AUTHORS: Daniel Isermann, USGS-Wisconsin Cooperative Fishery Research Unit; Ryan Bohen, Wisconsin Cooperative Fishery Research Unit; Daniel Dembkowski, Wisconsin Cooperative Fishery Research Unit; Alexander Latzka, Wisconsin Department of Natural Resources; Joseph Hennessy, Wisconsin Department of Natural Resources
ABSTRACT: Bigmouth buffalo Ictiobus cyprinellus and smallmouth buffalo Ictiobus bubalus (herein buffalo) are native, non-game fishes that rarely receive management attention. Increased participation in bowfishing has prompted efforts to better understand the population dynamics of buffalo and other native fish to determine their resiliency to harvest. Buffalo are native to many water bodies in Wisconsin, but little information exists regarding their population dynamics and contribution to bowfishing harvest. Consequently, our research objectives were to: 1) describe age composition, reproductive traits, and population dynamics for buffalo populations in Wisconsin; 2) assess their resiliency to harvest, and 3) determine the contribution of buffalo to harvest at bowfishing tournaments. We collected buffalo from 14 Wisconsin waterbodies with the help of the Wisconsin Department of Natural Resources and Wisconsin Bowfishing Association (WBA). Fish were selected for age estimation using a modified age-length key approach. Lapillus and asteriscus otoliths were used for age estimation. Age structure of buffalo populations varied considerably among populations, with maximum ages ranging between 15 and 70 years. Maturation schedules also varied, with age at 50% maturity ranging between 2.0 and 6.5 years and length at 50% maturity ranging between 382 and 505 mm. Three populations were oversampled (100≤ fish) to determine the minimum number of fish in a subsample needed to fully represent age composition in the population. Bowfishing harvest was recorded at each WBA tournament in 2023 and will be recorded again in 2024. All fish brought to the weigh-in were enumerated and identified to species or species group. Contribution of buffalo to tournament harvest peaked at 70.9% at the first tournament and was lower at the next four tournaments at 10.7%, 6.0%, 0.3% and 3.5%, respectively. Our research provides fishery managers with landscape-level population information on buffalo in Wisconsin and that may help inform future management decisions.
