Success in the Kaikoura Canyon

February 19, 2013

Will Rayment with hydrophone.
(Moira Brown, NEAQ)

There is nothing quite so sweet as success.

Today we set a watch on the top deck and started running a grid search pattern to survey the outer parts of the canyon for sperm whales.

In addition, we deployed our secret weapon out in the ship's tender in the form of Will Rayment from the University of Otago. His routine is to steam along, shut the engine down, and use a small, handheld hydrophone to listen for sperm whale clicks. Rotating the hydrophone allows him to determine of the direction from which the clicks are loudest, indicating the direction to head, to listen again.

As the boat gets closer to the whale, the sounds become louder and more "surrounding." At that point we wait and listen.

The whale will stop clicking before it surfaces--all eyes are peeled and as if by magic, there is the whale close by. Then we gently idle over in a Zodiac and apply the tag.

Leigh Hickmott ready to apply the Dtag.
(Marta Guerra, Univ. of Otago)

It sounds easy, and indeed this morning, that is just what we did. Leigh Hickmott, a veteran tagger from St. Andrews University plied his skill, and was able to attach a tag to the right side of the animal. It was not a very secure attachment, as not all four of the suction cups seemed to hold, but enough, the tag stayed on for its programmed three hours, came off and floated back to the surface, where we were able to retrieve it.

Tag secured (for the moment) and ready to record.
(Marta Guerra, Univ. of Otago)

There was a wonderful scene in the lab this evening as we all crowded around the laptop as Julie van der Hoop, A graduate student in the MIT/WHOI Joint Porgram, downloaded the data and made the first plots. So, for the first time we were able to get a sense of what these animals are doing at depth. It underwent 3 dives while it was tagged: two to 500 meters, and then the last dive before the tag detached went to 1000 meters, where the animal could be heard buzzing, which is a good sign of foraging activity. Getting new information about the dive behavior of these animals in this habitat is an important contribution to efforts to conserve this species.

Our work to better understand short and long term responses to stress are all coming along, albeit on a slower track than the Dtag work, but stay tuned for updates in that regard in coming days.

Dive trace of a sperm whale in the Kaikoura Canyon. (Julie van der Hoop, WHOI)