June 21, 2001
The second half of Leg 1 on the NOAA Ship Henry B. Bigelow has gone fairly smoothly for the acoustics team, with our hydrophone array functioning well now. Despite the weather and high sea states that have made conditions difficult for the visual observers, we were able to make 78 hours of acoustic recordings since our last update on 11 June.
We had more than 90 acoustic detections of marine mammals during this time. Particularly exciting were the first recordings we’ve made of two species: short-snouted spinner dolphins (Stenella clymene) and rough-toothed dolphins (Steno bredanensis). These are not seen or recorded very often by anyone, but of these groups approached our vessel and vocalized when no other species were in the area, so we can be confident that what we saw is what we heard.
In addition, we’ve had many more detections of the commonly encountered species, and we are having fun trying to identify them by their whistles and clicks before the visual team calls down on the radio with a species identification. We are getting better at it, at least for the species with distinctive vocalizations. For example, pilot whales are recognizable by their short, chirpy whistles, and common dolphins by the sheer volume of whistles heard, since they are extremely vocal and are often encountered in large groups. It is always fun to get it right!
Despite our hydrophone array issues at the beginning of the cruise, we have had a successful leg overall, and collected some great data. That’s all from the Leg 1 acoustics team (Joy Stanistreet, Robert Valtierra, and Cara Hotchkin). We wish the next team good luck, calm seas, no hydrophone problems, and lots of animals to listen to!