December 4, 2017, by Alex Ravelo

Sounds in the Sound: a mission to record whales in Sitka Sound

by Kate Stafford

Part 1

We had our “sounds in the sound” kayaking trip to Eastern Channel on Tuesday under calm winds and sunny skies. Unfortunately the whales didn’t cooperate as they had moved to Sitka Sound – we only saw a few blows in the distance.   We did put out dipping hydrophones (underwater microphones that you hang off a boat or kayak) and listened to the sounds of waves, kayaks bumping each other and numerous small boats zipping around Eastern Channel. Everyone was surprised at how much sound the engines of small vessels put into the water.

Jan Straley and her students have been listening to and documenting the many sounds humpback whales make in Sitka Sound which include moans and grunts and feeding calls and, in the fall and winter, song.

For community members who didn’t want to kayak, Davey Lubin took a group out with Jan Straley and they recovered an underwater hydrophone that had been put out two days before in Eastern Channel from Ernie Eggleston’s boat. They also put the dipping hydrophone in to listen for whales and, like the kayakers, heard very little.  And when the data were downloaded from the instrument that had been underwater, there were a few feeding calls and other vocalizations as well as some really faint song.

 

Part 2

Humpback whale males produce long elaborate songs in the winter that are thought to serve a dual purpose – let other males know something about the size or age or social status of the singer – but also to let females get an idea of whether the male might contribute good genes (make a good father).  Songs are usually made on breeding grounds in the tropics (Hawaii, Mexico, Asia) and all males sing the same song during the winter. Singing on the breeding grounds can last hours or days. It is not known how long singing lasts on the feeding grounds.  One song can last minutes or hours and consists of several themes repeated over and over.  More and more, songs are being heard on what are traditionally considered feeding or summering regions like Sitka where humpback whales are increasingly being seen (and heard) through the winter. It is thought that males might be “practicing” before heading south or males who might not migrate but still sing in the winter How song changes across a population from year to year is speculated to happen on the feeding grounds.

Since most of the humpback whales moved out of Eastern Channel, on the Wednesday before Thanksgiving, Jan, Lauren Wild and Kate Stafford headed out with the hydrophone, line, an anchor and a float and deployed the instrument in a region where there were easily over 50 whales spread out from south to north to west. We put the dipping hydrophone in and heard a number of sounds from whales including feeding calls.  Four days later we headed out on Dave and Lisa Moore’s boat to retrieve the recorder and were again in the midst of lots of whales. When we downloaded the data from the second deployment in the first few hours we heard lots of feeding calls and one really loud song!

Here is a snippet of the hydrophone recordings (Tip: increase the volume of your speakers to get the full experience)