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.