Project news

Sleepy fishing part 3

By Michael Wang, 7th June 2023

A twist of fate

Many months had passed since our last unsuccessful attempt to catch and tag a sleeper shark from the R/V Malolo, and our prospects of locating one continued to look grim.  We hadn’t received any news of new encounters from the local fleet, and with few documented interactions to direct our efforts, any new attempt would be a shot in the dark.  That’s when we got a promising call.

As luck would have it, a commercial fisherman located in central California had heard of our study and had reached out to offer his help.  It turns out that he had recently begun encountering an unusual quantity of sleeper sharks on his bottom-set longline gear, which he used to target sablefish.  When he encounters a shark on the line, he removes the hook and the shark swims free.  We determined that this would be the perfect platform to deploy the remaining tags on sleeper sharks and obtain the depth data we needed for the study.

Then began a feverish race to outfit this new vessel with tags and equipment, as we wanted to make the most of this opportunity while it lasted.  The boat needed a tagging pole so I improvised one that could be adapted to an ordinary broom handle, cutting the base off a plastic squeegee to which I affixed a specialized tag applicator tip with epoxy.  Tags were programmed and rigged with darts, a set of protocols was developed, and everything was boxed up and sent to the fisherman before his next trip.

In a pinch, a little bit of creativity goes a long way.  Here, a plastic squeegee is converted into a tag applicator tip that can be screwed into any broom handle. Photo © Michael Wang

It wasn’t but a few days later that news came of a successful tag deployment from this boat, with another just a few days after that.  By the end of the following month, all of the remaining tags had been put out. Though I wrestled with feelings of disappointment over not having the opportunity to perform the tagging work myself, I was relieved and overjoyed that we’d now have data to work with.  As is often the case in science, opportunities will come from unexpected sources and personal feelings must be put aside to embrace these opportunities head on.  After all, the purpose of this work is to benefit the sharks, not to fuel egos.

Removing the hook after tagging this 2 meter long sleeper shark caught on demersal longline.  We’ll forgive the poor quality of this photo, as this fisherman came to the rescue to put out the tags we needed to complete the study.  Besides, I think the blurry photo also adds to the shark’s mystique. Photo by anonymous | © Michael Wang

The tags we used in this study are advanced satellite tags made by a company called Wildlife Computers.  We had programmed them to record for one month, after which time they “pop off” the shark, floating to the surface to transmit their data to overhead satellites.   All of the tags put out by our volunteer fisherman reported as expected, a cause for relief as we had not been there to oversee the tag placement.  With the data now in hand, we began the task of crunching the numbers, finally opening up windows to the mysterious lives of sleeper sharks off our coast.

A close-up of one of the tags used on sleeper sharks in this study. Photo © Michael Wang

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