SoCal Endangered species herping, part 1

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Sam Sweet
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SoCal Endangered species herping, part 1

Post by Sam Sweet » July 15th, 2010, 11:43 pm

Amphibian breeding season is winding down here, so perhaps it’s time for some photos and stories, tiger salamanders first (others to follow). It was a so-so year for the isolated Santa Barbara population of Ambystoma californiense. While rainfall was above average and the ponds are in good shape, the only decent rainfall that continued after dark came in late February, so the salamanders bred late and their larvae were always smaller than their favorite prey of tadpoles.

Tiger salamander ponds around here are not usually garden spots, especially where there are cattle. There’s far too much mud for wading, sloshing around in there risks injuring larvae, and sampling nets fill up with goo. We’ve solved those issues with a trawl on skis and a couple hundred feet of rope:

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This works a treat, and lets us sample the foulest of ponds:

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If larvae are reasonably common, one pull is all you need:

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Larval and juvenile tiger salamanders from the Santa Barbara isolate are pretty odd in comparison to those farther north in the range. They can get quite large before metamorphosing (5-7” TL, occasionally larger) and change from their original silvery green to olive or tan with dark spots, whereas larvae elsewhere tend to get darker with a few pale spots (and usually metamorphose at about 3" TL). We also get the occasional “cannibal morph” animal, not seen elsewhere in A. californiense, as far as I know.

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Likewise, the recent metamorphs are pretty strange, for those who have seen Ambystoma californiense elsewhere. These guys do darken up with age, and by the time they’re mature they look pretty much like californiense from elsewhere, believe it or not.

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Remember when cameras used to have focal lengths?

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I’ll anticipate two issues: (a) yes, we have permits, and (b) some of the odd features in this part of the Santa Barbara range raise the issue of hybridization with nonnative Ambystoma mavortium. Brad Shaffer’s lab has run both mitochondrial and nuclear DNA profiles on samples from nearly all of these ponds, and they come out having no exotic genes. These distinctive features are part of the reason that USFWS has put a high priority on maintaining the viability of the Santa Barbara isolate.

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Chad M. Lane
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Re: SoCal Endangered species herping, part 1

Post by Chad M. Lane » July 16th, 2010, 12:15 am

Great report Sam. I enjoyed it very much. That resent metamorph is strange.



Thanks,
Chad

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jonathan
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Re: SoCal Endangered species herping, part 1

Post by jonathan » July 16th, 2010, 5:05 am

Nice post!

Until this year I'd only seen 4 endangered herp species in my life. This year alone I've seen 5, with a 6th likely coming this month. But those Cali Tigers weren't one of them.

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dezertwerx
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Re: SoCal Endangered species herping, part 1

Post by dezertwerx » July 16th, 2010, 6:56 am

Very cool post...

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Fundad
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Re: SoCal Endangered species herping, part 1

Post by Fundad » July 16th, 2010, 10:22 am

:shock:

Thanks Sam, your posts always Rock..

It's good to know those manders are in Good hands with you.. :thumb: :beer:

Fundad

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Kerry Nelson
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Re: SoCal Endangered species herping, part 1

Post by Kerry Nelson » July 16th, 2010, 10:54 am

That trawl design is brilliant!

It still baffles me how tigers in some areas seem to get by in the crappiest of habitats, but seem very sensitive to certain disturbances.

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Re: SoCal Endangered species herping, part 1

Post by justinm » July 16th, 2010, 12:01 pm

Your net on skis has me brimming with ideas, that thing is brilliant.

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Carl Koch
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Re: SoCal Endangered species herping, part 1

Post by Carl Koch » July 16th, 2010, 10:39 pm

Great report on an amazing creature! Love the pic of the recent metamorph.

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Sam Sweet
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Re: SoCal Endangered species herping, part 1

Post by Sam Sweet » July 17th, 2010, 2:36 pm

The ski trawl has made a big difference in a variety of situations. I don't like to tramp around in ponds where I can avoid it (mostly to cut down on churning up bottom communities), and many ponds are simply too deep or too muddy to wade, and rigging a towable seine is a hassle and often overkill. We used to use shad nets (metal ring with a net bag and 4 lines) which are light, and with a bit of practice can be thrown 12-15 yards, but they had a tendency to dig in wherever the bottom slope changes and give you a cubic yard of mud to haul out and sort through.

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You can't throw the ski trawl and it's a pain to carry through brush, but it does hold the bottom and will go through moderately thick vegetation with a couple fellas on the rope. We use 3/8" mesh to cut down on clogging and also to let smaller critters pass through. It wouldn't work around logs, branches, or cypress knees, or where ponds tend to get shopping carts and stolen bicycles in them, but it's the ticket for many situations where you need an efficient way to see who's in a pond.

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cgparis
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Re: SoCal Endangered species herping, part 1

Post by cgparis » July 19th, 2010, 10:31 am

Pretty cool Sam. It's nice to see the process sometimes and not just the animals. By the way I know what you mean by muddy trawls. Muddy trawls are my life now.

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Schell
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Re: SoCal Endangered species herping, part 1

Post by Schell » July 19th, 2010, 11:40 am

That is a very interesting contraption Sam. We usually don waders and a seine and muck-it-up. I totally agree about not wanting to get into the ponds from a disturbance and pathogen perspective. This looks much more compelling than using a seine. Is this home made or is it something that is commercially available. PM me if you'd like.

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chris_mcmartin
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Re: SoCal Endangered species herping, part 1

Post by chris_mcmartin » July 19th, 2010, 11:58 am

I'm very impressed with the ski trawler.
cgparis wrote:By the way I know what you mean by muddy trawls.
And as we all know, "The Muddy Trawls" would be a great band name. :thumb:

cgparis
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Re: SoCal Endangered species herping, part 1

Post by cgparis » July 19th, 2010, 12:04 pm

Yeah I've seen them. They opened for The Torn Seines.

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Sam Sweet
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Re: SoCal Endangered species herping, part 1

Post by Sam Sweet » July 19th, 2010, 5:26 pm

The trawl frames are 3/4" square tube stock, welded, with plates welded on the bottom to which the skis are bolted. Those are made from 1/4" pvc sheet bent to shape with a heat gun. We had the nets made to order (Memphis Net and Twine), but found we had to be real explicit with them about size and where the opening is -- they found several ways to interpret simple diagrams and measurements. Ski trawls work best with lines tied to both lower corners and a single line off the middle of the top frame, converging onto a ring for the tow rope. Our frames are 32x20" and the net is 4' deep, but you could certainly go larger (even to 3x6') w/o creating something that's too hard to pull, as long as the mesh size isn't decreased.

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