Unidentified whale signals recorded in Cook Strait

A NIWA led research team have confirmed the presence of beaked whales by analysing underwater acoustic data collected during two six-month long deployments of six fixed passive acoustic moorings (PAM technology).

A reviewed subset of the data collected detected three distinct beaked whale signals. One matched the Cuvier beaked whale, one of the more commonly seen beaked whale - the other two do not match any previously recorded beaked whale species. 

Over half of all whales and dolphins, known as cetaceans, are found in New Zealand waters but very little is known about their population sizes and seasonal distribution patterns. Particularly elusive are the beaked whales, of which 13 of 22 known species have been found in New Zealand.

Beaked whales are deep diving animals and spend more than an hour on a single dive and surface for very short periods of time.

"Most information about their presence in New Zealand waters has come from people reporting whale strandings but it is very limited. We really know very little about their behaviour" says NIWA marine mammal expert Dr Giacomo Giorli.

Dr Giorli speculates that the most likely possibility for the owners of the unknown whale signals, based on stranding records, is that the signals belong to the Gray’s and strap-toothed beaked whales. However, he says that matching the recordings can only be done via concurrent visual and acoustic observation which has yet to occur. 

The utilisation of the PAM technology in the Cook Strait is the first project of its kind in the area. PAM systems monitor and record the sound of everything in the vicinity including vocalising cetaceans, natural noises such as wind, waves and earthquakes and man-made soundscape contributions like boat traffic and oil and gas exploration.

A paper detailing the findings has been published in The Journal of the Acoustical Society of America.

• Unknown beaked whale echolocation signals recorded off eastern New Zealand