dugongs in palau - C3

Spatial distribution
A total of 27 individuals were counted during the course of the 2003 survey, seven of which were calves.
As in previous years, the highest concentration of dugongs was found in the Malakal Harbor area. Most
sightings in the northern waters of Babeldaob occurred in the western lagoon, close to the states of
Ngatpang and Ngardmau. Only one individual was see n on the eastern side of Babe ldaob. In all previous
aerial surveys, with the exception of 1983, the Malakal Harbor area (see segment s I, II and VII on Figure
5) has been identified as an important habitat for dugongs, with the greatest concentrations of animals
being observed here. Typically, 35-60% of the total animals recorded were seen in this area.
The earliest surveys (1977, 1978 and 1983) were not compared in Table 3 because of differences in
aircraft, longer flight tim es (up to 2-3 times the length of later surveys) and/or number of times each
segment was surveyed (between 1 and 9 times in earlier survey compared to 1-3 times in later surveys).
Only 7.7 % of dugongs observed in the 2003 flight wer e in shallow water (where the bottom was visible)
and this is consistent with Marsh’s observations in the 1991 survey, when all but 8 % of dugongs were
seen in deep water (Marsh et al., 1995).
Most dugongs are found in segments I – II, (Malakal Harbor and north-east of Ngel Channel towards
Airai) and V-VI (Ngardmau Bay and the western lagoon). No dugongs have been seen north of
Ngerchelong except for a mother and calf pair sighted in Kossol Lagoon in 1998. Few dugongs have
been seen south of the Malakal Harbor area, with no sightings recorded south of Mecherchar in the waters
of Peleliu or Angaur. However, in 1978 and 1983, six individuals were seen in the southern sections of
VIII, IX and X. These observations may have been due to increased flight times (up to twice as long).
The aerial sightings for these three survey years are displayed in Figure 6.
No. of Dugongs
Adults—Calves
% of Total Dugongs Counted
Segment 1991 1998 2003 1991 1998 2003
I 3—1 3—1 3—1 15.4 12.1 14.8
II 1—1 13—2 9—3 7.7 45.5 44.4
III 2—0 0—0 1—0 7.7 0 3.7
IV 1—0 0—0 1—1 3.8 0 7.4
V 4—0 2—2 3—1 15.4 12.1 14.8
VI 10—2 5—0 1—0 46.2 15.2 3.7
VII 1—0 1—0 0—0 3.8 3 0
VIII 0—0 1—1 1—1 0 6.1 7.4
IX 0—0 0—0 0—0 0 0 0
X 0—0 0—0 1—0 0 0 3.8
XI 0—0 1—1 0—0 0 6.1 0
XII 0—0 0—0 0—0 0 0 0
Sub-Totals 22—4 26—7 20—7
TOTAL 26 33 27
Table 3: Relative distribution of dugongs in aerial survey segments (Figure 5). Segments
which >10% of the total number of dugongs were sighted have been highlighted.
in
9