Visual identification of individual manta ray (Manta alfredi) in the Maldives Islands, Western Indian Ocean

Abstract

Despite the worldwide distribution of manta ray (Manta alfredi) in tropical and subtropical regions, there is very little published information on their biology or ecology. Knowledge of the abundance of mantas and their migration patterns is essential for conservation, and the first stage in any study is a method to identify individuals. The purpose of this paper is to present a method of visual identification of individuals of manta which can be used at any site where mantas are regularly observed. In mantas, each individual has a characteristic pattern of dark markings on the ventral side. The most important individual identifying marks are patterns of ovals in the area between the gill slits, supported by distinctive patterns of mottles and spots in the lower abdominal area (posterior to the gill slits) and areas of dark pigmentation around the head and posterior wing margins. Significant changes in ventral makings have not been observed in observation periods exceeding 5 years. Scars and missing tissue may be distinctive for an individual, but significant healing may occur in 12 months. The method was designed for identification of chevron colour-type mantas, but is equally useful in identifying black colour-type individuals, and has a wider application for other mantas or marine megafauna taxa including whale sharks and cetaceans.

Keywords:

• Mantas
• scars
• ventral markings
• visual identification

Published in collaboration with the University of Bergen and the Institute of Marine Research, Norway, and the Marine Biological Laboratory, University of Copenhagen, Denmark

Published in collaboration with the University of Bergen and the Institute of Marine Research, Norway, and the Marine Biological Laboratory, University of Copenhagen, Denmark

Acknowledgements

Whilst the vast majority of sightings were made by the author with assistance from Matt Kitchen recording the observations on digital video, the significant contributions of data, photographs and video sequences by diving instructors Lisa Allison and Shaff Naeem during 2005–2007 should be recognized. The author would also like to thank all the holidaying diver observers who contributed their time and photographs. The Access database was designed by Dr Alasdair Edwards, Newcastle University.

Notes

Published in collaboration with the University of Bergen and the Institute of Marine Research, Norway, and the Marine Biological Laboratory, University of Copenhagen, Denmark