What Kills Sixgill Sharks

[60south]

McGlencoe and I did a dive from the Gardiner boat ramp a couple weeks ago. (Nice, easy dive. Little to no current, good vis, gentle slope -- a great place for training or casual bubble blowing.)

Next to the boat ramp was a rotting sixgill, 5-6ft long. Definitely recognizable, even in the stinky stage of decomposition. We speculated on why it died.

I revisited the site today and the shark had mostly rotted away, leaving behind the likely killer... A plastic mesh bait bag, about 10" on a side.

:-(

[Gdog]

Ouch. That sux. I think we are only beginning to see the ramifications from this disaster. There is some effort to tackle the global problem, but it needs to gain traction at all local levels.
https://www.nytimes.com/2018/09/09/scie ... patch.html

[Penopolypants]

So...humans. :(

Gdog is right, it's good to see some efforts being made, but we have a long way to go.

[ljjames]

Interesting. Thank you so much for posting. After the 4th (known of) stranding/wash up in a couple months I reached out to friend at the aquarium and he recommended that if the scientists can’t get there to do a necropsy that we check for exactly what you found. May I forward your picture on to them?

[60south]

May I forward your picture on to them?

Absolutely.

There was also a baby harbor seal, headless, sloshing in the surf near the shark. No pictures of that. :-(

[ljjames]

Awesomeness! Thank you! Your picture is on its way to WDFW!

If anyone else knows of a sixgill carcass currently accessible on any regional beaches it would be amazing if you could share that information here perhaps? I’ve been chatting with Jeff C. And if we could gather a small tissue sample and freeze it along with as much info as you know about the shark (when it washed up, behavior if locals saw it before it died, etc..) that would be absolutely amazing and maybe we can get them to run the DNA and see what family group the dececdent was a member of. I’ll do the citizen science leg work if need be, and grab the sample if its too gross and stinky, just need to know where

I’m especially curious about the carcass that washed up near the Alki Lighthouse and then got taken back by the high tide before anyone was able to sample it. If anyone hears of it having washed up further down the beach maybe on private property it would be great to know so that we could grab a sample and see if maybe the Elliot Bay family group is returning or it was a roaming Three Tree/Redondo shark.

I’ve been following these strandings with interest all summer and if there is a common cause (mesh crab trap bait bags) it would really help to have any documentation we can to maybe get WDFW to weigh in to have them banned so they can’t hurt any more of our beautiful amazing sharks.

[ljjames]

Likely this type of bag,

http://a.co/d/b2rGulJ

but apparently being the scavengers that they are will, they will poach from recreational traps anytime they can and it sounds like any of the bait bags could be bad news for sub-adult sixgill sharks. This is not a new concern, apparently there was discussion back in 2007ish with WDFW about bait container regulations but they apparently didn’t go anywhere. If I hear anything tomorrow re: WDFW response to the image I’ll share.

Thank you again 60south for documenting this!!!

[ljjames]

Reached out to a friend at the Coastal Watershed Institute in Port Angeles and she was able to send a couple interns over to the boat launch and they collected DNA sample and also the mesh bag for further investigation. Will be meeting them and getting the samples handed off to Seattle Aquarium staff post haste. It will be so intersting to see if we can find out what family group the decedent was a member of.

Thank you again for posting!

[60south]

Excellent! Glad they found the spot.