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Marine Turtle Newsletter 55:12-14, © 1991
Fumihiko Sato and Becky B. Madriasau
Division of Marine Resources, MMDC, P. O. Box 359, Koror PALAU 96940
[N.B. F. Sato is a staff member of the Ogasawara Marine Center, Japan; he was recently dispatched to Palau as a Japan International Cooperation Agency (JICA) expert.]
The hawksbill sea turtle population is declining in Palau. This is based on the personal observation of Becky Madriasau, and has also been reported in the literature based on the observations of older fishermen and local Conservation Officers (Pritchard 1982; Johannes 1986; Groombridge and Luxmoore 1989). As a conservation measure, a hawksbill 'head-starting' project [Project Leader Becky B. Madriasau] has been conducted by the Micronesian Mariculture Demonstration Center (MMDC) since 1982. The project has involved the artificial incubation of eggs collected from natural beaches. The resulting hatchlings are reared for six to 12 months prior to tagging and release. To date, 2364 headstarted turtles have been released; 896 were tagged. Seven individuals have been reported recaptured, turtle # 349 has been recaptured twice (Table 1).
Table 1. Release and recapture records for headstarted hawksbills released from the MMDC, Koror, Palau.
|
Released |
Recaptured |
||||
|
Tag |
Date |
Size |
Date |
Location |
Size |
|
278 |
12 Mar 86 |
17.5s |
03 Jul 87 |
Guam |
34.3c |
|
Unk |
-- |
-- |
26 Sep 88 |
Philippines |
-- |
|
393 |
16 Sep 87 |
16.0 s |
05 Oct 88 |
Philippines |
30.5 c |
|
520 |
12 Apr 88 |
14.1 s |
15 Nov 88 |
Philippines |
-- |
|
349 |
06 Feb 87 |
24.1 s |
02 Apr 90 |
Palau |
36.0 s |
|
242 |
16 Sep 85 |
44.4 s |
08 Jan 91 |
Palau |
56.2 c |
|
702 |
09 Nov 88 |
19.5 s |
24 Jan 91 |
Palau |
33.2 s |
|
349 |
02 Apr 90 |
36.0 s |
28 Jan 91 |
Palau |
41.0 s |
s
straight carapace lengthThere is now a growing local awareness that a new approach is needed to conserve the hawksbill population in Palau. This is because headstarting has not been demonstrated to be a proven management technique to restock sea turtle populations, either here in Palau or elsewhere in the world (e.g., Mortimer 1988; Woody 1990; Woody, this issue). Consequently, in 1991 the Palau project initiated a new approach and that is to accumulate natural biological knowledge, especially on reproduction, as a first step toward designing other conservation measures for Palau's hawksbills. We are also tagging turtles in the wild, capturing them either by the "rodeo" method or using SCUBA divers. To date, the project has found 57 nesting tracks during 22 survey trips by boat. However, 25 nests had already been stolen by poachers. Eggs from four nests were transported to the MMDC to protect them from poachers; an additional four nests were stolen, even though the nesting tracks had been carefully camouflaged, and two nests were washed away by the rough waters of a typhoon. We have observed the hatching of 13 nests in situ, and four by artificial incubation (Table 2).
Table 2. Hawksbill hatching success for eggs incubating naturally on the nesting beach (n=13) and by artificial incubation methods (n=4).
|
Nest No. |
% Hatch Success |
Clutch size |
Date Eggs Found |
|
9001 |
95.8 |
71 |
06 Dec 1990 |
|
9002 |
96.2 |
105 |
12 Dec 1990 |
|
91021 |
59.8 |
127 |
03 Jan 1991 |
|
9106 |
81.1 |
37 |
31 Jan 1991 |
|
9108 |
56.7 |
127 |
15 Feb 1991 |
|
9109 |
84.0 |
119 |
15 Feb 1991 |
|
9110 |
89.4 |
132 |
15 Feb 1991 |
|
9111 |
89.9 |
79 |
15 Feb 1991 |
|
9114 |
90.4 |
146 |
07 Mar 1991 |
|
9115 |
14.7 |
108 |
20 Mar 1991 |
|
9116 |
29.8 |
141 |
20 Mar 1991 |
|
9117 |
72.6 |
135 |
20 Mar 1991 |
|
9127 |
88.5 |
78 |
29 Mar 1991 |
|
91012 |
94.9 |
118 |
03 Jan 1991 |
|
91072 |
84.4 |
122 |
15 Feb 1991 |
|
91122 |
82.8 |
122 |
01 Mar 1991 |
|
91252 |
77.6 |
174 |
22 May 1991 |
1
This nest was replanted on higher ground immediately before hatching because the eggs had been wave-washed2
These four nests were transported to the MMDC to protect them from poachersHatchlings from two transported nests (# 9101, # 9107) are now being reared for exhibit and tagging-release experimentation. The survival of these hatchlings in captivity (to 31 May 1991) was 96.7%. Hatchlings from the remaining two transported nests (# 9112, # 9125) were released immediately after hatching. At present, the MMDC is working with the U. S. Fish and Wildlife Service to bring this project into compliance with the U. S. Endangered Species Act. Further details of the project's activities will be given in our next paper.
Groombridge, B. and R. Luxmoore. 1989. The green turtle and hawksbill (Reptilia: Chelonia): world status, exploitation and trade. UNEP/IUCN/CITES Publ. CITES Secretariat, Lausanne, Switzerland. 601 p.
Johannes, R. E. 1986. A review of information on the subsistence use of green and hawksbill sea turtles on islands under United States jurisdiction in the western Pacific Ocean. National Marine Fish. Serv. Admin. Report. SWR-86-2. U. S. Dept. Commerce. 41 p.
Mortimer, J. A. 1988. Management options for sea turtles: re-evaluating priorities. Florida Defenders of the Environment Bulletin 25.
Pritchard, P. C. H. 1982. Marine turtles of Micronesia, p.263-274. In: Biology and Conservation of Sea Turtles (K. A. Bjorndal, Editor). Smithsonian Inst. Press, Washington D. C.
Woody, J. B. 1990. Is 'headstarting' a reasonable conservation measure? On the surface, yes; in reality, no. Marine Turtle Newsletter 50:8-11.