A Comparison of Two Methods for Sampling Bluegill and Redear Sunfish in Small Impoundments

Abstract

Bluegill Lepomis macrochirus and Redear Sunfish L. microlophus are highly regarded recreational species throughout North America. Management of these species relies on sampling methods that accurately and efficiently describe population characteristics of the target population. Largemouth Bass Micropterus salmoides and crappies Pomoxis spp. are commonly sampled with spring electrofishing and fall fyke netting, respectively. If lepomids can be effectively sampled concurrently with Largemouth Bass or crappies with one of these sampling methods, it would improve sampling efficiency in small impoundments. Our objective was to compare two sampling methods (North American standard fyke netting and electrofishing) for sampling Bluegill and Redear Sunfish populations in small impoundments by comparing size structure, sampling precision (relative standard error), and sampling efficiency (effort needed to collect 125 stock‐length fish). Typically, spring electrofishing caught a wider size range of Bluegill and Redear Sunfish than fyke nets, but proportional size distribution was similar between gears. However, length frequencies differed between gears in all impoundments for Bluegill and in three of five impoundments for Redear Sunfish. Electrofishing typically caught a greater proportion of large lepomids than fyke nets in those cases, though the differences were subtle and management decisions would likely be similar using data from either gear. With the exception of Pawhuska Lake (which had low catch rates leading to poor precision for both species and both gears), catch rates were typically high enough to collect sufficient numbers (125 stock‐length fish) of Bluegill to adequately describe size structure with 5–20 net‐nights for fyke nets or 4–28 transects for electrofishing, but Redear Sunfish sampling would require considerably more sampling effort to produce sufficient amounts of fish in most cases (24–79 net‐nights for fyke nets or 12–57 transects for electrofishing). Spring electrofishing is the more precise (lower relative standard error) of the two sampling methods for collecting lepomids.

Use of the North American Standard Gill Net for Sampling the Invasive White Perch: Information from Three Kansas Reservoirs

“…2016; Porta et al. 2021). A resampling approach was used to estimate the number of samples that is required to achieve RSE25 and a minimum of 100 stock‐size fish in 80% of cases by using 1,000 Monte Carlo simulations, drawing samples from the 583 net sets that were available from the three reservoirs from the 2010–2019 sampling events (Dumont and Schlechte 2004).…”

“…The number of individuals was simply a count of all of the captured stock-length White Perch. We used a target RSE of 25% (RSE25) and a minimum of 100 stocklength individuals as thresholds to describe precise and robust samples, respectively (Anderson and Neumann 1996;Dumont and Schlechte 2004;Koch et al 2014;Flammang et al 2016;Porta et al 2021). A resampling approach was used to estimate the number of samples that is required to achieve RSE25 and a minimum of 100 stock-size fish in 80% of cases by using 1,000 Monte Carlo simulations, drawing samples from the 583 net sets TABLE 1.…”

Comparison of age estimates and population characteristics for green sunfish using two otolith methods

“…Whole otoliths require minimal preparation and are less time consuming to prepare, compared to sectioned otoliths (Hoxmeier et al, 2001; Isermann et al, 2003; Kowalewski et al, 2012). However, use of whole otoliths may result in inaccurate age estimates for older fish or for populations exhibiting slow growth (Buckmeier & Howells, 2003; Hoyer et al, 1985; Porta et al, 2019). In cases where a population is slow growing or stunted, or if annuli appear to be constricted on the otolith margin, cracked otoliths are recommended to determine the precise ages of fish (Hales & Belk, 1992; Porta et al, 2019).…”

“…Whole otoliths require minimal preparation and are less time consuming to prepare, compared to sectioned otoliths (Hoxmeier et al, 2001;Isermann et al, 2003;Kowalewski et al, 2012). However, use of whole otoliths may result in inaccurate age estimates for older fish or for populations exhibiting slow growth (Buckmeier & Howells, 2003;Hoyer et al, 1985;Porta et al, 2019).…”

“…In cases where a population is slow growing or stunted, or if annuli appear to be constricted on the otolith margin, cracked otoliths are recommended to determine the precise ages of fish (Hales & Belk, 1992;Porta et al, 2019). Koch et al (2019) determined that whole otoliths provided precise age estimates for bluegill (Lepomis macrochirus) in Kansas up to age 8.…”