Friday, August 16, 2013


A DTAG sits on an adult pilot whale, ID#248
Dive record of a tagged adult pilot whale
Imagine diving down to a depth of 800m.  

It's extremely cold, ambient pressure is 80 times higher than at the surface, and the only trace of light is given off by small bioluminescent organisms.  Now try to find a dozen decent-sized meals, all while holding your breath for 15 minutes.  A typical pilot whale will do this many times in a single day.

Using our tags, we can study this foraging behavior in great detail.

The suction- cup DTAGs that we deploy not only capture acoustics but are also equipped with sensors that measure the 3 dimensional movement of the animals and their depth.

Here is an example of one of our large tagged adult pilot whales, ID# 248.  As you can see in the figure, this animal was making deep dives down to the bottom of the Strait, likely foraging on prey such as  squid that they hunt with their echolocation clicks.

We know from studies of the stomach contents of stranded pilot whales that most of their diet is composed of squid, but we have very little idea of when, where and how often they capture these prey.  The sensor data from the tags we deploy gives us a window into the basic ecology of these echolocating predators.  With multiple simultaneously tagged animals we can even see how the whales are interacting at depth and whether they are foraging in the same place or at the same time.

Nicholas Macfarlane

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