It's been an eventful first few days this season on the water in Tonga. I'll write more when the charter aboard Jocara is finished, but for now, here's a preview image of the first humpback whale singer we've successfully tracked and recorded this season:
Tracking humpback whale singers isn't easy. As I explained to my fellow adventurers, in most instances you need to "out-stubborn" the whale.
Sound travels about 4.5x as rapidly in the water as it does on land, and it spreads in all directions, so it's difficult to pinpoint a specific singer's location, even when you know it's close.
Add to that complications such as limited visibility underwater, the possibility that the whale might be too deep to see, varying ambient light conditions, the effect of thermoclines, etc., and you can probably imagine why spotting singers isn't the simplest of tasks.
In any case, it took perhaps two hours, give or take, plus a lot of swimming to track this one down.
Of note, it is by far the smallest singer I've ever come across. In fact, the fluke was so small that I initially thought it might be a baby whale. I'd estimate the body length to be between nine and 10 metres.
The whale's song wasn't particularly strong. Even when I was directly above it, with the whale between 15 to 20 metres below, the whale's song didn't reverberate in my body like a full-grown whale's song would normally do.
We recorded over 40 minutes of audio using John's high-tech hydrophone array, so we have the whale on 4 channels at 24-bit, 96kHz.
We're heading out on the water again soon. More later.