Kendall Ashley
Spatial Gradients in the Life History Characteristics of Ohio River Sauger
Abstract
Sauger (Sander canadensis) is one of the most recreationally harvested sport fish in the Ohio River. Consequently, these populations face high exploitation, which can lead to truncated size and age distributions, growth overfishing, and poor-quality fisheries. Previous work has found intraspecific variation in certain life history traits for Sauger, with both growth rate and mortality increasing downstream. However, little is known about how other life-history characteristics, such as fecundity and length at maturity, vary along this gradient. Understanding the variation in these reproductive traits can aid fisheries management in maintaining Sauger populations, as they directly influence the survival of offspring and, ultimately, recruitment. To address this knowledge gap, our study aimed to: 1) characterize fecundity for Sauger on the Ohio River, 2) determine if and how length at maturity varies from upstream to downstream, and 3) explore growth rate differences between male and female Saguer from upstream to downstream. We collected 246 Sauger using nighttime electrofishing, analyzed fecundity and egg diameter of 25 mature females, characterized length at maturity using logistic regression curves, and evaluated growth patterns using the von Bertalanffy growth function. Results showed fecundity and egg diameter increased with fish length and weight, although comparisons between sites could not be made due to the small number of mature females in our sample. Significant spatial differences in length at maturity were observed, with higher probabilities of maturity at smaller sizes in upper river sites, and the von Bertalanffy growth function revealed that males grew faster but reached smaller maximum lengths than females. These findings highlight the need for site-specific management practices and further research on reproductive traits across different river sections to sustain Sauger populations.
Significance Statement
Understanding the variation in reproductive traits of Sauger (Sander canadensis) along the Ohio River is crucial for sustainable fisheries management. As a popular sport fish facing high levels of exploitation, the Sauger population is at risk of overfishing, which can reduce population size, alter age and size structures, and degrade the overall quality of the fishery. This study provides key insights into how fecundity, length at maturity, and growth rates differ spatially and between sexes, offering a foundation for more targeted site-specific management practices. By addressing these knowledge gaps, our findings help to inform conservation strategies that can maintain healthy populations and ensure the long-term viability of Sauger fisheries, benefiting both ecosystems and the recreational fishing community.
Hwan Chen
Growth and recruitment of Ohio River Catfishes based on otolith analysis
Abstract
Catfishes provide important recreational and commercial fisheries in Ohio, so maintaining sustainable fisheries is essential for managers. Population dynamics of riverine catfishes should be further studied with reservoir populations. To quantify population characteristics of catfishes in the Ohio River, the Ohio Department of Natural Resources-Division of Wildlife (ODNR-DOW) sampled Blue Catfish Ictalurus furcatus and Flathead Catfish Pylodictus olivaris using standardized low-frequency electrofishing and Channel Catfish Ictalurus punctatus using tandem baited hoop nets in two pools (Markland and R.C Byrd) of the Ohio River in 2023. The ODNR-DOW collected a length-stratified sample of all catfishes for age analysis using otoliths. We used images of sectioned otoliths to back-calculate length at an age to compare first-year growth (FYG) and recruitment between the Markland and R.C. Byrd pools. We also assessed relationships between FYG and recruitment using flow gauge data provided by ORSANCO in the Ohio River and pool-specific major tributaries because catfish spawn in both tributary and mainstem rivers.
Significance Statement
Catfishes are important sport species for recreational and commercial fishers and play important roles in riverine food webs. Despite this importance, knowledge gaps remain for riverine catfish populations, such as drivers of variation in growth and recruitment. Understanding factors contributing to spatial and temporal variation in growth and recruitment can empower us to take responsible management actions aimed at maintaining sustainable fisheries.
