New Season in New Zealand

January 2021

The Manta Watch New Zealand (MWNZ) team have been gearing up for an intensive few weeks of manta surveys starting at the end of December. Working in partnership with Conservation International (CI) the project will, for the first time, have a dedicated manta research vessel. Yay! To celebrate the launch of the NZ Manta-Mobile we’re excited to share our new project logo, that will take pride of place on our new boat. Special thanks to the incredibly talented Te Kaurinui Parata for this beautiful commission.

Manta Watch New Zealand’s new logo.

The new logo on the Manta Watch New Zealand research vessel.

Our primary objectives this season are to collect manta IDs and to deploy CI’s satellite tags. If successful, this supplementary tagging project will massively advance our collective knowledge and understanding of the oceanic manta rays in Aotearoa New Zealand. All we have to do now is find some mantas! With just under 200 verified sightings we have a pretty good idea of where to look and what to look out for. However, due to our extensive search area, sightings success is determined by ocean conditions. Light winds and minimal swell give our researches the best possible chance of spotting mantas. Drones, both above and below the water, dramatically increase our spotting capabilities as we track down this highly elusive species.

Most commonly, NZ oceanic mantas are encountered whilst cruising i.e. not actively engaged in another behaviour. This is when individuals are at their most stealthy, slowly swimming at or just under the surface of the water, occasionally showing their wing tips and a manta sized ripple. During these instances you need to be pretty close to or right on top of the manta to spot them.

Courtship occurs throughout the season and is much easier to spot, as it involves a lot of wing slapping and splashing on the surface as the male manta rays chase the females in anticipation to mate. This energetic exchange is mirrored under the water as the mantas whizz around doing somersaults and tight circles as part of their courtship display. Very little is known about oceanic manta ray courtship, making these encounters incredibly informative! The females also seem to welcome the distraction of a human observer, tending to use this useful addition as a way to dislodge her attentive mate!

Coming across a manta feeding aggregation is like winning the lottery. The oceanic manta rays enthusiastically somersault to catch their highly mobile zooplankton prey, krill. More often than not, they’re way too preoccupied with gorging themselves to mind an opportunistic ID shot!

Oceanics are known to change their feeding behaviours depending on what prey species are available and when. During New Zealand’s summer, warm currents from the north mix with the cool, nutrient rich waters, of the south producing plankton blooms. Upwelling occurs on the continental shelves and around the offshore islands, often flowing into the relatively shallow and sheltered waters near the mainland. Dense swarms of krill feast on the phytoplankton which in turn attracts numerous fish and seabird species, eager for a feed. When this happens, groups of oceanics can be seen feeding together. Last season we received an account of numerous oceanic mantas and scores of spine-tailed devil rays all feeding together.

This is our dream scenario and we can’t wait to get in the mix!