SoundTrap ST600 click detector for delphinids and porpoises

Question

We are deploying a number of SoundTrap ST600s and are currently trying to determine the best parameters for the click detector. We are most likely to encounter Harbour Porpoise and Bottlenose Dolphins, and potentially Risso's and other dolphins. The parameters are:

• Threshold: we are thinking of using 10 dB to be conservative.
• Integration time: the ST user guide suggests 70 μs for most delphinids and 150-300 μs for porpoises and NBHF delphinids.
• Blanking time: currently using the default 1000 μs.
• Snippet pre- and post-trigger durations: we have been using the default 750 μs for each. The ST user guide states "The snippet starts pre-trigger seconds before the detection and ends post-trigger seconds after the detection." Does this mean the post-trigger snippet begins after the start or end of the detection? I.e. should we be using a longer post-trigger snippet length to account for the signal duration?

I wondered if anyone has used the ST600 click detector for similar species and has recommendations.

I also notice that the endurance calculator doesn't factor in the click detector and wondered if anyone has any advice about energy usage when the click detector is running.

Answer 1

For our project, we also expected both dolphins and porpoises, so we set the integration time to an intermediate value of 100μs. We raised the threshold to 12dB because it was quite a noisy environment, but indeed 10dB will be more conservative. We kept all the other settings as default. Regarding the integration time, we choose a middle value following recommendation from the manual, but didn't assess how exactly it worked compared to other settings (yet!).

On the endurance, we were also worried about the space the click detections would take in the SoundTrap (HF500), so we added memory cards, but that caused us more problems (see an answer to this post)... In the end we used the default internal memory and were still able to get 5+ months on a 1/3 duty cycle, so it didn't seem to use up so much memory.

Hope this helps!

Answer 2

Similarly to Morgane, during our recent long-term PAM project on the Scottish west coast we used an integration time of 100μs and 12 dB as the threshold, we raised the blanking time slightly to 2000μs and left the pre/post trigger at 750μs. These settings were aimed at finding a compromise between being able to detect dolphins and porpoises. We arrived at these setting by doing some tests with the Porpoise Alert (PAL) device before deployment. We had good success with these settings, detecting both porpoises and various dolphin species successfully. However, more tests of these settings in the field and in comparison to full bandwidth recoridngs would be very useful, indeed. During our project we achieved about 3 months deployment time for the Strap 300HF with battery pack, when recording at at duty cycle of 20/40 and 96 kHz sampling rate and the click detector turned on.

Answer 3

We use them for clicky things too, mostly porpoise though we have gotten killer whales as well, so pretty broad spectrum.

We go with the default manufacturer settings and, like the C-PODs it's a pretty high recall detection system. So it's likely to catch most things. That said TWICE the manufacture has sent us instruments with faulty settings that needed to be cleared before we put them in the water. We missed it the first time and it crapped out the entire recording system. So...be careful of that :). I'll see if I can dig them up from our reports if that would be helpful!