Operation Sleeper Keeper

“Straight ahead!” Dr. Horning called out to the crew, taking his binoculars down and smiling. We had been gently bobbing south down Resurrection Bay for the last 40min, listening for the soft beep of the goniometer to confirm we were getting closer to our target—a miniPAT tag that had detached from a Pacific Sleeper Shark we’d tagged earlier this summer. Jake scooped the small device out of the water and we all exchanged a round of high-fives.

If that had been the end of the day, we would have considered it a well-earned success; but that victory paled in comparison to what Taylor shouted out an hour later, as we hauled in our third line:

“It’s a shark!

IT’S A VERY SMALL SHARK!!!”

After nearly 30 days of fishing since 2018, and 12 sharks caught that were between 8-12ft long– we all crowded along the port side gunnels to see what Taylor was talking about. There, slowly swimming at the surface was a little one—just over 5.5ft long by our rough estimate—which meant that this one, SP19-04, was small enough for our main study back at the Alaska SeaLife Center!!

Instead of taking out the usual tags and blood sampling supplies we use for large sharks we can’t bring back to the ASLC, we pulled out pumps to fill up the Transport-Experimental-Chamber (or TEC) with seawater. One major design of our study was to minimize the amount of time the shark was out of water, preventing it altogether if possible. Although SP19-04 was easily smaller than all the other sharks we’d worked with, it probably still weighed about 60-90 kgs (or 110-200 lbs). So, our team readied a stretcher that would hold the shark as well as water, gently maneuvered it under the shark’s body and in one fluid motion transferred SP19-04 into the TEC. Now with the shark a little easier to observe than over the side of the boat, we determined that it was a male shark. We monitored his general condition, his breathing (or gilling), and behavior.

We caught this shark just west of 4^th of July Beach in Seward at a depth of approximately 300 m (900 ft)! The close proximity to town meant our transport back across the Bay was short—which was good because we had to motor slowly to minimize sloshing in the TEC. Once we got to the harbor, we trailered the boat with the TEC still aboard, and drove it back to the center. While we were still out in the Bay, Jared had radioed the center that it was “operation sleeper keeper” and the team back at the ASLC mobilized to get everything ready for his arrival. After one more quick stretcher trip, the little guy was introduced into our deepest and largest outdoor tank, modified with a pool cover over half the tank to provide him some dark refuge.

It has now been 10 days since we first saw SP19-04 come up from the depths.  He seems to have adjusted well, as best as we can tell considering we know very little about this species! We can theoretically maintain him in this space for up to 6 weeks if his condition stays stable, after which he will be released back into the Bay. We may however decide to release this first animal sooner than 6 weeks. Upon release he will be monitored with tags to assess if there are any abnormal behaviors, and to learn more about where he goes and what he does in the wild. This model of temporary controlled access allows us the opportunity to conduct a few planned experiments.

We will go more into the details on the next steps of this research—the question, the methods, and the problem solving that go into studying the metabolic rate of Pacific sleeper sharks–in the next post. So be sure to subscribe by email so you don’t miss out on any part of this story!

Written by: Dr. Amy Bishop

This project is led by Dr. Markus Horning (ASLC) and Dr. Chris Lowe (California State University, Long Beach); together with graduate student Taylor Smith (CSULB), and Co-Investigators, Dr. Amy Bishop, Richard Hocking, and Jared Guthridge (ASLC).

This project is funded by the North Pacific Research Board (NPRB). The project is permitted by ASLC’s institutional ethics committee (AUP # R19-05-05) and by the Alaska Department of Fish & Game (CF-19-085).