Oceanic Manta Ray Surveys with Manta Watch New Zealand

Research Team

• Lydia Green
• Dr. Mark Erdmann, Ph.D

Project Overview

Despite being fully protected in New Zealand waters since 2011, under the Wildlife Act, the biggest threat to Aotearoa's oceanic manta rays is the lack of data. We simply don't know enough about this lesser known population to provide adequate protection or establish long term conservation management. To inform change, vital data relating to population dynamics, behaviour and habitat need to be collected through underwater video / images, aerial drone and satellite tag deployments.

Duration of Project

Ongoing

Expedition Summary

During April 3rd - 4th, 2024, The International SeaKeepers Society South Pacific facilitated a 2 day expedition aboard DISCOVERY Yacht Saluté. The expedition included conducting oceanic manta ray surveys, photographic images for identifying individual manta rays and the attempt to deploy satellite tags. The trip focused its efforts off Great Barrier Island in the Hauraki Gulf and in between the Hen and Chicks islands. We spotted 4 mantas and 1 devil ray, got 2 ventral (belly) IDs, and 2 dorsal (head) ID's and attempted to deploy 2 satellite tags. This data is important as it is late in the season for typical manta sightings so the data collected will give the team a better understanding of oceanic manta ray movements in New Zealand.

Application

By using the height of DY Saluté to our advantage we started our surveys by keeping an eye on the water for any disturbances that were conducive to manta feeding behavior. Once a manta was spotted we deployed the drone to observe the mantas behavior, identify the gender, and get a dorsal and ventral ID. Every manta ray has a unique pattern of spots on its ventral surface or belly, that remain unchanged throughout that individual’s lifetime. The unique nature of these spots is incredibly helpful for manta scientists, enabling individual mantas to be identified just by photographing their belly’s.

Location

Hauraki Gulf, New Zealand