Distribution, site affinity and regional movements of the manta ray, Manta alfredi (Krefft, 1868), along the east coast of Australia

Abstract

Abstract. Despite the increasing tourism interest worldwide for the manta ray, Manta alfredi, very little is known about its biology and ecology. Knowledge of its distribution and movement patterns is important for conservation purposes. Here we describe the distribution, site visitation and movements of M. alfredi along the east coast of Australia. Photographic identification techniques were used to identify individual manta rays at three study sites: Lady Elliot Island, North Stradbroke Island and Byron Bay. Of 388 M. alfredi individuals identified at Lady Elliot Island, 187 (48%) were subsequently re-identified at least once at the same site. In total, 31 individuals were identified at both Lady Elliot Island and North Stradbroke Island (,380 km to the south) and 4 at both Lady Elliot Island and Byron Bay (,500 km to the south). Manta alfredi was present all year around at Lady Elliot Island, although in higher numbers in winter, and was mainly observed at North Stradbroke Island and Byron Bay from mid-spring to mid-autumn. This is the first report of seasonal movements and site affinity for M. alfredi in eastern Australian waters and emphasises the value of photographic identification for monitoring the occurrence of individuals.

Movements and habitat use of reef manta rays off eastern Australia: offshore excursions, deep diving and eddy affinity revealed by satellite telemetry

“…Ten Manta alfredi were fitted with pop-off satellite-linked archival transmitting (PSAT) tags during austral winter 2010 (n = 2), summer 2010-2011 (n = 2) and winter 2011 (n = 6; Table 1). Prior to tag deployment, each individual was identified, its size (disc width, W D ) was estimated and its sex was determined using conventional manta ray photographic identification and laser photogrammetry techniques (Deakos 2010, Couturier et al 2011, Marshall & Pierce 2012. Tags were deployed on free-swimming individuals while free diving using a 320 kg Dyneema braid leader and an umbrella-shaped plastic dart inserted into the dorsal musculature, away from the body cavity, with a customised tagging pole.…”

“…Until recently, most of the movement data available for manta rays had been derived from re-sightings of photographically identified individuals over relatively long time periods (e.g. Kashiwagi et al 2010, Couturier et al 2011 or from acoustic telemetry data (e.g. Dewar et al 2008, Deakos et al 2011.…”

“…Dewar et al 2008, Deakos et al 2011. Such technologies provided the first insights into the movement ecology of manta rays, highlighting diurnal visitations of reef manta rays Manta alfredi to particular inshore sites (Dewar et al 2008, Marshall 2008, movements between aggregation sites up to 500 km apart (Kashiwagi et al 2010, Couturier et al 2011) and seasonal migratory patterns in some regions (Anderson et al 2011, Couturier et al 2011. More recent telemetry studies have, for the first time, documented the movement patterns of both giant manta rays M. birostris and reef manta rays M. alfredi foraging in shallow habitats off the Yucatan Peninsula, Mexico, and in the Line Islands of the central Pacific, respectively (Graham et al 2012, Papastamatiou et al 2012.…”

“…In eastern Australia, M. alfredi occur at various localities along the coast, with some individuals seasonally migrating between sites up to 500 km apart (Couturier et al 2011). One major aggregation site for M. alfredi is Lady Elliot Island (LEI) (Couturier et al 2011), a small coral cay in the southern Great Barrier Reef (GBR), located only a few kilometres from the continental shelf edge (see Fig.…”

“…One major aggregation site for M. alfredi is Lady Elliot Island (LEI) (Couturier et al 2011), a small coral cay in the southern Great Barrier Reef (GBR), located only a few kilometres from the continental shelf edge (see Fig. 1A).…”