Influence of Environmental Variables on Catch of Walleye Broodfish for Propagation Efforts

Walleye Stizostedion vitreum support recreational fisheries throughout their range but increasingly require annual stockings to maintain populations. In many areas of their distribution, Walleye broodfish are collected annually and manually spawned onsite before fertilized eggs are transported to fish culture facilities for rearing. As such, efficiency of these programs is reliant on effective capture of broodfish. Generalized additive models were used to explain the influence of eight environmental factors on catch per effort (CPE) of ripe female Walleye and male Walleye during brood collection events from Hillsdale Reservoir, Kansas, using data from 2009 to 2021 (excluding 2020). The ripe female model explained 63% of the deviance in CPE and identified the day of year, water temperature, moon illumination, previous autumn CPE of preferred-length fish (CPEp), and previous autumn proportional size distribution of preferred-length fish (PSDp) as influential variables. The male model explained 64% of the deviance in CPE and identified the day of year, change in barometric pressure from the previous day, water temperature, and previous autumn proportional size distribution of quality-length fish PSDq as influential variables. These findings provide useful information regarding collection of Walleye broodfish and can be leveraged to increase efficiency of future operations range-wide.