Red swamp crayfish (Procambarus clarkii) is an invasive species that has recently become established in the Chicago Area Waterway System (CAWS). This species has large ecological impacts and poses a threat of invading the Great Lakes because it is established in the North Shore Channel (NSC) which flows out of Lake Michigan. We have been intensively trapping P. clarkii in the NSC for the last eight years with the goal of reducing population growth and spread of the species. Trapping is focused on the area where P. clarkii is at highest density. From early June until late October we maintain roughly 200 traps in this area. Traps are cleared and re-baited twice a week during June – August and once per week thereafter. This has produced a large dataset that gives Catch Per Unit Effort (CPUE; average number of P. Clarkii per trap) over several hundred trapping days. CPUE fluctuates both within and among seasons, ranging from near zero to as high as 4.06. Differences can be high even on consecutive trapping days. If we can determine factors that affect CPUE it will be possible to predict days when our efforts could remove more of this invader. The goal of this project is to determine the relationship between CPUE and air temperature (°C), water temperature (°C), lunar illumination (% illuminated), and total precipitation (mm). Results from the 2025 field season show that each of these environmental factors is positively related to CPUE; lunar illumination (linear regression, R2 = 0.044), water temperature (R2 = 0.110), daily mean air temperature (R2 = 0.128) and daily minimum air temperature (R2 = 0.150). Ongoing work is relating these factors to our full eight years of data so that we can better understand the relationship of these environmental factors to CPUE. Results will be used predictively so that we can concentrate our future efforts at times that crayfish are most susceptible to being trapped. This will allow us to further reduce the population density of P. clarkii in the NSC and to reduce the chance of the species reaching Lake Michigan.