State of the Planet

News from the Columbia Climate School

Student Work Helps Establish Conservation Act in Palau

Isabel Ender, The Manta Trust and David Prieto, Columbia University
Isabel Ender, The Manta Trust, and David Prieto, Columbia University

Originally from Madrid, exploration has been a driving force in David Prieto’s life. He has lived on five continents during the course of his higher education. Playing with Lego sets as child ingrained a deep curiosity for worlds alien to his own and the dichotomies between nature and mankind.

Prieto was awarded first class honors for his undergraduate dissertation on Frank Biermann’s Earth System Governance theory. Prieto graduated from the M.S. in Sustainability Management program in May 2015. While studying at Columbia University, he was sponsored to attend the 2014 United Nations Climate Change conference in Lima and was also invited to contribute to the Comillas Journal of International Affairs in Spain, where he wrote a review of global energy policy in 2015. As a pro bono consultant for The Manta Trust, Prieto helped establish the first Manta Ray Conservation Act in the Republic of Palau, aiding the creation of the sixth largest marine sanctuary in the world.


On Dec. 28, 2015, Koror State signed into law the “Manta Ray Conservation Act,” with the purpose to restrict boat traffic around German Channel to preserve the manta ray population, and increase tourist experience satisfaction and safety at the site.

The Tenth Koror State Legislature found that the habitat of the manta ray (known locally as ouklemedaol) at the German Channel is threatened by an ever-growing number of tourists wishing to experience these majestic manta rays. In May 2015, Prieto completed a comprehensive study of the manta rays in German Channel. The Legislature found that this study was an important analysis of the great financial benefit that the State of Koror received from the tourism industry for manta rays.

David and Kedei Manta alfredi © David Prieto -Manta Trust, 2015
David Prieto and Kedei Manta alfredi. © David Prieto-Manta Trust, 2015


Over the last decade, ecotourism with marine megafauna has become increasingly popular. In the Republic of Palau, manta ray watching tourism contributes over U.S.$6.8 million annually to the economy. However, unregulated marine tourism interactions can negatively affect the species of interest, tourists’ satisfaction levels and safety, and the sustainability of the tourism industry. Palau’s “German Channel” is a key maritime route, representing the only direct passage from the tourist center in Koror to the southern lagoon dive and snorkel sites, with heavy boat traffic passing through daily; yet it is also the most popular and only predictable manta ray watching site in Palau. With tourism growing more than threefold (313 percent) since 2000, the traffic and injuries exhibited by manta rays at German Channel have raised concerns and highlight the need for tourism management regulations.


The purpose of the study was to support Koror State and the Republic of Palau in the development of sustainable tourism management practices at German Channel. The specific objectives of the study were to investigate current site use, stakeholder perceptions and experience at German Channel to develop management recommendations that ensure the sustainability of the site.


With an average of just one to two manta rays (Manta alfredi) sighted per dive during the manta ray season (January to April), and manta ray encounters that lasted less than 10 minutes per dive in March and April, 2015 was a poor year. The majority of dive guide professionals highlighted that the number of operators using German Channel had increased since 2010, and 90 percent said that this is a having a negative effect on the site. A third believe manta ray safety is in jeopardy, and 17 percent said that the increased number of tourists and dive vessels at the site has negatively affected their tourists’ experience. The average boat-to-manta ratio was 6:1, equating to roughly 54 divers for every manta ray at the site. Both dive professionals and tourists saw the need for strict site management. Suggestions included an on-site ranger, boat traffic control, guide training and using the environmental fees currently paid by each tourist for enforcement.


In response to current site use pressure and concerns of key stakeholders, the following recommendations are proposed:

1) Boat traffic control: The creation of a legally enforceable boat exclusion zone and other boat traffic regulations at German Channel to ensure tourist and manta safety by creating legal accountability for vessel captains and operators.
2) Boat moorings and capacity: Boat mooring redistribution to avoid vessels floating above the dive site under strong current conditions, and large vessel allocation to the furthest buoys. Installation of protective cable tie streamers on all mooring lines to avoid manta entanglement.
3) On-site ranger: Visible presence of a ranger in order to deter misconduct and illegal behavior. Enacting of proper legislation to make dangerous behavior accountable by law.
4) Compulsory training: Peer-reviewing the Koror Tour Guide Certification curriculum to include conduct for diving and snorkeling and introduce compulsory guide training.
5) Public awareness: Developing an in-depth briefing and/or obligatory video on manta ray watching that explains best-in-class practices for both diving and snorkeling. Raising the profile of charismatic megafauna conservation, such as for manta rays, in Palau.

Further Information
Prieto recorded his experience on the field with three blog posts available in the Manta Trust website.
– Blog Post 1
– Blog Post 2
– Blog Post 3

David currently interns at a management consulting firm specialized in corporate sustainability strategy as well as a commercial distributed energy start-up addressing energy cost, security and sustainability.

The M.S. in Sustainability Management, co-sponsored by the Earth Institute and Columbia’s School of Professional Studies, trains students to tackle complex and pressing environmental and managerial challenges. The program requires the successful completion of 36 credit points. Those credit points are divided among five comprehensive content areas: integrative sustainability management, economics and quantitative analysis, the physical dimensions of sustainability, the public policy environment of sustainability management, and general and financial management. Visit our website to learn more.

Banner featuring a collage of extreme heat images.

Recent record-breaking heat waves have affected communities across the world. The Extreme Heat Workshop will bring together researchers and practitioners to advance the state of knowledge, identify community needs, and develop a framework for evaluating risks with a focus on climate justice. Register by June 15

Notify of

Inline Feedbacks
View all comments