Needle in a haystack

Back in August we caught our 4th Pacific Sleeper shark. This animal was tagged with a Wildlife Computers mini-PAT (satellite pop-up tag) and then was released right off Caines Head in Resurrection Bay. The mini-PAT had been scheduled to detach itself 90 days after deployment, which was Monday.

And right on schedule, on Monday, the tag started reporting.

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Sleeper Shark SP18-04 with her new tag ready to be released.

When the tag released from our previous shark, the data suggested that over the course of a 10 day window the animal hadn’t moved out of the general Resurrection Bay area where we had caught it.

For SP18-04, after 90 days of data collection the tag first reported from an inaccessible location west of Montague Island by Prince William Sound, over 90 km away! With winter weather settling in over Alaska, we didn’t have high hopes of being able to go all the way out there to find it….but incredibly, just two days later it had drifted west, rounded Cape Res, and snuck into Resurrection Bay, just as sea conditions were improving.

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The green locations are where the tag emerged after it detached from the shark. It then drifted west along the coast all the way up into Resurrection Bay (red dots).

Now it was within reach of a short boat trip!

Those of you that have seen these dark grey, small and unobtrusive tags, realize how much of a wild goose chase for the proverbial needle in the haystack this was, especially for a tag floating at sea (see our previous blog). Undeterred, with the help of many, we went out to track it down. Our team consisted of: Jared, Richard, Renae, Brandon and me from ASLC, and Nicole and Colby Lawrence as captains from Major Marine. Through Tom Tougas, Major Marine kindly made their M/V Freedom available for a run on very short notice (basically this morning).

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Setting off in search of the tag.

We did have an approximate location via the satellite information (Argos / CLS), but the accuracy could only get to to within about ½ mile, and with a 30 min lag. Thankfully, our handy goniometer came to the rescue again (a high tech, $10k RDF for Argos tags) that was expertly set up and operated by Renae and Brandon.

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Brandon setting up the goniometer antenna while Renae manned the computer console. With every transmission from the tag received, the device would provide a bearing to direct the boat.

Following the bearing, we maneuvered the boat up to a patch of flotsam in the middle of Resurrection Bay near Calisto Head. After some careful scanning, we saw a small wire sticking out of the patch of kelp! We quickly swooped up the kelp…

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Jared with the net…is there a tag in there?
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Success!

The excellent RDF work by Renae, and piloting by Nicole placed us right on top of it, where against all odds we were able to recover the tag in less than an hour at sea.

So, we are now two for two in recovering tags from sharks. As we’ve mentioned before, the recovered tags give us access to much more data than the tags can ever transmit. It felt like striking gold – a gold needle in a haystack (or in this case… a kelp-stack?).

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The team with the recovered tag (left to right: Nicole, Richard, Markus, Jared, Renae, Brandon, not pictured: Colby)

Thanks to all who helped make this happen!!!

Stay tuned for more details on the data we have recovered from these first two tags.

 

Written by: Markus Horning, ASLC Science Director

This work is funded by a grant from the North Pacific Research Board. 

All activities pictured and described here were permitted under ADF&G Aquatic Resource Permit #CF-18-041

 

2 thoughts on “Needle in a haystack

  1. Great that you found it so quickly / easily. Looking forward to seeing what the data reveals.

    Any reason not to paint the dark-grey tag bright orange? Like the “black boxes” on aircraft aren’t black but international orange?

    Fund-raising idea: auction off spots for the next such retrievals. Subject to weather, safety concerns, etc, make it transferable in case the winner can’t come maybe their spouse/kid/friend could. High bidders get on a short list, highest bidder gets asked first when a trip comes up (and asked on a later trip if they have to decline) and you go on down the list before each trip to fill the spots.

    I suggested the Pratt Museum auction off tours of their collections (99% of the artifacts aren’t currently on display). It was a popular item to bid on and cost only a little staff time to fulfill.

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  2. Hi David–Great question! In any tagging study we strive to minimize any effects of tagging the animals. We don’t paint the tags because these tags are attached externally on dark grey animals, so there is a concern if we painted the tag bright orange it could act as a ‘dinner bell’ (or I guess in this case dinner target?) for predators to hone in on. Sleeper sharks, as big as they are, are still hunted by offshore killer whales.

    Thanks for the suggestion about the fundraiser as well! So far one tag has come off on schedule and one early. Also, we got really lucky with this one that the tag drifted back to us (instead of drifting off to the middle of the Gulf of Alaska). Throw in the weather and it might be tricky to schedule someone joining us on our recovery missions but we can definitely look into it! It might be a good local fundraiser for folks in town that are a bit more flexible.

    Amy Bishop, ASLC Research Scientist

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