Conditions started off just perfect today – almost no wind (Beaufort 0-1 conditions) and just a light swell. This is exactly the kind of conditions that you have to have if you stand any chance of finding and tagging the elusive beaked whale. We were forunate to have access to the wired listening range and we started off on a hydrophone that was active with beaked whale sounds. Soon there were Cuvier's beaked whale clicks on multiple phones to the south and west and we sent first one small boat then both in those directions, followed shortly thereafter by the Sproul.
Shortly, one of the small boats was on a group of five beaked whales and before we knew it they had tagged an adult male in the group with two other adults and two sub-adult animals. This was the first
Cuvier’s beaked whale tagged with an acoustic recording tag in the Pacific and we were correspondingly excited. We immediately began preparing and checking everything for a rare and important sound exposure experiment, and continued monitoring the group with the tagged whale. This soon became complicated as the group of five was surrounded by not only ten other Cuvier’s beaked whales, but two Baird’s beaked
whales identified in the same area (about a 4x4 mile area). Seeing 17 beaked whales in a day is pretty uncommon, but was largely the result of just glass calm seas.
We sorted through who was who, focusing mainly on the tagged whale thanks to being able to monitor the radio frequency being emitted from the tag and synching it with visible surfacing behavior. In addition to the (unusual) complication of possibly too many beaked whales in the area all diving and submerging somewhat synchronously, we also had some
weather to deal with. Right around the time that we were ready to start a sound exposure experiment, a heavy bank of fog rolled in. We have specific protocols for having sufficient visibility to monitor the area around the area of any sound transmissions to a range of 1,000m and we were at times down to 300m visibility, so we had to wait. With beaked whales, waiting from one deep foraging dive to another is a multi-hour exercise, and so it was noon before we were ready to go again.
Fortunately there was a several hour gap in the fog and the timing worked out well with their dive behavior, and the density of animals had dropped by that time so we were not exposing too many other
animals incidentally as well as the focal whale. Monitoring of the whale during the exposure study was conducted by multiple acoustic sensors to ensure it was still diving and not reacting in some strong aversive manner. None was seen during the 30 min of intermittent sound transmissions, nor were any other animals seen to react in a strongly aversive way during the study. A dedicated post-monitoring survey of the area by multiple boats was conducted.
As often happens with beaked whales since they stay down so long (his earlier dive was about an hour) and can cover large distances under water, we didn’t find him again after the sound exposure dive. But earlier in the day, the tag had been seen to slip somewhat back and down on the animal so that the radio transmitter was less out of the water and was obstructed by the animal. The fact that it is not being received then (or now at night) probably means that it is still on the whale and will come off near or at the 0400 scheduled time tomorrow morning. We are scanning the area for the tag doing transect surveys and monitoring throughout the night on a regular basis. I will try to put up a post later in the night or in the morning when we are searching for and hopefully finding the tag with all our data on it.
This was the first controlled sound exposure experiment of any kind with simulated military sonar or other sounds, on a Cuvier’s beaked whale. These animals appear to be the most sensitive of the particularly sensitive beaked whale group and these are thus very valuable bits of information to have about responses in this species. We are not getting too excited until we get our tag back, but we are guardedly optimistic and happy that we were able to get done what has proven to be so very hard to do. It was an amazing day today and we saw Dall’s porpoise, two beaked whale species, lots of dolphins of different varieties, and omniscient sea lions as well, plus a 10-foot great white shark slinking along. Two days left for SOCAL-10 – it was nice to round things out with getting some work done on a high importance species like a beaked whale. It was the ninth different species tagged in this project.
Stand by for an update on the tag search and recovery. Right now nearing midnight we are burning squares into the dark, foggy ocean in a mile of water to the west of San Clemente Island…listening…
Photos courtesy A. Friedlaender, J. Calambokidis (Cascadia Research)