Author: Sudaryanto, Bira Project’s Jr Marine Biolgist, Indo Ocean Foundation
The Scalloped Hammerhead Shark (Sphyrna lewini) is listed as Endangered on the IUCN Red List due to steep global population declines (IUCN, 2021). In Indonesia, Sphyrna lewini is subject to multiple pressures, including targeted and incidental catch, degradation of coral reef habitats, and lack of consistent monitoring data (White et al., 2006; Fahmi & Dharmadi, 2015). Despite being included in Indonesia’s national list of protected species since 2018, current knowledge of its distribution and behavior in many parts of the country remains limited. South Sulawesi, particularly the Bira region, is not widely documented as part of Sphyrna lewini core habitat, and confirmed sightings in this area are small. As part of ongoing elasmobranch monitoring efforts in the region, a BRUV (Baited Remote Underwater Video) unit was deployed to assess species presence and relative abundance of large predatory fishes.
On September 2024, a BRUV unit was deployed at a depth of 27 meters along a sloping reef wall off the northern coast of Kambing Island, near Bira. The area is characterized by moderate to strong currents, high structural complexity, and a history of mesopredator activity. The unit was deployed for a total of 60 minutes and used a standardized bait quantity composed of crushed mackerels in a perforated canister to attract carnivorous species. At minute 60:04 of the recording, a single Sphyrna lewini entered the frame three times. The individual exhibited exploratory swimming behavior, passing slowly and bit the bait pole before exiting the field of view after approximately 12 seconds and swimming in the distance twice. Visual assessment indicates a healthy, subadult specimen with no apparent injuries or tagging marks.
This observation constitutes one of the few recent records of Sphyrna lewini in the South Sulawesi region, and to our knowledge, the first BRUV documented presence near Bira. The result is significant for several reasons:
- It provides direct, timestamped video evidence of Sphyrna lewini in an area with limited existing data
- It confirms the utility of BRUV methods in detecting elusive and highly mobile species in reef associated systems (Langlois et al., 2015).
- It suggests that the Bira, Kambing Island area may represent either a transient pathway or a foraging ground within the broader migratory range of Sphyrna lewini.
As BRUV deployments continue across seasonal and spatial gradients in South Sulawesi, the accumulation of such data may support larger-scale ecological models, refine species distribution maps, and contribute to management recommendations for mobile marine predators in Indonesian waters. The BRUV based detection of Sphyrna lewini in Bira adds to the growing dataset on elasmobranch biodiversity in the region. While limited in scope, such observations are critical for building a baseline understanding of shark presence and behavior in lesser surveyed parts of Indonesia. Long term, standardized monitoring will be necessary to assess patterns of habitat use and to inform conservation efforts for this and other threatened species.
References :
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Fahmi, & Dharmadi. (2015). Indonesian Elasmobranch Fisheries: Recent Status and Policy Management. Indonesian Fisheries Research Journal, 21(2), 53–64.
IUCN. (2021). Sphyrna lewini. The IUCN Red List of Threatened Species 2021: e.T39385A2918526. https://www.iucnredlist.org/species/39385/2918526
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