Conservation through Research, Awareness and Education

UK Registered Charity Number: 1145387

Juvenile Manta birostris at a Sri Lankan market.


Project Goals:

To investigate Sri Lanka’s and India’s manta and mobula fishery and identify key feeding, breeding and nursery grounds. Help establish and implement necessary conservation regulations and management plans together with local communities and organizations. Raise awareness of these species and the threats they face within this region and globally.

Why this is important:

High fishing pressure due to increased demand for mobulid ray gills results in a large number of manta and mobula being landed on a daily basis at Sri Lankan and Indian fish markets. Decreasing catches of the more desired catch species like sharks, tunas and billfishes is also adding to the problem as the fishermen begin to target, with increasing regularity, these previously economically unviable rays. The extremely low fecundity rates, slow growth and late maturity of these species make them even more susceptible to over-fishing. Identification of key mobulid aggregation sites will further help protect these species and provide a deeper insight into their mysterious lives.

Project Overview:

India, the world’s seventh-largest country by geographical area and second-most populous country has a coastline measuring over 7,500 km and includes the island chains of Andaman, Nicobar and Lakshadweep, where both manta and mobula rays can be seen. Situated just to the south of India and north-east of the Maldives, Sri Lanka is a small island nation which is home to oceanic manta rays as well as a number of other smaller mobulid ray species. Unlike the Maldives, where mantas are protected by an export ban and greatly valued as a charismatic attraction for the dive and snorkel tourism industry, the mantas of Sri Lanka and India are severely threatened by local fisheries and receive no local or national protection at all.

Sri Lanka and India are among the world’s major exporters (along with Indonesia) of dried manta/mobula gills for the Chinese medicinal trade, with many thousands of these animals killed and processed each year. While the targeted fishery for these species are minimal, the numbers caught as by-catch in the tuna gill net fishery is quite staggering. The Manta Trust has partnered with local researchers to collect data on this mobulid ray fishery to determine which species are being most heavily targeted and gain greater insight into the economics of this manta and mobula gill raker trade; from its source in Sri Lanka and India, to the consumer market in SE Asia.

A typical daily scene at Negombo fish market in Sri Lanka.

Data collected from the dead animals at these fish markets not only helps to shed light onto this gill raker trade, but also to answer important life history questions about these poorly studied and understood group of rays. Measurements of disc widths at maturity, sexual demographics of the individuals sampled and recorded pregnancies can all help to answer some of the fundamental life history questions for these species.

Preliminary observations of unusually small oceanic mantas caught using nets and harpoons in near-shore marine habitats suggest that Sri Lanka may be an important nursery ground for oceanic mantas. Currently, there is no solid information on where oceanic mantas breed or give birth and juvenile oceanic mantas are an incredibly rare sight in the wild for researchers and recreational divers alike. The possibility of Sri Lanka serving as a habitat for juvenile oceanic mantas makes protecting the manta populations around the country incredibly important, both for local populations and possibly global populations.

Mobula rays at the Therespuram market in India.

Main Objectives:

  1. Survey Sri Lanka’s and India’s fish markets for manta and mobula landings.
  2. Gain insight into the gill raker trade (local and international).
  3. Identify key feeding, breeding and/or nursery grounds in the Indian Ocean.
  4. Raise local awareness and investigate alternative and sustainable revenue sources through these species (such as the potential for eco-tourism).
  5. Carry out field-trips to other neighbouring countries, to ascertain the extent of the manta and mobula fishery within the region.


  • A preliminary Study of the Mobulid Ray Fishery of Sri Lanka (Stevens – April, 2010). Manta Trust.
  • A Study of Sri Lanka’s Manta & Mobula Ray Fishery (Fernando & Stevens – September, 2011). Manta Trust.
  • A Study of India’s Manta & Mobula Ray Fishery (Fernando – January/February, 2012). Manta Trust.
  • Diminishing Ray of Hope” documentary by Al Jazeera, 101 East.

Partners & Sponsors:

Without the generous support and sponsorship we receive we would not be able to achieve our work in Sri Lanka and India. We are very grateful to these organisations for their support.

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© 2017 Manta Trust