Study to uncover secrets of hidden manta ray habitat

An urgent exploratory study is underway after the discovery of an unknown manta ray habitat off the northern tip of UNESCO World Heritage-listed K'gari, the world's largest sand island.

University of the Sunshine Coast Associate Professor Kathy Townsend said the researchers made the unexpected find after recently satellite tagging five manta rays near Lady Elliot Island, at the southern end of the Great Barrier Reef, approximately 120km north-east of K'gari.

"To our surprise, all five individuals headed south to the northern tip of K'gari, an area known as Long Shoals, and the data downloaded from their tags suggests it may be an important feeding, breeding or nursery site," Dr. Townsend said.

The UniSC research team says it now needs to urgently determine how many manta rays are at the site, examine behavior and habitat use, and also assess any threats from commercial fishing, bycatch and boat traffic and if the current levels of protection are adequate for this vulnerable species.

"As part of our investigations, we plan to conduct drone surveys and behavioral observations, measure individuals and sample their food resource—zooplankton," Dr. Townsend said.

But this presents some major challenges.

"Due to the limited access to the site and harsh diving conditions, it is very difficult to confirm what we are seeing in the satellite data with direct observations and measurements," Dr. Townsend said.

So UniSC and the Project Manta team has teamed up with Wildlife Warriors and the Butchulla Native Title Aboriginal Corporation (BNTAC) Indigenous land and sea rangers to seek answers.

Wildlife Warriors is providing a research vessel as the platform for researchers to reach the manta rays, and BNTAC's Djaa Narawi Ranger program will assist the team with data gathering. Kingfisher Bay Resort on K'gari will accommodate the scientists and rangers for the first site visit from 9–16 July.

"Wildlife Warriors is delighted to be supporting Project Manta and the University of the Sunshine Coast with their research into the population of manta rays off K'gari," Dr. Terri Irwin AM said.

"Our Wildlife Warriors team will be operating Croc One, a vessel designed for scientific work, which will allow the researchers to further their studies vital in the protection of this iconic species," Dr. Irwin said.

Project Manta, now based at the University of the Sunshine Coast, has been actively researching manta rays in Australian waters since 2006 to unlock the mysterious life of the world's largest ray.

"In that time, we've gone from having little scientific knowledge about Australia's mantas, to being made aware of a second species," Dr. Townsend said.

"We've gathered extensive insights into their ecology and biology, and building a national database of over 3,000 individuals."

Research activities include acoustic and satellite tagging to observe migration patterns, and genetic sampling to determine population size and connectivity to locations in Australia and internationally. Tools such as plankton tows and satellite oceanography are used to investigate feeding and movement behaviors.

Dr. Townsend says this latest discovery reinforces that there is still much to learn about these enigmatic, graceful sea creatures.

Project Manta started on the east coast of Australia at two main study sites—Lady Elliot Island and North Stradbroke Island—before expanding to a national partnership between UniSC, the University of Queensland, Murdoch University, and industry partners.

Provided by University of the Sunshine Coast