Demographics of a Commercially Exploited Population of Flathead Catfish (Pylodictis olivaris) in the Wabash River

Flathead catfish, Pylodictis olivaris, are a popular game and commercial fish in the Midwestern United States. In the lower 322 km of the Wabash River, flathead catfish are commercially and recreationally harvested by Illinois and Indiana fishers. Current management regulations are different between the two states; Illinois and Indiana have minimum length limits of 381 and 254 mm, respectively. Indiana has proposed changing their minimum length limit to 381 mm and allowing only one fish\u3e 889 mm to be harvested per day. My study examined the current status of flathead catfish in the Wabash River to determine a standardized sampling protocol and to provide management recommendations for Illinois. I sampled flathead catfish using AC and pulsed-DC electrofishing during the summer of 2010-2012. I also set hoopnets and trotlines in 2011, but only used hoopnetting in 2012. During 2010-2012, I collected 952 flathead catfish with a mean length and weight of 343±5.6 mm and 914.5±55.6 g, respectively. Mean age of the flathead catfish was 3.5±.07 years (range 0-9 years). Annually, flathead catfish relative weight was above 90% for the majority of gears used. Pulsed-DC electrofishing had the greatest catch per unit effort (28.2±2.3 fish/hour); howeverhoopnetting caught larger fish (hoopnet proportional size distribution (PSD)=88, pulsed-DC electrofishing PSD=40). Propportional size distribution indices were within target range to be consider as quality fisahery. My results suggest that a multiple gear approach including pulsed-DC electrofishing and hoopnetting is critical to adequately assess flathead catfish populations in large rivers. My total annual mortality estimate (Z=0.51) was similar to previous estimates (49-56 percent) for flathead catfish in Midwestern large rivers (Donabauer 2009, Kwak et al 2006). My yield per recruit model implies that at current minimum length limits, the flathead catfish fishery is not sustainable. However, uncertainty in Illinois recreational angler preferences and stock-recruitment dynamics of flathead 7 catfish may be required to better inform potential management changes. My findings, regarding mortality, high population PSD, healthy size structure, and evidence of recruitment by the presence of age-0 fish (Figure 10), suggest that the Wabash River flathead catfish population is healthy and is a sustainable resource unless characteristics of the fishery change greatly. A drastic change to the status of the population may render current fishing practices unsustainable

Demographics of a commercially exploited population of flathead catfish (Pylodictis olivaris) in the Wabash River

Flathead catfish, Pylodictis olivaris, are a popular game and commercial fish in the Midwestern United States. In the lower 322 km of the Wabash River, flathead catfish are commercially and recreationally harvested by Illinois and Indiana fishers. Current management regulations are different between the two states; Illinois and Indiana have minimum length limits of 381 and 254 mm, respectively. Indiana has proposed changing their minimum length limit to 381 mm and allowing only one fish\u3e 889 mm to be harvested per day. My study examined the current status of flathead catfish in the Wabash River to determine a standardized sampling protocol and to provide management recommendations for Illinois. I sampled flathead catfish using AC and pulsed-DC electrofishing during the summer of 2010-2012. I also set hoopnets and trotlines in 2011, but only used hoopnetting in 2012. During 2010-2012, I collected 952 flathead catfish with a mean length and weight of 343±5.6 mm and 914.5±55.6 g, respectively. Mean age of the flathead catfish was 3.5±.07 years (range 0-9 years). Annually, flathead catfish relative weight was above 90% for the majority of gears used. Pulsed-DC electrofishing had the greatest catch per unit effort (28.2±2.3 fish/hour); howeverhoopnetting caught larger fish (hoopnet proportional size distribution (PSD)=88, pulsed-DC electrofishing PSD=40). Propportional size distribution indices were within target range to be consider as quality fisahery. My results suggest that a multiple gear approach including pulsed-DC electrofishing and hoopnetting is critical to adequately assess flathead catfish populations in large rivers. My total annual mortality estimate (Z=0.51) was similar to previous estimates (49-56 percent) for flathead catfish in Midwestern large rivers (Donabauer 2009, Kwak et al 2006). My yield per recruit model implies that at current minimum length limits, the flathead catfish fishery is not sustainable. However, uncertainty in Illinois recreational angler preferences and stock-recruitment dynamics of flathead 7 catfish may be required to better inform potential management changes. My findings, regarding mortality, high population PSD, healthy size structure, and evidence of recruitment by the presence of age-0 fish (Figure 10), suggest that the Wabash River flathead catfish population is healthy and is a sustainable resource unless characteristics of the fishery change greatly. A drastic change to the status of the population may render current fishing practices unsustainable

The Long-term Illinois, Mississippi, Ohio, And Wabash Rivers Fish Population Monitoring Program 2013

This report presents a summary of those data collected during segment 25(2013-14) of the Long-term Illinois, Mississippi, Ohio, and Wabash Rivers Fish Population Monitoring Program(LTEF), an annual survey executed by members of the Illinois Natural History Survey with funds administered by the U.S. Fish and Wildlife Service and the Illinois Department of Natural Resources. Sampling for the LTEF program was conducted throughout the state’s largest rivers: six reaches of the Illinois River Waterway, six segments or pools of the Mississippi River, four segmentsor pools of the Ohio River,five segments of the Wabash River, and navigable portions of the Iroquois and Kankakee Rives. In all segments of the LTEF program, all fish species collected were accurately identified, tallied, measured, and weighed. The catchrates of sportfishspecies were calculated as the number of individuals collected per hour (CPUEN± standard error).Structural indices [Proportional Size Distribution (PSD) and Relative Weight (Wr)] were also calculated for species of interest to regional managers. Catch rates and species richness varied greatly among all sampling locationsand sampling periods. Emerald shiners and gizzard shad comprised the majority of the individuals caught, while silver carp and common carp accounted for the greatest proportion of the biomass collected in most sampling areas of the survey. The analysis of CPUEN and PSD trends in sportfish populations sampled by the program may indicate inter-annual recruitment patterns in sportfish populations around the state. Both shovelnose sturgeon and blue catfish were the two species most commonly encountered in the gill net surveys.Illinois Department of Natural Resources, Division of Fisheriesunpublishednot peer reviewe