs, floats.
The only common diet item not found
exclusively at the surface was the
heteropod Carinaria cithara .
http://tw.search.yahoo.com/language/translatedPage?tt=url&text=http%3a//www.ncrcn.org/me/projects/tidepool/gooseneckbarnacle/gooseneckbarnacle.html&lp=en_zt&.intl=tw&fr=notfound_dic
Planes cyaneus
http://www2s.biglobe.ne.jp/~palaemon/grapsida.htm
gooseneck barnacles
http://research.kahaku.go.jp/zoology/zoopl-new/s-pl/s-moll/s-moll.htm
http://tw.search.yahoo.com/language/translatedPage?tt=url&text=http%3a//earthguide.ucsd.edu/earthguide/imagelibrary/velellavelella.html&lp=en_zt&.intl=tw&fr=notfound_dic
Carinaria cithara
An analysis of stomach contents from 8 olive ridleys caught in the
Hawaii-based longline fishery indicates that while they do forage
on some surface associated organisms including Janthina sp. and
cowfish (Lactoria diaphana), their most common prey are
pyrosomes (Pyrosoma atlantica) and salps (Salpidea), which are
found subsurface.
http://www.julianrocks.net/portraits/cowfish.htm
Photograph by Dick Williams
Lactoria diaphana
salps (Salpidea)
http://jellieszone.com/pyrosoma.htm
Pyrosoma atlantica
Habitats of loggerheads and olive ridleys.
Conservation.
Photo: Carlos Drews/World Wildlife Foundation/AP
Loggerhead and olive ridley turtles occupy habitats with different
physical and biological characteristics and as a result utilize
different types of forage and migration habitat.
Loggerhead occupy the northern edge of the Subtropical Gyre
and the Transition Zone, waters characterized by a shallow
thermocline, strong thermal and chlorophyll gradients, and
surface convergent fronts.
As a result they tend to have a relatively shallow dive depth
distribution, spend considerable time at the surface, (however,
olive ridley is tatolly opposite from loggerhead.) and associate
with eddies and fronts including the TZCF and the southern
edge of the KEC.
Olive ridleys inhabit two different oceanic regions.Most of them
tracked remained in the center of the Subtropical Gyre.
In addition to inhabiting stratified Subtropical Gyre waters,
three olive ridleys occupied a different habitat consisting of major
oceanic currents.
One traveled along the southern edge of the KEC at the north
boundary of the Subtropical Gyre
while two traveled in the equatorial region south of the Subtropical
Gyre using the NEC and ECC.
While many turtles caught in the longline fishery were hooked in
the mouth, externally hooked, or entangled, the observer was able
to remove the hook before releasing the animal.
However in both these turtles the hooks were deeply ingested, so
they were released without removal of the hooks.
http://www.seashepherd.nl/news/media_040501_1.html
http://www.commondreams.org/headlines02/images/0521-04.jpg
The reduction of incidental catches of sea turtles in pelagic
fisheries is an important management goal.
All the incidental catches of loggerheads occurred on shallow sets
<100 m depth
1. In March 2001, prohibited shallow longline sets in the Hawaii
fishery.
2. The findings that the TZCF, the southern edge of the KEC, the
NEC and ECC represent important forage habitat for
loggerheads and olive ridley suggest that reducing fishing
effort in these areas will also reduce the incidental take of these
turtles.
Finally, our analyses should prove useful
in identifying oceanic marine-protected
areas designed to protect pelagic animals
in their spawning and foraging habitats .
Legal notice posted by nest at Vero Beach, Florida
http://img.groundspeak.com/track/log/89112_200.jpg
http://www.turtles.org/why.htm
Report is end
but conservation still continued