Testing the Utility of an Adaptive Cluster Sampling Method for Monitoring a Rare and Imperiled Darter

Abstract

Adaptive cluster sampling (ACS) designs were tested against simple random sampling (SRS) designs to determine whether ACS designs were more suitable sampling protocols for monitoring rare fish species. To test the utility of these designs, baseline data on the tuxedo darter Etheostoma lemniscatum (a rare, federally endangered fish) were collected at three sites on the Big South Fork of the Cumberland River and used in computer simulation of ACS designs. Based on the simulation models, five ACS designs were chosen and tested at 13 potential monitoring sites. In terms of efficiency, ACS designs performed better than SRS designs, providing estimates with smaller standard errors. Adaptive cluster sampling design efficiency increased with effort; therefore, the two goals-minimizing effort and maximizing accuracy-are incompatible. Because it had less error, an inverse ACS design was recommended, although it required more sampling effort than other designs. Factors possibly affecting overall design performance include the sample size, neighborhood configuration, and habitat complexity of sampling sites. This study was the first to implement ACS for rare and endangered stream-dwelling fishes and provided methodologies for pilot testing and selecting appropriate ACS designs for an imperiled fish species. Adaptive cluster sampling designs are best suited for monitoring imperiled fishes that exhibit a more-clustered spatial distribution. Population estimates from ACS designs using underwater observation provide quantitative data from standardized protocols that are applicable to long-term monitoring of imperiled fishes.Current extinction rates are estimated to be greater than background extinction rates (May et al. 1995), and freshwater fauna are disappearing from ecosystems at an alarming rate (Ricciardi and Rasmussen 1999). Furthermore, a large percentage of imperiled species in Tennessee are small, native minnows and darters (Etnier and Starnes 1993), which are currently threatened by impoundment, various land use practices (i.e., agriculture, urbanization, and deforestation), invasive species, poor water quality, and overharvesting, in the case of larger species (Richter et al. 1997). Sampling designs that reduce variation within estimates of rare and endangered species can pro-

Small fish, large river: Surprisingly minimal genetic structure in a dispersal‐limited, habitat specialist fish

“…made a similar observation in highly endemic sulfide spring fishes, suggesting that inbreeding is not an inevitability of bottlenecked populations, especially in species, like E. lemniscatum, that have evolved in small geographic areas Eisenhour and Burr (2000). estimated a census size (N c ) of 300-600 individuals, and a total of 200 and 100 individuals were estimated for the species in 2008 and 2009, respectively(Davis, 2010;Davis, Cook, & Smith, 2011). Our N e estimate (N e = 497, 95% CI = 315-1,060) and the total number of individuals observed in the course of our study (N OBS = 271;…”

“…Eisenhour and Burr () estimated a census size ( N c ) of 300–600 individuals, and a total of 200 and 100 individuals were estimated for the species in 2008 and 2009, respectively (Davis, ; Davis, Cook, & Smith, ). Our N e estimate ( N e = 497, 95% CI = 315–1,060) and the total number of individuals observed in the course of our study ( N OBS = 271; Table ) are slightly higher than these past census estimates.…”