Use of the North American Standard Gill Net for Sampling the Invasive White Perch: Information from Three Kansas Reservoirs

Abstract

The invasive White Perch Morone americana occurs intermittently throughout Kansas and is ubiquitous in three Kansas reservoirs. However, a paucity of information on the effectiveness of sampling gears for providing accurate and precise estimates of size structure and relative abundance for White Perch precludes reasonable assessments of the effectiveness of control measures. The North American standard gill net has been used to sample White Perch in Kansas since 2010. Previous studies have provided selectivity curves for several species that are sampled with this gear to mitigate overall size bias, which is inherently present in gill‐net catches. However, White Perch populations have not been included in these initial studies. We fit selectivity models to catch data from three Kansas reservoirs to adjust the gill‐net catch data for contact selectivity. We used the most parsimonious selectivity curve to adjust the values for White Perch capture at length for 10 years of catch data. Most of the adjusted samples resulted in meaningful changes to the length distributions. To test for the effectiveness of the North American standard gill net for sampling White Perch populations, we measured the precision of the relative abundance estimates for White Perch and the frequency of obtaining 100 stock‐size fish with a standard sampling effort from 9 to 10 years of historical gill‐net samples. Our results suggest the North American standard gill net provides precise and robust estimates for the relative abundance of stock‐sized White Perch, but a correction factor that is derived from the selectivity curve might be needed to accurately estimate relative abundance for small individuals and to evaluate population size structure.