true

ISRA FACTSHEETS

WESTERN INDIAN OCEAN REGION

ISRA FACTSHEETS

WESTERN INDIAN OCEAN REGION

Fesdu Falhu ISRA

41/125

Fesdu Falhu ISRA

Fesdu Falhu

Summary

Fesdu Falhu is an enclosed lagoon located in North Ari Atoll, Maldives. The lagoon measures ~2.8 km in length and ~1.4 km in width. The inner basin reaches a maximum depth of 20 m with a substrate of fine sands and scattered coral blocks. The geomorphology of this shallow lagoon coupled with the tidal movements acts as a zooplankton trap. Within the area there are: threatened species and feeding areas (Reef Manta Ray Mobula alfredi).

Fesdu Falhu

Fesdu Falhu

DESCRIPTION OF HABITAT

Fesdu Falhu is an enclosed lagoon located in North Ari Atoll, Maldives. The inner basin area is 20 m deep and is characterised by sandy substrates with several scattered coral blocks. In the north of the lagoon there is a section of reef which does not rise to the surface.

The geomorphology of the shallow lagoon coupled with the tidal movements and Langmuir Circulation acts as a zooplankton trap, especially during the southwest monsoon (May–November) (Hedley et al. 2018; Moloney et al. 2019; Harris et al. 2020; Harris & Stevens 2021).

The tides in the Maldives are characterised by a semidiurnal microtidal regime with a tidal range of ~1 m (Caldwell et al. 2015; Rasheed et al. 2021). Combined tidal and wind-driven currents can exceed speeds of 2 m/s, and be very variable in speed and direction, especially though the channels between atolls, atoll rims, and channel gaps in the atoll rims (Ciarapica & Passeri 1993; Kuiter & Godfrey 2019; Rasheed et al. 2021).

This Important Shark and Ray Area is benthopelagic and is delineated from inshore and surface waters (0 m) to 20 m based on the bathymetry of the area.

CRITERION A

VULNERABILITY

The one Qualifying Species occurring in the area is considered threatened with extinction according to the IUCN Red List of Threatened SpeciesTM. The Reef Manta Ray is assessed as Vulnerable (Marshall et al. 2022).

CRITERION C

SUB-CRITERION C2 – FEEDING AREAS

Fesdu Falhu is an important feeding area for one ray species.

This is one of the main feeding areas for juvenile Reef Manta Rays in North Ari Atoll. Data from citizen science submissions and Underwater Visual Census (UVC) surveys utilising photo-identification during 2011–2022 recorded 580 sightings of feeding Reef Manta Rays across 243 surveys. Feeding has been recorded in 234 of these surveys (96%), with aggregations of 2–6 animals on average (maximum = 11). Ninety-five percent (n = 54) of the individuals identified in Fesdu Falhu are recorded during feeding events. Seventy percent (n = 38) of these feeding manta rays are young-of-the-year (YOY) or juvenile Reef Manta Rays that find an abundance of prey in this sheltered lagoon (IDtheManta unpubl. data. 2022). The feeding aggregations are mostly observed just after sunset or at night, regularly and predictably. Individuals in the aggregations are observed actively feeding individually or in feeding chains. Feeding is observed mostly year-round, with slight peaks throughout the northeast monsoon (IDtheManta unpubl. data. 2022). Of the YOY and juveniles recorded in Fesdu Falhu (n = 40), 35% of the animals have been recorded at Fesdu Falhu over consecutive years, confirming that this area is used repeatedly across years.

Fesdu Falhu

SUBMIT A REQUEST

ISRA SPATIAL LAYER REQUEST

To make a request to download the ISRA Layer in either a GIS compatible Shapefile (.shp) or Google Earth compatible Keyhole Markup Language Zipped file (.kmz) please complete the following form. We will review your request and send the download details to you. We will endeavor to send you the requested files as soon as we can. However, please note that this is not an automated process, and before requests are responded to, they undergo internal review and authorization. As such, requests normally take 5–10 working days to process.

Should you have questions about the data or process, please do not hesitate to contact us.

    * indicates required

    Industry or sector (*)

    Under the terms and conditions of our User License Agreement , full and appropriate acknowledgement is required in any materials and publications derived from the data (and copies should be sent to the IUCN SSC Shark Specialist Group through the contact form). For any publications making substantial use of the data, the ISRA welcomes the opportunity for co-authorship, collaboration, and to comment prior to publication.


    Furthermore, we need to know whether you are a commercial or non-commercial user. Non-commercial includes scientific research, education or conservation. Commercial is defined as follows: any use by, on behalf of, or to inform or assist the activities of a commercial entity (that operates ‘for profit’) or use by a non-profit for the purposes of revenue generation

    Type of use(*):

    Please specify which layer (ex. all layers, layers within a specific Region, layers within a Jurisdiction or a single ISRA): Purpose (*):

    Please provide a description of how you intend to use the ISRA GIS Dataset. The more details you provide, the faster we can respond to your request. We may require further clarification prior to providing access. (min. 100 characters – max 1,000 characters)



    File format request (*)

    By providing your personal data, you consent to its processing as described below. The IUCN SSC Shark Specialist Group will use the information you provide on this form to send the documents you requested. You can change your mind at any time by writing to the ISRA Data Coordinator www.sharkrayareas.org/contact. All personal details provided will be treated with respect. For any information you can visit our Privacy Policy.
    Please read the User License Agreement and ISRA Layer Metadata Description

    This form uses Google reCaptcha to reduce spam. Privacy - Terms