Manta rays, which can reach up to nine metres wingtip-to-wingtip, are found in the Hauraki Gulf (file image). Photo: Supplied / Manta Watch NZ
Manta rays visiting New Zealand are under threat from pollution and boat strikes.
The Department of Conservation has assigned manta rays the threatened status after a new report found numbers were dwindling.
Their status is now 'Threatened - Nationally Vulnerable' when they were previously 'Data Deficient'.
"This change represents a greater level of concern for the species than previously held," DOC said in a statement.
The manta rays are one of 113 species who were assessed by an independent panel for the latest conservation status report about New Zealand's chimaeras, sharks and rays.
Senior Science advisor Dr Karen Middlemiss said manta rays spend about six months in New Zealand waters each year when it's warm.
But DOC staff often find them injured.
"In New Zealand waters the sorts of things that we find impacting them are pollution in the waters, habitat degradation, disturbance in key aggregation sites, and vessel activity can also play a role, Middlemiss said.
"We often find animals that have got evidence of boat strikes."
Middlemiss said current estimmates suggest there are just a few thousand manta rays in New Zealand - but further data is needed to confirm this.
"We know very little about our manta ray population size, age structure, and regional connectivity with other Pacific populations."
Basking shark from above and underwater (file image). Photo: Left Basking shark from above - credit rossbeane, some rights reserved (CC BY-SA) Right Basking shark underwater - Photo credit Greg Skomal - NOAA Fisheries Service [Public domain]
Meanwhile, Basking and Plunket's sharks are now considered 'Threatened - Nationally Critical' - the last status before extinction.
"The disappearance of the basking shark from New Zealand's shores is very concerning, and we don't know exactly why this has happened," Middlemiss said.
"Urgent research is required to better understand population pressures - both human induced and environmental - to inform conservation management decisions for both basking and Plunket's sharks."
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