J pod calls, but doesn’t click?

It could just be the springtime kelp rubbing on the hydrophone causing a lot of noise, but I noticed today when analyzing a short 20-minute bout of SRKW signals that there were plenty of calls audible, but no echolocation clicks. Yet, just a few minutes later, echolocation clicks were heard on the Lime Kiln hydrophone livestream on YouTube. This may be another example of how J pod can transit a hydrophone location silently, calling/clicking/whistling continuously, or intermittently emitting only calls or only clicks (the latter of which can sometimes can be seen in a spectrogram, but not heard in real time, especially by old human ears that can miss the high frequencies).

Another interesting thing about this bioacoustic event is that neither humans nor machines detected it in real time. Perhaps our guard was down since they had last been sighted southbound in Rosario Strait yesterday and some of us were expecting them to visit Puget Sound or head back out the the outer coast? Or maybe the loud rubbing of the kelp recently both annoyed human listeners from being vigilant and confused the OrcaHello machine learning model with only a low signal:noise data stream? In any case, there were no new reports from human Orcasound listeners or on the OrcaHello detection candidate page.

Upon review of the recorded livestream, triggered by the sightings shared through the Whale Sightings in the San Juans Facebook page, at around 7:57 this morning, a single S04 audible through a lot of kelp rubbing noise on the Orcasound Lab hydrophone. Then S01s, a few S02s, and an S44 were audible from 8:00-8:04. After no signals for about 10 minutes, there were a few more calls for a couple minutes around 8:13 that could be heard through some tonal boat noise. So assuming they came in from the north, that sequence could match the two groups that Sylvie Gareau observed off the County Park…

The open data recording of the event is now available here in mp3 or ogg format — https://orcasound.net/data/product/biophony/SRKW/bouts/240522-0630-OS-J-SB

If anyone else wants to analyze in the free and open source Audacity program, there is also a preliminary label track that can be imported. I’d particularly value any comments about the calls and signals that I marked as “??” …

A final thought about this morning is that as J pod was southbound in Haro, a triplet of vessels was northbound: a tug towing a gravel barge, a bulk cement carrier, and an oil tanker. The three ships effectively/accidentally formed a convoy, with the tug apparently slowing down or at least moving close inshore where it became visible from the perspective of the Lime Kiln web cam, just as the J pod leaders were passing the Park echolocating along the way. One livestream listener wondered if the tug was slowing for the whales and noted that the noise from the vessel(s) had decreased.

Here are a few screenshots from the M2 system, the webcam, and vesselfinder.com for the record:

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