Froggies! How fun. It's been a couple of years since I've contributed my compelling and keen observations on them. I'll just throw in a few points 'cause, as has been commented on, there's a zillion threads here on the subject. Still, looks like some new folks here. So:
* The Yellow Legged Frog doesn't go 'ribbet'. It's rare to hear one and, if you do, it's a high pitched squeak. Endangered and listed. Required by law to be protected. The ones that go 'ribbet' are the Pacific Chorus Frog, formerly the Pacific Tree Frog. Tiny, but loud. Black eyestripe and about the size of your thumb. Not at all endangered.
* Fish were not native to ANY high Sierra lake above about 8,500 feet. When the glaciers came through, if there were any, they were wiped out and couldn't make it beyond waterfalls and steep cascade barriers. All fish now in the High Sierra were introduced starting in about the 1890s by packers and, much later, by California Fish and Game.
* One of the primary purposes of National Parks is to protect and preserve native critters and plants and their ecosystems. Froggies are native, fish in the High Sierra aren't.
* That said, the fish will continue to thrive in the majority (!) of High Sierra Lakes. There's really only a few basins suitable for fish removal and restoration of yellow legged frogs. The idea is not to restore an isolated lake here or there, but a basin such that populations can intermingle, moving from lake to lake.In my experience (and, granted, I've been gone from Sequoia for 4 years) few of the lakes slated for fish removal had decent fishing. Most averaged probably less that 10" and were overcrowded because of limited spawning areas and finite food supply. Only a few basins meet the criteria for restoration (one of the primary ones is having some sort of barrier like a waterfall to keep the fish from coming back and, at the same time, be suitable habitat for frogs).
* I'm always confused at the "ah ha! We've got you now" reaction to the relationship of Chytrid and fish to frog mortality. The reaction seems to be that if one is true, the other can't be, which is wrong. Both contribute. The original problem (up to the 90s) was fish. The yellow legged frog (and, incidentally, I'm using old nomenclature. There's now three species. The dividing line of two is Mather Pass) never evolved with fish and so have no survival defenses. When threatened, they jump into the water where, if there's fish, they're eaten. Incidentally, the great memories of my youth hiking in the 60s is going along almost any lake margin with hundreds of frogs leaping into the water ahead of me. After about 1990, that was rare. They were gone from probably 80%+ of their former range. About that time (90s) the danger was recognized by biologists (notably Vance Vreedenburg, then a PhD student at Berkeley) who fairly quickly identified fish as the problem. Working in 60 Lakes Basin, he and his crew ran a net down the middle of the first lake you come to entering the basin. They netted all the fish on one side, not on the other. Within a week or two, frogs were back in the non-fish side and doing quite well. An elegant and compelling demonstration.
The need for populations throughout a basin are critical. If something hits one lake, migration is always occurring and froggies colonize from another. If there's only one lake left with frogs, they're in trouble. That's exactly what happened throughout the Sierra. Most basins were down to one lake where fish, for one reason or another, didn't occur.
* The NPS authorized continuing the experiment throughout that basin and Yosemite started doing the same. It was spectacularly successful. The frogs were saved! Yay!
* But, bad news, at the very same time (late 90s) Chytrid was appearing on the west slope of the Sierra and moving up several hundred vertical each year. It has already probably extirpated most foothill populations of the red legged frog and, within a few years, was killing alpine populations of the YLF.
* So, the next problem became what to do about Chytrid. Meanwhile, the NPS continued with their restoration program in the easy basins while, worldwide, biologists began working frantically on Chytrid. It was/is wiping out frogs everywhere. In Sequoia Kings, I think every surviving YLF population occurs where fish had been netted and frogs restored. A bunch of different methods are being tried: breeding resistant frogs in labs, then taking them to the Sierra; inoculating them in lakes; coating them with various chemical to kill the chytrid.... & etc. (I don't keep up as well as I should). They are having some success. As pointed out, some populations have developed at least partial immunity but (!) this can only occur when you have a critical population number such that you can get immunity in a significant percentage to form a breeding group and survive AND if their habitat is spread throughout a basin to take advantage of dispersal.
But, really, what this comes down to is what importance people put on having a place on the earth that attempts, however imperfectly, to maintain ecosystems as they have existed for tens of thousands of years vs. fully protecting a non-native species who, in addition to eating frogs also take out huge number of insects with major effects on lake and stream ecosystems. Some early studies show a return of a number of birds because of the rebounding insect populations once fish disappear.
This ongoing effort is also an incredible example of what happens when the results of field science discoveries are applied to mitigate the loss of a species. We've seen this in spectacular recovery efforts off Bald Eagles, Peregrine falcons and Brown Pelicans with removal of DDT from the food chain. Condors, too, have been brought back from the brink of extinction with an aggressive and science based breeding and rearing program. Bighorn sheep, too, are showing great improvement in range and population as a result of protection efforts. This is all to say that there are great examples that "letting nature take it's course" are wrong when an effort is made on behalf of the endangered critter.
Thank you all for coming. You've been terrific and attentive!