Protection and healthy coral cover help conserve largest herbivorous fish

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Posted in: Press Release

Bangalore, 12 March 2019: Marine protected areas and live coral and algal cover help in
conservation of the largest herbivorous and corallivorous fish (that feed on live coral), the bumphead
parrotfish (Bolbometopon muricatum), according to a new paper published in Oryx journal. The
study was conducted by Vardhan Patankar, marine biologist with WCS-India and NCBS, Tanmay
Wagh from Dakshin Foundation and Aniruddha Marathe from Atree.

This fish is a highly prized fishery resource worldwide and has experienced population declines
throughout its geographical range. There is limited knowledge of the distribution and abundance and
threats to this fish in Indian waters. It is categorized as Vulnerable on the IUCN Red List.
To assess the species’ distribution and conservation status, the team conducted underwater surveys
across 75 sites in 51 islands and interviewed 99 fishers across the Andaman and Nicobar
archipelago. A total of 59 individuals of bumphead parrotfish was recorded across nine sites from
the northernmost island in the Andamans (Landfall Island) to the southernmost island in the
Nicobars (Great Nicobar Island).

With one individual having the capacity to consume up to 5 tonnes of structural reef carbonate per
year, the parrotfish have important functional roles in structuring coral reef ecosystems. (They
promote coral growth and recruitment by balancing coral erosion and calcification, preventing
macroalgal growth and maintaining sediment flow in the reef system.) Their conservation is a key
priority for ecosystem managers.

“A large body size, aggregating behaviour and limited activity at night make B. muricatum an easy
target for spear- fishers. Combined with slow growth and low replacement rates, this has resulted in
population declines across the Indo-Pacific and Red Sea regions,” says first author Vardhan.
In India B. muricatum occurs from the Gulf of Mannar in Tamil Nadu state to the Lakshadweep
archipelago and the Andaman and Nicobar Islands. Little is known about the species’ distribution
and conservation status around the Andaman and Nicobar Islands. In the recent past the islands have been affected by a series of coral bleaching events and the tsunami of 2004 which may have disturbed the species’ habitat. It was in this context that the present study sought to look into the abundance, distribution and conservation status of the fish in the region.

Marine protected areas in which fishing and other activities are restricted aid the conservation of fish
stocks and in the Andaman and Nicobar Islands the existing protected areas may be vital for the
protection of B. muricatum and other fishes, the study found. Evidence of low abundance of B.
muricatum on ocean reefs surrounded by deep waters, and traits such as limited dispersal and
gregariousness, could also have influenced the distribution and abundance of this fish.

Among current potential threats to B. muricatum in the Andaman and Nicobar Islands are incidental
catch by fishers and degradation of coral reef habitats. Although the present protected areas are
supporting higher abundances of B. muricatum, fishing and benthic degradation could potentially
result in future declines. Most fishers in the Nicobars (91%), all fishers in Middle Andaman, and 8%
of fishers in South Andaman had hunted the fish in their lifetime, using hand-held wooden spears or
harpoons, mostly in daylight. All fishers who had caught the fish in their lifetime reported that the
catch was opportunistic rather than targeted.

Long-term population studies of these species coupled with Red list assessments and inclusion in the
Indian Wildlife (Protection) Act, which bans night fishing; could help avoid population declines. B.
muricatum can be used as a flagship species for educational campaigns to focus on the importance of
conserving fish populations and instilling the value corals reefs have on the island.

Contact: Vardhan Patankar (

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