18 November – Small Boating In Antarctica

 Another creature that's interested in zooplankton distributions in Antarctica was this baleen whale that we saw during our small boat survey yesterday.

Part of my research here in Antarctica is applying acoustic techniques (as described very nicely by Peter in the  previous blog post) from a small research vessel (normally a 6 m long inflatable rubber boat). Some of you (particularly my mother) might question why one would do such a thing. Travel to Antarctica and then ride around in a tiny boat ?

But there are several reasons that the small boat survey platform is particularly useful down here. Occasionally, you may read in the news about a ship running aground in Antarctica (it happened last year with a tour ship not very far from where we are now). This often happens because the bathymetry (how deep the water is) in this area is not very well charted.  There have been very few systematic mapping surveys of Antarctic waters, so boats tend to be wary (with good reason) of 1) going to places they haven't been safely before and 2) going near the islands or other shallow areas.

In addition, a 250+ ft long research vessel is a fairly loud boat, particularly underwater. The smaller research vessel that I use has a lot of advantages in studying zooplankton populations here, particularly close to shore.  It has a very shallow draft (~ 1 m) so we can go very close to shore and work in very shallow water, it is very nimble, it is much quieter acoustically, and our echosounder is located about 1m below the surface so we can collect data in the near surface waters. Additionally, we can monitor krill predators that may be in the area and they are not (to our knowledge) avoiding our vessel.

So yesterday morning was the first calm day we've had on this trip, so we jumped on the opportunity to take the small boat out and conduct some survey work. It provided a nice opportunity to also use three different acoustic systems to study the same volume of water which can help us later on (after the cruise) in interpreting and comparing the data from the three acoustic systems with each other.

So myself and MTs Kelley and Krista went out for a ~ 3 hour cruise (somewhat reminiscent of Gilligan's Island, I know).  There was some good size swell coming through, but once you're in the small boat and away from the large boat, it was not that noticeable.

We had several islands in the distance that would disappear and reappear as we rode up and down the wave crests during our U-shaped survey trackline (we covered about 20 km in the 3 hours). About 20 minutes into the survey, Kelley who was driving the zodiac mentioned “hey, is that a whale's footprint there ?”.  A whale's footprint is a circular area of the ocean which is caused by the whale moving it's tail fluke either at the surface or just beneath the surface. Sure enough, there was one.

  The calm, circular area of smooth water is the “whale's footprint.” Which means there's probably a whale around here somewhere.

A couple of minutes later, we spotted a splashing at the surface and saw a bit of a fin poking out of the water.

This is one half of the whale's tail fin (or  fluke). Seeing this means the whale is on its side swimming close to or at the surface.

It was difficult to ID the whale as it was moving very quickly, popping up on one side of the boat, then a few minutes later on the other side. Occasionally you could see a white shape moving underwater near the boat which was the whale's belly (which was very white) as it swam belly-side up past our boat.

 It may be tough to see, but the white shape submerged is the belly of the whale as it swims “upside down” in front of our research vessel.

We finally got some good photos of the whale and could estimate that it was about 20 ft in length (about the same size as our boat!) and from it's coloring, I'm pretty confident that it was a Minke whale. (the other possibility is the dwarf minke whale, but the pectoral fin coloring indicates it's a Minke.

 At one point, the whale surfaced along our starboard side and swam along with us for a few seconds

In addition to seeing the minke whale, we also saw a few small groups of chinstrap penguins (no photos unfortunately) during our survey. I was somewhat surprised that we didn't see more animals that feed on krill as there was a lot of krill in the water according to our echosounders. The Minke whale may have been feeding as there was krill close to the surface (about 10 m deep) or it may have just been curious about the weird looking “whale” that was driving around next to it. It was a great day to be in the small boat and we were able to test out and use our equipment which worked well. Now we just need to have another good weather day to get back out there.

Joe
(note: that day is not likely to be anytime soon as once we got back on the LM Gould yesterday, the winds have been steady at 30-40 kts).