Understanding Leopard Shark Deaths in SF Bay

October 5 2017

Expedition Video

Leopard Sharks have seen a surge of deaths in San Francisco Bay, possibly linked to a pathogen. We're going to use our tools to help gather data.

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October 5 2017

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Preparation Stage

Today David, Kate, and I kayaked from SeaQuest through the anchor-outs, to Strawberry point to scout eel grass, and see how the Trident would function in the shallows of Richardson Bay.


The Three of us took 2 kayaks, a one seater and a two seater (sit on tops) form the Sausalito shoreline with with David Piloting the Trident in the two seater. We stopped at three locations :

37.87903 N - 122.494877 W 37.882132 N - 122.493509 W 37.881799 N - 122.483156 W

Each location the Trident was sent below to inspect Eel Grass and check for any anomalies.

David commented that at several locations he spotted what he thought were Sea Cucumbers

Overall the tide, visibility, and depth made for a pleasant day on the water, but resulted in low visibility.

Findings:

*In shallows the, a slack tide is best for bottom viewing to avoid silt disturbances If you attempting to take samples in strong currents or tides, go 'with' the tide, not against it. *Eel grass can be acquired via the Trident's propeller

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There's already an iNaturalist group that's been created to document citizen science observations. We'll be contributing there, too, and adding underwater images from the OpenROV Trident.


https://www.inaturalist.org/projects/leopard-shark-and-bat-ray-die-off

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There was a report about this issue in Bay Nature a few months ago. All of the reports I've read have mentioned the lack of resources available to study the issue. In Bay Nature:


"The problem, though, has been in figuring out exactly where and when the die-offs were happening, the necessary first step to figuring out why they were happening. “No one’s looking at it consistently,” Okihiro said. “It’s not like we could plot out, there were 2,000 leopard sharks that died in 2011 versus 250 in 2012. There is no one with the job of tabulating leopard shark and bat ray death. We’re doing this all on the fly, on a shoestring.”

Expedition Background

From the NBC News Story:


"As many as 2,000 leopard sharks have mysteriously died in the San Francisco Bay over the past few months. The California Department of Fish and Wildlife says determining the cause is not a priority for the state since the sharks are not threatened or endangered, however, scientists say additional research and resources are crucial since the threat is now believed to be preying on other marine life."

We're going to use the OpenROV Trident to engage citizen scientists in collecting more data about how many sharks are affected.

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