Manta Project Fiji Impact Report 2023

The Population
Sex Demographics
Male
Female
Percentage
Unknown
The Kadavu sub-population is split almost
50-50 between males and females.
There is a slight majority of males with
53% of manta rays being male and 46%
being female and 1% being of unknown
sex.
183 Manta Rays
Melanistic
Chevron
Percentage
color morph demographics
The Kadavu sub-population displays
one of the lowest melanism proportions
in Fiji with only 34% of manta
rays being melanistic and 66% being
chevron.
North Kadavu
Region
Yaukuve Island
Group
Vuro Island
Key Partner
Kokomo Private
Island Fiji
Manta Project Fiji and Kokomo Private Island Fiji started
collaborating in 2019 to better understand manta ray
population dynamics, demographics and movement
ecology in the region.
Two main research sites exist in the region, Vuro Island,
which is a shallow cleaning habitat for manta rays and the
Yaukuve Island Group, a primarily foraging habitat for
manta rays.
Project Overview
Reef Manta Ray
(Mobula alfredi)
Kadavu is the third largest island in Fiji and is in the southern region,
approximately 75km from Suva. Kadavu and nearby islands are surrounded by
the Great Astrolabe Barrier Reef system which extends over 100km along the
eastern side and encloses the entire northern region within a lagoon. The
primary survey area encompasses the whole north Kadavu region from Ono to
Solo Reef.
Kadavu attracts a much smaller number of tourists when compared to the
Yasawa Islands, most likely due to its harder to reach location. Kadavu typically
attracts less than >4% of Fiji’s visitors. However, due to the luxury status of
multiple resorts, the region sits much closer to the revenue power of the
Yasawa Islands.
The primary survey area encompasses multiple islands and a large reef system
where manta rays can be sighted year round, however, sightings
typically peak between May and November every year. Both cleaning and
foraging habitats are surveyed in this region.
250
200
150
100
50
0
66
Annual Survey
Days
203
227 233 231
2019 2020 2021 2022 2023
100
90
80
70
60
50
40
30
20
10
0
55%
90% 89%
2023
2022
2021
2020
Percentage of survey
days manta rays were
sighted
120 sightings were of
foraging behaviour
82%
94%
2019 2020 2021 2022 2023
Sighting Variation
642 sightings were of
cleaning beahviour
802
Sightings
542
Sightings
1041
Sightings
1027
Sightings
2019
514
Sightings
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
2023 in review
28 sightings were
courting behaviour
Surveys were conducted on 231 days between April - November
Manta rays were sighted on 94% of survey days
80 drone flights were conducted
804 manta ray sightings recorded
131 different manta rays were recorded
Manta sightings peak
between April - November
every year. During 2023
manta sightings peaked
during June and July.
We recorded 802 manta
sightings during 2023,
significantly more than
both 2019 and 2022,
however this is still 200
sightings less than both
2021 and 2020
428 (53%) sightings were of female manta rays and 373 (47%) of
male manta rays
There were an average of 5 snorkelers in the water when manta rays
were present