A few months ago, I went to Alaska to help drop very expensive science to the bottom of the ocean. Last week, I went back to Alaska to try and pick it back up. “Try” is the operative word here, because often times, when you drop equipment into the ocean, you have no idea if you’ll ever see it again…
To catch up on some background info for this project, you can read my previous blog post. But to summarize it really quickly, grad student Michelle Fournet (OSU) and I are looking at the effects of vessel noise on humpback whale and harbor seal vocalizations, respectively. This project is all taking place in Glacier Bay National Park, Alaska. At the end of May, we deployed four hydrophones to monitor the underwater soundscape.
I flew in to Gustavus, Alaska on a Tuesday evening with Michelle and our friend/field assistant/resident electrician David. It was a beautiful flight.
|This flight is always a treat. (Photo: L. Matthews)|
We spent all day Wednesday prepping for the recovery of our four little hydrophone babies. Eight foot long hydrophone babies. 100-pound hydrophone babies. Hydrophone babies full of five months worth of acoustic recordings. Hydrophone babies that hold the keys to both mine and Michelle’s dissertations.
|The aforementioned hydrophone babies, pre-deployment. (Photo: L. Matthews)|
In theory, we knew exactly what was going to happen during the recovery. Each hydrophone is snuggly situated in an aluminum cage. Each cage is connected to an acoustic release via 500 ft. of line. The acoustic release is key – that’s how we get our hydrophones back. When the time comes to retrieve them, we send an acoustic signal from the boat to the release. This acoustic signal tells the release to float to the surface. Then, once the release is spotted, we can pull it on deck, connect the attached line to a crane, and reel up the 500 ft. of line and the accompanying hydrophone. Michelle, David, and I talked through this recovery protocol with Chris Gabriele, a biologist in Glacier Bay National Park, at least 30 times. We were still nervous to see how it all played out. You see, sometimes, when you send the acoustic signal to the release, it doesn’t work. Nothing floats to the surface. The hydrophone remains on the ocean floor, patiently waiting.
We met up with Paul and John Martin of the M/V Lite Weight (our recovery vessel) early on Thursday morning. We arrived at our first hydrophone location about an hour later. We sent the acoustic signal to the release. And then we waited. All eyes on deck scanned the water’s surface for any sign of our buoyant yellow friend.
It was about a minute later when the release was spotted! Celebration commenced. Hugs, laughter, a solitary joyful tear; we were all so pleased that it had worked. We turned our attention back to the water only to realize that the release was gone. GONE! The tides had pulled it below the surface. Well, now what?
|So much water. No releases to be seen. (Photo: D. Culp)|
Do we wait for the tides to calm down? Do we put out grappling hooks to try and snag it? Do we stare dismally at the water until it magically reappears? The answer is D, all of the above.
The release was re-spotted about 45 minutes later and pulled on deck. We still don't know exactly why or how it returned to the surface. It's possible that the tides let up a bit. It's also possible that there were some issues with the line and it needed some extra time to sort itself out. Whatever the case may be, we will definitely be taking extra precautions next year to ensure that this isn't a recurring problem.
|Acoustic release fresh from the ocean! (Photo: L. Matthews)|
The crew of the Lite Weight worked their magic and before we knew it, the hydrophone and its cage were safely on deck. Success!
|Yaaaaaaay!!! (Video: L. Matthews)|
I’ll keep this short and just tell you that despite temporarily losing 3 of our 4 releases to the whims of the tides, we had four hydrophones on the deck of the boat by 1pm. It was an amazing feeling! All of that science we dropped off five months ago was finally back!
|The recovery team minus David (Photo: D. Culp)|
The tides were a challenge – the releases weren’t supposed to disappear back underwater. But we pulled it together and overall had a very successful recovery. This, however, was not the end of our troubles. There was a suite of technical issues that arose as we prepped the hydrophones to be shipped back to Oregon for data processing. These technical issues were also challenging and unforeseen. Luckily, the team rallied and managed to solve every challenge that came our way. In the end, we summarized the trip by saying, “things went wrong, they weren’t our fault, but we fixed them anyway." It was a solid week of science.
FUN SCIENCE FACT #42: The highest tides in the world can be found in the Bay of Fundy, Canada, which separates New Brunswick from Nova Scotia. The difference between high and low tide in the Bay is upwards of 16m! That's taller than a 3-story building! Glad we weren't trying to recover hydrophones in that part of the ocean...
|Tides in the Bay of Fundy (Photo: Steve Brown)|