The Effect of Weather on Smallmouth Bass (Micropterus dolomieu) Growth Rates in Jordan Creek, Illinois, Over a 20 Year Period

Jordan Creek, a tributary of the Vermilion River in Vermillion County, Illinois, has served as an area of research for many decades. Intensive research was conducted by R. Weldon Larimore in 1950 to better understand the large fish populations found in Jordan Creek. The Illinois stream was also essential in James Karr’s development of the Index of Biotic Integrity. To better understand more recent changes within Jordan Creek, we examined the growth rates of Smallmouth Bass (Micropterus dolomieu) using scales collected from 1997 to 2019. Scales were imaged using an ocular camera, and annuli distances were measured to estimate annual growth rates. Temperature and precipitation data from the National Climatic Data Center were used as predictor variables to explain differences in annual growth rates over this modern period. Our results will aid in determining which weather factors most influenced Smallmouth Bass growth. Moreover, the results can be used to determine if factors other than weather may have impacted Smallmouth Bass growth in Jordan Creek. This information can be used to better manage the fishery by predicting expected fish sizes based on anticipated weather changes.