Population Trends of Flathead Catfish, Channel Catfish, and Blue Catfish in Impounded and Unimpounded Reaches of the Upper Mississippi River (1993-2007)

摘要

Using Long Term Resource Monitoring Program data collected from impounded (Pool 26) and unimpounded (Open River) reaches of the upper Mississippi River, we investigated population dynamics of flathead catfish Pylodictis olivaris, channel catfish Ictalurus punctatus, and blue catfish I. furcatus from random sites located in side channel border (SCB) and main channel border (MCB) habitats. Objectives were to (1) compare trends (1993-2007) of three catfishes collected in Pool 26 and Open River reaches of the upper Mississippi River, and (2) provide needed information to managers on population dynamics through time using a binary gear approach of active (i.e., daytime electrofishing) and passive gears (hoopnetting). Active gears resulted in a higher catch per unit effort (CPUE) of all catfishes in each habitat-reach combination as compared to passive gears. Passive gears resulted in negligible catches of blue catfish and flathead catfishes (e.g., mean of <1 fish/net night). Catch per unit effort usingactive gear resulted in a greater number of channel catfish captured in Pool 26 compared to the Open River, with Open River SCB habitat having the lowest CPUE in most years. Blue catfish in the Open River had a higher CPUE using active gear as compared to Pool 26, with the Open River MCB having the greatest CPUE. Flathead catfish had a higher CPUE in MCB habitat compared to SCB habitat, with the Open River MCB having the highest CPUE in most years. However, declining trends in flathead catfish appears to be occurring in Open River habitats while trends in flathead catfish appear to be slightly increasing in Pool 26. The most common length-classes captured were substock and stock-sized fish regardless of habitat, species, or reach. Trends for channel catfish were easily determined due to high catch rates; however, more monitoring and enhanced sampling is needed to accurately assess flathead catfish and blue catfish trends and to accurately determine demographics for all three species.