AUTHORS: Sarah E. Hayden, South Dakota State University Department of Natural Resource Management; Justin M. Sturtz, South Dakota State University Department of Natural Resource Management, Christopher A. Cheek, South Dakota State University Department of Natural Resource Management
ABSTRACT: Understanding the age structure of fish populations within an ecosystem is crucial for fisheries managers, as it provides key insights into reproductive success, mortality rates, and overall population dynamics of the target species. Length-at-age relationships are a common metric used by fisheries managers to assess population health and growth patterns and identify whether growth is being stunted. In addition, age-length relationships are used by fisheries managers to determine the potential health of the fish populations and determine availability, reproductive success, and mortality. Currently, there is no data on the length-by-age of Channel Catfish (Ictalurus punctatus) on the North Platte River. The objective of this study is to establish age-length relationship for channel catfish in the North Platte River to inform management actions and parameterize bioenergetic models of catfish consumption. To accomplish this objective, channel catfish were sampled via boat electrofishing at two sites on the North Platte River in eastern Wyoming and pectoral spines were collected for age analysis. The spines were placed in 5.0mm microcentrifuge tubes filled with resin. After 24 hours of hardening, spines were removed from microcentrifuge tubes, and cut with a handsaw into 0.5mm-0.7mm thick slices. Slices were then looked at under a microscope, photographed, and aged two times to get an average age. A Von Bertalanffy growth model was applied to the length-at-age data to determine differences based on sampling location. The catfish that were aged ranged in age from 2 years to 8 years old and ranged in size from 12.9 inches to 28.3 inches in length. This data can be used by fisheries managers to determine the health of the catfish populations on the river and to aid in further research on this ecosystem.
