Restricted movements of juvenile rays in the lagoon of Ningaloo Reef, Western Australia - evidence for the existence of a nursery

Abstract

Little information is available on the movements and behaviour of tropical rays despite their potential ecological roles and economic value as a fishery and a tourism resource. A description of the movement patterns and site fidelity of juvenile rays within a coral reef environment is provided in this study. Acoustic telemetry was used to focus on the use of potential nursery areas and describe movement patterns of 16 individuals of four species monitored for 1–21 months within an array of 51 listening stations deployed across a lagoon, reef crest, and reef slope at Mangrove Bay, Ningaloo Reef, Western Australia. Juveniles used a small (< 1 km2), shallow (1–2 m depth) embayment where three receivers recorded 60–80 % of total detections of tagged animals, although individuals of all species moved throughout the array and beyond the lagoon to the open reef slope. Detections at these primary sites were more frequent during winter and when water temperatures were highest during the day. Long-term use of coastal lagoons by juvenile rays suggests that they provide an important habitat for this life stage. Current marine park zoning appears to provide an effective protection for juveniles within this area.