How real scientists are working to save the whales.
Owning to the overwhelming popularity of the post I did on birds, I was going to do another avian post. However, two weeks ago I was given the opportunity to take part in some really nifty research taking place on the west coast of Scotland. I'm so excited to share it with you all so, sadly, the birds will have to wait.
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| Visual and Acoustic Surveys-Photo credit Simone Prentice |
For once, words fail me to describe the trip. From a personal standpoint, it was amazing but I will spare you my balthering on about how lovely everything was (with a few exceptions pertaining to american /British English-basically they call everything a pudding, mangetout is a vegetable not a command and pants are not pants).
So, for the last 8 days I have been participating in visual and acoustic surveys on the west coast of Scotland with the Hebrides Whale and Dolphin Trust (HWDT). HWDT has surveyed much of the west coast of Scotland over the past 12 years in order to monitor long-term changes in marine mammal presence and abundance. In this endeavor they have been extremely successful, publishing numerous reports and peer-reviewed articles on the local fauna (biologist word for animals, we can be jerks too).
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| Survey route- Kerry Froud |
The complicated coastline of western Scotland provides a challenging acoustic environment for war games including mine detection. Unfortunately, as anyone with an interest in marine mammals knows, the naval sonar used to detect said mines can have catastrophic effects on marine mammals. This is why HWDT is conducting visual and acoustic surveys, in order to try to understand what, if any, effect these exercises are having on the local ecology.
The second goal of this trip, and the reason for my involvement, was to test out the "soundtrap" acoustic recorder. Soundtraps are a sexy new toy for recording underwater noise as and biological sounds. They can record very high pitched sounds including clicks produced by harbour porpoises (>130kHz) and can be towed behind a boat or placed in a stationary deployment.
The Soundtrap was loaned to HWDT by SMRU as part of an ongoing collaboration between the two institutes.
One of cool things about the soundtrap is that it's small size (~size of a Coke can) allows it to be deployed in numerous ways. The first deployment conviguration we tried was to tow it behind the boat then download all the data at the end of the day. The second configuration involved attaching the unit to a buoy and letting it drift all night in the vicinity of the warships. This configuration involved bamboo sticks, duct tape, a large pink float, more duct tape, a plastic lunchbox, duct tape, zip ties, a black flag which I was convinced was going to be mistaken for a terrorism banner, duct tape and a note begging anyone who picks the unit up to return it to HWDT. We then tied the soundtrap to the bottom of all this flotsam. Finally, we fitted two off-the-shelf GPS devices to the top of the rig so we could find it in the morning.
I wish I could report to you that, from the one trip, we could clearly tell than local cetaceans (whales and dolphins) either did or did not react strongly to the presence of the warships. Unfortunately that's not the way most science works. While we did observe and record both animal calls and suspected naval sonar, we cannot conclusively tell what the effects may have been just yet.
I will, however, point out some anecdotal observations.
1. The first large whale sighting of the trip was just south of the area of naval exercises. We observed one Minke whale that looked like it was in a major rush and heading away from the area where the naval vessels were. We did not record any sonar at the time. It is impossible to say whether the whale was moving away from the boats, heard a particularly attractive mate or knew of a great spot for herring. Or maybe the naval sonar made it hard of herring (guffaw guffaw guffaw fish pun)
2. While we were in the general proximity of the war ships we were fortunate enough to encounter common dolphins who were bow-riding the Silurian. I can't describe to you how cool it is to be within a meter of wild dolphins and hear them whistling through the water in real-time.
The Soundtrap was loaned to HWDT by SMRU as part of an ongoing collaboration between the two institutes.
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| Soundtrap attached to a buoy for overnight deployment -Photo credit Jane LovelypersonwhoslastnameIforget |
One of cool things about the soundtrap is that it's small size (~size of a Coke can) allows it to be deployed in numerous ways. The first deployment conviguration we tried was to tow it behind the boat then download all the data at the end of the day. The second configuration involved attaching the unit to a buoy and letting it drift all night in the vicinity of the warships. This configuration involved bamboo sticks, duct tape, a large pink float, more duct tape, a plastic lunchbox, duct tape, zip ties, a black flag which I was convinced was going to be mistaken for a terrorism banner, duct tape and a note begging anyone who picks the unit up to return it to HWDT. We then tied the soundtrap to the bottom of all this flotsam. Finally, we fitted two off-the-shelf GPS devices to the top of the rig so we could find it in the morning.
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| Soundtrap attached to a surface buoy. Real science often involves a disturbing amount of duct tape. Photo credit Kerry Froud |
I wish I could report to you that, from the one trip, we could clearly tell than local cetaceans (whales and dolphins) either did or did not react strongly to the presence of the warships. Unfortunately that's not the way most science works. While we did observe and record both animal calls and suspected naval sonar, we cannot conclusively tell what the effects may have been just yet.
 |
| Soundtrap with unknown warship in the background note duct-tape is still holding strong-Photo credit Kerry Froud |
I will, however, point out some anecdotal observations.
1. The first large whale sighting of the trip was just south of the area of naval exercises. We observed one Minke whale that looked like it was in a major rush and heading away from the area where the naval vessels were. We did not record any sonar at the time. It is impossible to say whether the whale was moving away from the boats, heard a particularly attractive mate or knew of a great spot for herring. Or maybe the naval sonar made it hard of herring (guffaw guffaw guffaw fish pun)
2. While we were in the general proximity of the war ships we were fortunate enough to encounter common dolphins who were bow-riding the Silurian. I can't describe to you how cool it is to be within a meter of wild dolphins and hear them whistling through the water in real-time.
Video captured by Laurel Brenton. At 9 seconds you can hear a dolphin whistling. So cool!
3. We were able to record common dolphin whistles at the same time as navy sonar. Just scanning through the data it looks like they may, possibly, call less at the exact moment the sonar device is going off. But, on the other hand their behavior (bow-riding) didn't indicate the least bit of disturbance by the presence of naval sonar.
4. Even though there appeared to be a slight correlation between the number of whistles and the amplitude (volume) of the sonar, it's important to note that the sonar is lower frequency than the whistles.
Why are the relative frequencies (whistles vs. sonar) worth mentioning? Because, like humans, dolphins have a set range of frequencies that they can hear and are sensitive to. Just like we can feel low frequencies resonating in our chest at rock concerts but can't necessarily hear everything, Many dolphins have the greatest hearing sensitivity in the 40-160 kHz. That doesn't mean that the dolphins can't hear as well in the 5 kHz range (where the sonar is) but it may indicate that loud noises in those ranges may not bother them as much. Other animals such as Minke whales, are much more sensitive to lower frequencies and therefore may have a stronger reaction to sonar at those frequencies.
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| Navy sonar recorded while dolphins were bow-riding. Data from HWDT and SMRU |
4. Even though there appeared to be a slight correlation between the number of whistles and the amplitude (volume) of the sonar, it's important to note that the sonar is lower frequency than the whistles.
Why are the relative frequencies (whistles vs. sonar) worth mentioning? Because, like humans, dolphins have a set range of frequencies that they can hear and are sensitive to. Just like we can feel low frequencies resonating in our chest at rock concerts but can't necessarily hear everything, Many dolphins have the greatest hearing sensitivity in the 40-160 kHz. That doesn't mean that the dolphins can't hear as well in the 5 kHz range (where the sonar is) but it may indicate that loud noises in those ranges may not bother them as much. Other animals such as Minke whales, are much more sensitive to lower frequencies and therefore may have a stronger reaction to sonar at those frequencies.
So, big results? Naval sonar kills dolphins? Dolphins don't give a hoot about naval sonar if there's something more interesting around? As they say in the south, hard tellin' not knowing. The not knowing bit is why I and other conservationists/researchers sacrifice time money and social skills to be out there where the action is to best understand what the big issues are for these animals.
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| Some idiot up the mast-Photo credit Laurel Brenton |
Thanks for reading!
*Research cruise- it's like a holiday cruise only you work your butt off surveying, compiling data, and maintaining equipment from dawn to dusk as well as doing chores related to living in highly cramped conditions.
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