2009 04 20- 16 more fluke ids and 11 of them match the large group on 19th of April Print E-mail
Written by Andrew Stevenson   

Photo by Kelly Winfield

We set off at 8.30am on Sea Slipper with Michael Smith, Camilla, myself, Kelly, Sophie and Alex. We pick up one whale apparently feeding on the outer ledge heading towards Sally Tucker's, get his fluke id and then continue around Sally Tucker's to the north and then head across the canyon. We are almost on Challenger when we pick up a couple of whales heading back to Sally Tucker's. We follow them at a steady five to six knots on a set heading although there are now three whales travelling on parallel courses but separated by some hundreds of yards. A breach by one is answered by another, and then they continue to the edge north of Sally Tuckers and breach or tail lob and begin to feed where we get some fluke ids and then leave them. Crossing back to Challenger we come across another whale feeding on the edge as he surfaces right beside the boat, blows a couple of times and then dives back down to feed.

While crossing over to Challenger we came across streaks of Velella velella (By-the-wind sailor), the oval little jellyfish with the sail, and its predator, Janthina pallida (Pale-purple Ocean Snail), with its bubble float and egg mass, and attached stalked barnacles (Lepas sp.) The tiny round things we found floating on the surface are Foraminifera (single-celled animals with a skeleton). The Pale-purple Ocean Snails floating on their rafts of bubbles have rather fragile, globular shells and are planktonic, that is they making no attempt at swimming. They are widely distributed, and along with other plankton, are swept across the ocean by wind currents. Pale-purple Ocean Snails typically attach upside down to the underside of the hydrozoan, Velella vellella (which they also feed on and which were all around them when we found this batch), a primitive colonial coelenterate resembling the jellyfish, where they float and feed on the hydrozoan. If not attached to hydrozoans, Janthina snails may also construct a buoyant raft from a tough, transparent, bubble which it secretes from its foot and which you can clearly see in the photos below. Inside these bubble rafts were their egg masses. I took several specimens to Dr Wolfgang Sterrer at the Bermuda Aquarium and Zoo for their collection, and for a closer examination of their eggs. These purple sea snails secrete a mucus with a blue-purple dye, which stained the water in the container a rather pretty colour.

  

When we finally got out to Challenger it was mid-afternoon. We found numerous whale blows but the whales were elusive. We obtained 16 individual fluke ids, 11 of which were the same whales from yesterday. But even more remarkable is the similarity in fluke patterns. Some of them you really had to look hard to see the differences. Following the large group around for some hours it struck me that there were numerous females as well as males, juding from the dorsal fins and it seemed that while some were enormous, others were smaller whales, perhaps even junveniles.

The fluke ids today suggest once again that the humpbacks here are meeting in family associations. There was some jostling around, but nothing like the rowdy groups of the Caribbean. Could the whales not only be aggregating into protective convoys on these seamounts, but also into large family associations? Of the 28 individual whales we saw today, over half of them were category 1, that is to say, had less than 25% black on while. Not only that, but all of these had the same general pattern differentiated mostly by scars. Of those with 25-50% white/black pigmentation, there were some distinct patterns rarely seen, but four of these whales had these distinctive circular templates.

Eventually I got into the water with a surface active group of five whales for some underwater video. At 5.30pm the light was getting bad in the water so we left the small group and headed back to Bermuda, getting to the dock at 8.30pm while Michael got ashore around 11pm after mooring Sea Slipper. Without Michael's enthusiastic support, we wouldn't be able to get out on the water as often as we do. I hope he knows how much we appreciate it.

 

 
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