Evaluation of Management Strategies for an Incidental Catch‐and‐Release Steelhead Fishery

Abstract

Managing fisheries for species of conservation concern, such as steelhead Oncorhynchus mykiss fisheries in Idaho where wild steelhead are incidentally caught and released, requires a tradeoff between providing opportunity for anglers to fish for hatchery-origin steelhead and managing conservation risk for wild steelhead. Understanding population-level effects of catch-and-release fishing is critical for effectively balancing this tradeoff. We used an integrated population model to evaluate population-level effects of incidental catch-and-release mortality on steelhead in Idaho and assessed the effectiveness of alternative management strategies for meeting fishery and population objectives. When simulated catch-and-release mortality or encounter rates were low, fishery, abundance, and conservation risk objectives were easily met by implementing fisheries annually, regardless of adult abundance. However, when simulated catch-and-release mortality rates were high, management strategies that required the population to surpass minimum thresholds for pre-season abundance were more likely to meet goals for minimizing conservation risk but limited fishing opportunity substantially. Results of this study provide managers with a framework that can be used to manage fisheries to meet fishery goals in the form of hatchery steelhead harvest while maintaining sustainable populations and minimizing risk to wild steelhead. The results also suggest that when implemented properly, it is possible to meet fisheries and conservation objectives simultaneously.

Encounter rates and catch‐and‐release mortality of steelhead in the Snake River basin

“…Encounter and catch‐and‐release mortality rates similar to those we estimated should pose little risk to steelhead populations (McCormick et al. 2021).…”

“…Hence, encounter rate plays a larger role in the overall impact rates when compared to the rate of mortality from catch-and-release angling. Encounter and catch-and-release mortality rates similar to those we estimated should pose little risk to steelhead populations (McCormick et al 2021).…”

Informing Management of Henrys Lake, Idaho, using an IntegratedCatch‐at‐AgeModel

“…Consequently, integrated models can result in larger prediction uncertainty (e.g., McCormick et al. 2021a, 2021b) than more traditional methods that may ignore or fail to fully account for uncertainty—particularly process uncertainty (Maunder and Punt 2013). Underestimation of prediction uncertainty can result in misleading low quantification of risk of alternative management or harvest scenarios (Butterworth et al.…”

“…Integrated models are acknowledged as providing more accurate propagation of uncertainty in the future state of nature (Aeberhard et al 2018) compared to deterministic models (which contain no uncertainty) or two-stage simulation models, where parameters and stochasticity are supplied externally (e.g., Leslie matrix projection models) to the model (Maunder and Punt 2013). Consequently, integrated models can result in larger prediction uncertainty (e.g., McCormick et al 2021aMcCormick et al , 2021b than more traditional methods that may ignore or fail to fully account for uncertainty-particularly process uncertainty (Maunder and Punt 2013). Underestimation of prediction uncertainty can result in misleading low quantification of risk of alternative management or harvest scenarios (Butterworth et al 2010).…”

Applications of Age–Length Keys for Assigning Ages to Juvenile Steelhead

“…Another key benefit of using ALKs to assign accurate ages to unaged fish involves tracking of age-specific movement and survival at later life history stages through PIT tags. Often, juvenile survival in freshwater systems is a data gap for steelhead and limits the ability to use complex population models or to effectively assess restoration actions (Katz et al 2007;McHugh et al 2017;McCormick et al 2020). Assigning accurate ages to unaged, PITtagged fish can aid in filling those data gaps and can provide the ability to monitor age-based movement and survival of juvenile steelhead.…”