June 27th marked the end of a very successful summer field season. After waiting for workable weather for almost a week, the wind finally died down on Friday, only to be replaced by rain and thunderstorms. We waited out the lightning and the rain at the Oregon Inlet Fishing Center and got a late start, but it was worth it as we ran into pilot whales as soon as we arrived at the shelf break just after noon.
The whales were moving steadily south along the break and we quickly had a DTag on a large male. Conditions were good and the group was co-operative, so we decided to deploy a second tag in the same group – the elusive ‘Double Tap’ of whale tagging. (Who doesn’t love a zombie comedy with Bill Murray in it?)… Soon, we had two whales tagged and things were going swimmingly.
That is, of course, until our group decided to join another couple of hundred pilot whales in a feeding aggregation that also included about 15 charter boats, commercial troll boats and recreational vessels. Fishermen often target groups off pilot whales, believing that they ‘carry’ tuna underneath them. It is likely that the pilot whales and tuna are both attracted to the same prey (squid), so the strategy is a good one – we saw several boats hooking up with fish while we were dodging and weaving trying to stay out of the way. It was difficult to keep track of our two tagged whales in all the action, but we persevered.
Matt’s initial look at the dive data from the two tagged whales shows that they were quite synchronous throughout the afternoon. An early foraging dive was followed by steady travel to the big aggregation, followed by long dives of 10-15 minutes in duration and to 400 m in depth, interspersed with resting periods at the surface. This is typical pilot whale foraging behavior, but it’s cool to be able to document simultaneous behavior of the two animals.
We managed to complete a full playback sequence with the two whales and both tags came off exactly as planned, at the end of their planned deployment periods. We had both tags back in the boat and were on our way home by 5:00 PM. A great end to what has been a really productive field season.
