Yasawa Annual Report 2022

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7. Pregnancies & courtshipCourtship has only been recorded in July, August and September at the Manta Channel, indicatingthat these months are considered to be the courting season for mantas in the Yasawa Islands.Courtship sightings peaked in 2013, 2016 and 2021 (2013, n = 32; 2016, n = 39; & 2021, n = 22respectively). In 2022, 12 courtship sightings were recorded (Figure 21).Figure 21 - Dot Plot with the number of annual courtship sightings against the number of pregnant individuals recorded at the Manta Channel,Yasawa Islands, Fiji26
The gestation period of manta rays is a little over one year, with pregnancies becoming visible toresearchers between 4-6 months. In the Yasawa Islands we estimate pupping season to be roughlySeptember and October based on gestation periods. 15 different females have been recordedpregnant at the Manta Channel since 2012, with one female (FJ-MA-0018) having been recordedpregnant 5 times. Pregnancies were recorded to be the highest in 2013 and 2014 with 5 and 6pregnancies respectively (Figure 21). Of the 2 recorded prenancies in 2022, one was the first recordedpregnancy for that particular female (FJ-MA-0016), a female who had been sighted at theManta Channel every year since 2012 when she was a juvenile.Of the 21 mature females that have been recorded at the site, 71 % have been recorded pregnantat least once and 35 % more than once. Of the 27 recorded pregnancies at this site 37 % are fromjust two females, with both being recorded pregnant multiple years in a row.Recent findings (Froman et al., 2023) evoke particular scrutiny to establishing a mantas maturitystatus by using the traditional methods: visual features, size and historical sighting records. Theremay be far more mature females in the Yasawa manta population than what is currently quantifiedbecause we employed traditional techniques to determine the maturity status of the Yasawamantas.8. Sub-Lethal InjuriesOf the 140 individuals identified at the Manta Channel, 23 % (n = 32) have been recorded with atleast one sub-lethal injury, with a total of 58 injuries now documented in the Yasawa Islands. Ofthe 58 injuries, 59 % (n = 34) were of natural origin, 33 % (n = 19) were of anthropogenic origin,and 8 % (n = 5) were of unknown origin (Figure 22).Of the 58 injuries, both males and females have had 29 injuries recorded each, with predator bitestaking up a larger percentage of the injuries in males compared to females with 72 % to 41 % respectively.Males also show more boat strike injuries, however females also display injuries fromfishing gear which the male mantas do not (Figure 23). The larger number of boat strikes and sharkbites seen in males could likely be due to the fact that males are typically more migratory and nomadicthan females in their behaviour, leading to more time spent at the surface and travelling indeeper waters.27
Page 1 and 2: The Yasawa IslandsAnnual Report2022
Page 3 and 4: Executive SummaryThis report presen
Page 5 and 6: Manta Project Fiji (MPF) currently
Page 7 and 8: 1.1. The Yasawa IslandsThe Yasawa I
Page 9 and 10: 3.2. 2020 & 2021The 2020 & 2021 sur
Page 11 and 12: 4.1. Oceanic manta ray sighting tre
Page 13 and 14: Consistent with the increase in sig
Page 15 and 16: During the 2022 season the highest
Page 17 and 18: When looking at the discovery curve
Page 19 and 20: 5.4. New IndividualsDuring the 2022
Page 21 and 22: 6. Residency & MigrationThe populat
Page 23 and 24: Figure 18 - Dot plot showing manta
Page 25: RabiIslandNamena IslandWakayaIsland
Page 29 and 30: 9. Environmental VariablesManta ray
Page 31 and 32: 10. TourismTourism accounts for app
Page 33 and 34: Figure 26 - Bubble plot showing ann
Page 35 and 36: Little is known about other critica
Page 37 and 38: MPF is dedicated to assist local co
Page 39: The report was compiled by :Luke Go

Yasawa Annual Report 2022

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