Explaining Channel Catfish Population Characteristics in Ohio Reservoirs

Abstract

North American fisheries management agencies commit considerable resources to managing reservoir fisheries for Channel Catfish Ictalurus punctatus, which often includes stocking. However, Channel Catfish population characteristics often vary greatly among reservoirs, resulting in variable and unpredictable fishery quality. We sampled Channel Catfish populations in 44 Ohio reservoirs with tandem, baited hoop nets to understand relationships among population characteristics (density, as CPUE from hoop nets; growth, as mean length at age 7; mortality, as total annual mortality from catch‐curve analysis; and size structure, as proportional size distribution), stocking, and the relationships between these characteristics and reservoir size (as surface area), predator density (as Largemouth Bass Micropterus salmoides electrofishing CPUE), and productivity (as chlorophyll‐a concentration). We used multiple linear regression and an information theoretic approach to select the most parsimonious models for explaining observed variation in Channel Catfish density, growth, mortality, and size structure. We found that population density varied greatly among our study reservoirs, and none of our models sufficiently explained variation in density. Reservoir size and the interaction between reservoir size and population density explained the most variation in Channel Catfish growth, but productivity was also important. Small reservoirs (≤101 ha) had low to moderate densities and growth was uniformly slow; however, in larger reservoirs, lower densities resulted in faster growth. Growth increased as productivity increased. Total annual mortality was uniformly low (<0.26) but increased with density. Faster growth led to populations with larger size structures. These outcomes show that the largest Ohio reservoirs (≥406 ha) are the most suitable for supporting populations with fast growth and large size structures. Dense populations (CPUE > 50 Channel Catfish/net set) resulted in slower growth, greater mortality, and poor size structure. Future research to understand natural recruitment in reservoir Channel Catfish populations could be important for explaining variation in density.

Indexing Reservoir Channel Catfish Population Density and Size Structure with Tandem, Baited Hoop Nets

“…2011), which weakens the ability to quantify relationships between Channel Catfish density and other variables (Michaletz 2009; Tyszko et al. 2021). Managers can account for such variation in assessment models if this variation is predictable (Wilberg et al.…”

“…Therefore, the large differences in CPUE observed in Missouri (0–469 fish/net set; Michaletz 2009) and Ohio (5–402 fish/net set; Tyszko et al. 2021) are likely more attributable to real differences in density than to differences in catchability. However, variable catchability introduces uncertainty in the density–CPUE relationship (Flammang et al.…”

“…(2013) and Tyszko et al. (2021). Specifically, each tandem net set consisted of three 3.4‐m‐long hoop nets (25‐mm bar mesh; Miller Net Company, Inc., Memphis, Tennessee) containing seven fiberglass hoops, with each hoop being about 0.8 m in diameter but gradually decreasing in diameter toward the cod end (Bodine et al.…”

“…We chose these reservoirs because they varied in size and stocking history; additionally, preliminary data (Tyszko et al. 2021, this special issue) suggested that the CPUE of Channel Catfish differed among them. Our study reservoirs were in the size range (10–600 ha) of reservoirs typically managed for Channel Catfish fisheries in the Midwest (Santucci et al.…”

Catfish 2020, A Clear Vision of the Future

“…Furthermore, they suggested that supplemental stockings may be having a deleterious effect on fisheries by slowing growth and resulting in high‐density populations comprised largely of small fish (Tyszko et al. 2021a, this special issue). The studies referenced above provide evidence that despite the large catfish management literature base, certain situations will require additional work to appropriately inform management.…”