A Comparison of Modified Fyke Nets for Evaluating Fish Assemblage and Population Structure

Modified fyke nets have long been used by fisheries managers to assess species composition and evaluate population characteristics of individual species.  Despite their widespread use, only recently have recommendations for standard fyke net specifications been made.  Therefore, we evaluated species composition and catch rates, size structure, and sample size requirements for bluegill (Lepomis macrochirus), black crappie (Poxomis nigromaculatus), and white crappie (P. annularis) in seven Iowa lakes in the fall of 2009 using two different fyke nets.  Fyke net specifications followed a recently recommended standard design and that currently used by Iowa Department of Natural Resources (IDNR).  Overall, the standard fyke net sampled more individuals and species than the IDNR net.  Additionally, mean catch rates of the focal species were consistently higher with the standard fyke net.  Size structure comparisons were limited by fewer than 125 stock-length fishes sampled in several lakes, but when comparison was possible, size structure was similar between the fyke net types.  The number of samples needed to obtain at least 125 stock-length individuals with standard fyke nets was consistently lower than that for IDNR fyke nets for all species.