Using Capture Probability of Smallmouth Bass in Missouri's Ozark Rivers to Provide a Statewide Perspective of Smallmouth Bass Populations

In Missouri, long-term monitoring of riverine Smallmouth Bass (Micropterus dolomieu) populations, by the Missouri Department of Conservation (MDC), is largely conducted at the individual waterbody scale.  Recently MDC staff combined data collected from 1998-2013 to provide a long-term statewide perspective of Missouri’s Smallmouth Bass populations.  However, to appropriately combine this data into one data set it was important to first evaluate variation in capture probability among waterbodies.  This evaluation helped ensure that results of the study were not biased by physical stream conditions or variations in electrofishing methods.  Two considerations were required to account for variation in capture probability: 1) the smallest and largest rivers were excluded and 2) only sites with at least five replicates were included in the analysis.  After making these considerations statewide capture probability and population metrics were calculated.  A few important statistics include: 1) mean capture probability of Smallmouth Bass was 15%, 2) the mean, long-term statewide proportional size distribution of 12”, 15”, and 18” fish was 40%, 7%, and 1% respectively, and 3) mean catch/effort (fish/hour) was 32.  This broad perspective will be important in providing managers with a statewide view of Missouri’s Smallmouth Bass populations that will aide in future management discussions.