The blue whale barrel roll

Some extremely cool research has come out recently on blue whale feeding behaviour, which explains what I often see from the boat. Below is a photo that I took in 2011 and another I took last last week in the Corcovado Gulf. What you can see sticking out of the water is the blue whale's pectoral fin (its flipper) which indicates that the animal is rolled onto its side as it lunges through the water. We have often referred to this at lunge-feeding behaviour or a lateral lunge, where the whale rolls onto its side and takes a huge gulp of water and krill and then rolls upright again.

Blue whale lunge feeding, 2011.
Credit: Susannah Buchan

Blue whale lunge feeding, February 2013.
Credit: Susannah Buchan

This new research is summarized in this video, which shows the simulation of blue whale feeding behaviour off the coast of California, based on data collected with suction cup tags and images collected with a National Geographic crittercam. This is so incredibly cool! Take a look:
http://www.sciencefriday.com/video/12/07/2012/blue-whale-barrel-roll.html

This simulation shows feeding at almost 300 m depth. This is interesting because here in the Corcovado we often see whales feeding at much shallower depths, in waters of say 130 m or even less, and we see these  lunges at the surface. I am not sure if this shallower feeding is common elsewhere, but it is surely linked to the oceanographic conditions that determine krill patch distribution, which I am researching as part of my PhD. It would be amazing to replicate this study here in southern Chile, where the oceanographic and krill distribution characteristics are very different from the Californian upwelling system.

Summer field season so far: a selection of photos

I have been in Melimoyu for about three weeks and we have had good luck sighting whales and sampling the feeding ground. We have seen quite a lot of deep dive behaviour and some lunging behaviour which indicates exploratory dives for food and feeding.

Here is a selection of photos:

Blue whale and the Melimoyu volcano.
Credit: Susannah Buchan

Blue whale diving in front of Islote Locos.
Credit: Susannah Buchan

Blue whale dive.
Credit: Susannah Buchan

Blue whale diving in front of Islote Locos.
Credit: Susannah Buchan

A lovely blue whale blow. 

Credit: Susannah Buchan

 We have been working on board the research vessel Anihue which has been helping us from the nearby Anihue Reserve. They also have an echosounder which is really useful for sampling krill. 

Credit: Susannah Buchan

Plankton soup! Taken from near diving blue whales.
Credit: Susannah Buchan 

Plankton patch showing up on the Anihue boat echsounder. We got a good krill sample  in our net when we targeted this patch. See photo below.
Credit: Susannah Buchan

Krill soup!
Taken from near diving blue whales with the help of the echosounder on board Anihue.
Credit: Susannah Buchan