Utility of Tandem Hoop Nets for Indexing Channel Catfish Structure and Growth
Mark K. Flammang, Randall D. Schultz, and Darcy N. Cashatt
Abstract.—Most channel catfish Ictalurus punctatus management in Iowa has revolved around annual maintenance stockings. Issues with supply and demand of advanced fingerling channel catfish necessitate a more proactive approach to Iowa channel catfish management. We performed mark–recapture population estimates on 17 channel catfish populations during summer from 2004 to 2008 using tandem set hoop nets baited with soybean cake. We used Pearson correlation analysis to test potential relationships between lake population density and biomass and numerous continuous variables, including channel catfish size distribution indices (proportional size distribution and proportional size distribution-preferred), catch per unit effort (CPUE), relative weight (Wr), and stocking rate. Channel catfish CPUE was significantly correlated with density. Channel catfish size distribution was negatively correlated with density, and negative density-dependent effects on growth (as indexed by the relative growth index [RGI]) were observed. Both density and CPUE were negatively correlated with RGI. Relative weight throughout the length range of channel catfish populations was positively correlated with RGI. A multiple regression model significantly explained channel catfish density, whereby Wr of channel catfish less than 508 mm total length and channel catfish stocking rate explained 60% and 17% of the variability, respectively. The ability to anticipate channel catfish density and how it relates to population characteristics such as stocking rate will be a valuable asset to fishery managers.