SEA Currents: Robert C. Seamans
October 27, 2017
Listening for Whales off Tonga
25˚03.0’S x 176˚10.6’E
Ship’s Heading & Speed
185˚ going 4.9 knots under the four lowers and tops’l.
Force 4 ExS winds with 6 foot seas. Cloudy with scattered rain, 24˚C
We have been deploying a hydrophone each morning during our science station to hopefully pick up on whale song along our cruise track. Humpback whales breed and calve in Tongan waters each year and we’ve seen them blow, breach, and flap around periodically.
One question we’ve faced while listening to the hydrophone is, what noises are generated from the boat and what sounds are actually from the whales?
Today, during our hydrophone, the science team was able to isolate vessel noises thanks to support from Ted and Mike, our engineers on board.
Over the course of our 30-minute hydrophone deployment, the Robert C. Seamans went black ship. The generators, main breaker, ventilation, water makers, refrigeration, our depth sounder CHIRP, and our Acoustic Doppler Current Profiler (ADCP) were all turned off and then one by one systematically turned back on. Amy was listening on the headphones and just kept remarking on how loud we actually are after hearing how quiet it was with nothing running. Just for good measure, we sent down Josh to the engine room to stomp around to see if we could isolate those sounds as well. We could. We could even hear the opening and closing of the watertight doors in the engine room and maybe even the head flushing.
It’ll be interesting to analyze the Seamans’ soundscape and compare it to the audio of haunting whale song collected in Tongan waters. Ali, Alessandra, and Noah’s oceanography project delves deeper into this question and I’m intrigued to find out what they discover.
As sailors and ocean scientists, we use our eyes a lot to analyze clouds and waves and to see trends in biodiversity and nutrient amounts. I personally have a new found fascination on the different sounds that surround us in the South Pacific.