Field Notes 8 Aug 2023: Infinite populations of varying density
Some time ago, Fisheries Biologist Matt Kulp (of the Great Smoky Mountains National Park) mentioned to me that they often turn up Desmognathus salamanders when electroshocking for Brook Trout. “Huh,” I said. “Maybe if someone wanted to finally do serious population genetics with those critters, that would be the way to get good samples.” Well, now I have a student (Rebecca Chastain) who wants to do serious population genetics with those critters, and we’ve been partnering with the fish crew this summer to get good samples. The fish crew uses a three-pass depletion protocol to estimate trout densities. Basically, you catch as many fish as you can, set them aside in a holding pen, then do it again. The number of fish caught on the second and third passes should be less than on the first pass, and you can use the changes in those numbers to estimate the total number of fish in the survey area. The fundamental assumption is that each time you go through the survey area, you have the same
