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ISRA FACTSHEETS

WESTERN INDIAN OCEAN REGION

ISRA FACTSHEETS

WESTERN INDIAN OCEAN REGION

Maroshi Thila ISRA

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Maroshi Thila ISRA

Maroshi Thila

Summary

Maroshi Thila is located in central-western Shaviyani Atoll in the northern Maldives. This area is an underwater pinnacle reef rising from the seafloor at 40 m to the top at 14 m deep. The area is characterised by a shallow reef top, steep reef slopes, and sand and rubble substrates. Within this area there are: threatened species and undefined aggregations (Bottlenose Wedgefish Rhynchobatus australiae).

Maroshi Thila

Maroshi Thila

DESCRIPTION OF HABITAT

Maroshi Thila is located in the northern Maldives archipelago which sits centrally upon the Chagos- Laccadive Ridge (Stevens & Froman 2019). This area is a submerged shallow reef located in central-western Shaviyani Atoll (politically designated name), also known as north Thiladhunmathi Atoll. Thila is a local name that refers to underwater pinnacle reefs located within the atoll lagoon where the top is completely submerged even during low tide (Godfrey 2018). In this area, the top of this reef starts from 14 m and the reef edge drops to 40 m. The seafloor is covered in sand and rubble.

This Important Shark and Ray Area is benthic and is delineated from surface and inshore waters (0 m) to 40 m based on the depth range of Qualifying Species in this area and the bathymetry of the area.

CRITERION A

VULNERABILITY

The one Qualifying Species within the area is considered threatened with extinction according to the IUCN Red List of Threatened SpeciesTM. The Bottlenose Wedgefish is assessed as Critically Endangered (Kyne et al. 2019).

CRITERION C

SUB-CRITERION C5 – UNDEFINED AGGREGATIONS

Maroshi Thila is an important area for undefined aggregations of one ray species. The information available comes from personal observations and communications from recreational divers who dive regularly in this area. Although, limited surveys have been done in this area, aggregations have been recorded.

Bottlenose Wedgefish have been observed regularly and year-round between 2010 and 2023 by divers. This area is reportedly the best place in the Maldives to observe Bottlenose Wedgefish, with a high chance of seeing them on a dive (50–90% chance based on the start location of the dive; F Gansi pers. comm. 2023). Animals are usually resting on the sandy and rubbly seabed at 25–40 m depth (G Stevens pers. obs. 2023). Aggregations of up to seven individuals have been reported in the area; however, usually only 1–3 large females are usually present at the site (G Stevens pers. obs. 2023; N Froman pers. comm. 2023; F Gansi pers. comm. 2023). Courtship behaviour has been reported twice in which six smaller males followed or surrounded a female (N Froman pers. comm. 2023). Males have only been seen during courtship events (G Stevens pers. obs. 2023; N Froman pers. comm. 2023). It is hypothesised that males remain at deeper depths in the atoll lagoons away from the reefs and move to shallower areas seasonally to mate probably between August and February when these courtship events have been reported in this area and in other locations in the Maldives (G Stevens pers. obs. 2023; N Froman pers. comm. 2023). Further records are needed to confirm that these courtship events are regular and predictable and determine if this area is important for reproductive and/or resting purposes.

Maroshi Thila

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