Sunday, August 23, 2009

Chances early...then more of the same

Today dawned much calmer than expected and we were on animals both visually and acoustically quickly. We searched around our first beaked whale acoustic detection and soon thereafter had a visual sighting. We also crossed paths with a large group of common dolphins (50 animals or more), saw some large Risso's dolphins riding on the bow of a nearby large ship, heard pilot whales, and saw a large tuna leap several times in the air with a large fish in it's mouth. We followed one promising group of three adult/sub-adult Cuvier's beaked whales, tracking them both visually and acoustically (see below), and had our tag boat over the side and ready to go. But we hadn't managed to tag them by about 1100 and the wind picked up from the east again rather quickly and by noon we had the Beaufort 5 conditions described yesterday that were predicted for today. We continued searching for pilot whales, but by mid-afternoon the winds again ended our day early.

During the mid-morning focal follow on the beaked whale group, we demonstrated again an effective capability to integrate information received from our visual and acoustic teams to position the ship relative to animals while adjusting for other environmental factors as well. In the figure here, you can see the track of the ship as the orange symbols in a line beginning in the southwest (lower left) section of this GIS plot; the closer together the symbols the slower the ship and the further apart the faster the ship. As we moved to the northeast, we had a visual sighting (red C1) of a beaked whale, identified as a single animal. We continued forward and had a subsequent acoustic detection of beaked whales (seen as the pink circle on top of the ship's track) and an approximate bearing to the animals ahead of and to the starboard (right) side. About 25 minutes later we had two good visual sightings of a group of three beaked whales (red C2 and C3) at the surface and had clear direction bearing (heading) for them to the northeast (direction of arrows). The animals then did a shallow dive that we expected would take another 15-30 minutes. Now we had a choice - and a problem. It was still morning at this point. The sun was coming up in the southeast and there was a serious glare on the sea that would prove difficult for our visual observers if we did not adjust the position of the ship relative to the whales. So we turned toward the sightings, sped up significantly (note the orange symbols spacing out), and cut behind them while maintaining acoustic detection. This maneuver worked perfectly as we passed them and then slowed down, turning to the north while continuing to hear them now off our port (left) side (additional small pink circles along ship track). The two purple lines show two of the acoustic bearings which predict direction to the animals underwater; they are close enough in time that where they cross is an estimated location. Using the sighting location, visual bearing, and these acoustic bearings, we had a good prediction of where they were and where they might come up. Now we had the sun on our stern (back) and also a better orientation to the significant current from the east as well. Ultimately we were precluded from seeing them come up despite, being in an ideal position, because throughout this maneuver the wind jumped from 5 to 15+ knots. Nevertheless, this kind of fairly complex tracking with integrated visual and acoustic information - reading the animals using these tools and orienting ourselves correctly relative to the sun and the current - demonstrates that everything is working together quite well.

The wind is dropping this evening and we hope to catch a nice calm window tomorrow as the wind switches from the east to the west. If we get flat seas we know the animals are here and that we are ready.