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Manta Fishery: Initial Investigations

By Sarah Lewis, 14th November 2011

A major aim of the Indonesian Manta Project is to assess the scale and impact of manta ray fishing in Indonesian waters. Over the last few months we have been conducting initial investigations to determine the sites where manta rays are being landed and the areas where manta fishing is occurring.
Fishing pressure is a major threat in Indonesian waters and mantas are caught as by-catch in local gillnet fisheries for tuna and in directed fisheries that are targeting mantas primarily for their gill rakers to be used in Chinese medicine.
Through literature reviews, visits to fish markets and interviews with dive operators, local fishermen, researchers, and NGO’s, an alarming number of manta landing and fishing sites have been reported throughout Indonesia and it is likely that more exist that we haven’t discovered yet.
Manta population declines have been reported near Sangalaki Island off the East Kalimantan coast, and although the reason for the declines has not been determined, reported manta ray landings at a East Kalimantan fish market suggest that fishing pressure could be a potential cause. It may also be possible that, rather than the population declining, environmental changes (anthropogenic or natural) may be affecting this population’s visitation patterns at known aggregation sites. Using photo-ID techniques and with the help of local dive operators we have set up a monitoring program in Sangalaki and the surrounding area, which we hope will help shed light on this population of manta rays and determine the cause of any possible declines or change in site visitation patterns.

If you or anyone you know has been to Indonesia and taken photos of manta rays in Sangalaki (or any other part of the country) or have any information regarding manta fishing we would love to hear from you, any information is greatly appreciated … can send me email at

In depth fish market surveys are set to begin soon……so stay tuned as more on this to come.

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