| Jan 13, 2020
The past three months have been an exciting time for the Island Conservation Expedition. We have continued with our annual Aldabra giant tortoise census in order to locate as many free ranging animals as possible. Our target is to find 90% of known individuals which we have successfully completed. In addition, we have also had 10 adult tortoises donated to us from the neighbouring island of Praslin as well as 10 tortoise juveniles which have been added to our hatchling nursery. This brings our tortoise total up to 165.
Shortly after the tortoise census concluded Hawksbill turtle nesting season and Lemon shark pupping season began. This is always the busiest time of year on Curieuse, with daily monitoring of the main turtle nesting beaches. So far this season we have had 98 turtle nests spread out over five beaches across the island. Additionally, we have ID tagged 21 nesting female individuals .
The Lemon shark study has been extremely interesting during the peak season too. Since pupping season began on 15th October we have caught 140 individuals with our highest number of sharks caught in one survey being 23. We have primarily been catching Lemon sharks however similarly to the previous quarter we have also been catching a number of other shark species, with some previously not known from the study area. Several pups of Blacktip reef shark (Carcharhinus melanopterus) and Oceanic blacktip (Carcharhinus limbatus) have been captured and tagged, and one Scalloped hammerhead (Sphyrna lewini) pup was also caught.
Another exciting development has been the continuation of the Lemon shark tracking study. With generous funding from the Seychelles Climate Conservation Adaptation Trust (SeyCCAT) we have been able to purchase 12 acoustic receivers and 25 transmitters. We have done further extensive testing to determine receiver detection range prior to the arrival of this year’s pups, at which point we began surgically implanting transmitters to follow the pups. We have successfully detected shark acoustics surrounding Curieuse which is helping us to assess the effectiveness of the national park in their protection.as well as vastly increasing our knowledge of their movements.
Another recent addition to the range of projects with Curieuse is an experimental eradication of invasive rats in an area of coastal forest near the base. Rats were accidentally introduced to Curieuse by the original colonists of the Seychelles, and since then they have decimated the populations of many native species. Most notably there are no nesting seabird colonies on Curieuse while close by rat free islands have extensive colonies, and many other endemic species such as lizards have also been negatively impacted. The project has now humanely eradicated roughly 682 Black rats (Rattus rattus) from a two hectare area of sensitive coastal forest habitat, and we are now beginning to see encouraging signs of ecosystem recovery.
The Baited Remote Underwater Video (BRUV) study has captured 36 hours of video footage of carnivorous and scavenging fish species in shallow and deep habitats off the poorly studied north coast of Curieuse. Review of the footage has just been completed, and data analysis will begin shortly, however one notable new discovery this season was a Snaggletooth shark (Hemipristis elongata). We await the results of the analysis to see the comparison in these fish detections with previous seasons.
The annual mangrove survey was also conducted in August, with eight permanent 10m x 10m quadrats being surveyed to assess the trends in mangrove species abundance, diversity and recruitment. R. mucronata, B. Gymnorrhiza and A. Marina are still the most populous type of mangrove on the island and all three are thriving. The data collected thus far has indicated that it is important to also establish permanent quadrats throughout the forest in order to represent all mangrove species present and provide sufficient insight into the changes occurring throughout the entire forest. Continued monitoring is required in order to assess whether the seaward edge of the forest will continue to degrade or whether a natural state of equilibrium has been reached.
We'd like to thank you all for your generous donotions and continuious support. Looking forward to a great year ahead!
Seychelles Curieuse Island Conservation