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The management of fish populations often requires an understanding of how density‐dependent effects influence population dynamics. In systems where natural populations are supplemented with stocking, the question of “how much food is available” becomes increasingly important. One typical approach for assessing density‐dependent interactions is to identify disparities between fish consumption rates and food availability. The objective of our study was to determine whether seasonal lake prey production could support Brook Trout Salvelinus fontinalis consumption demand in Owhi Lake, Washington, at observed abundances. Brook Trout were collected seasonally from 2015 to 2017 to obtain information on length, weight, age, diet, growth, and mortality. Population abundance was estimated in summer by using hydroacoustic surveys. Littoral invertebrates and pelagic zooplankton were collected concurrently with fish to enumerate biomass and production. Bioenergetics modeling was used to estimate prey consumption by Brook Trout. In conjunction with supply–demand comparisons, we used growth efficiencies and maximum consumption rates to further identify potential seasonal and annual food limitations. Our results suggest that prey production could support Brook Trout consumption demand for all years, but littoral invertebrate consumption was close to or exceeded prey production in summer and fall 2017. Growth efficiency was lowest and maximum consumption rates were highest in summer 2017 relative to all other seasons and years. In addition to observed diet switching from littoral invertebrates to zooplankton in summer 2016 and 2017, we concluded that lower growth efficiencies, lower annual survival rates, and increased consumption rates were influenced by littoral invertebrate production. The Owhi Lake Brook Trout stocking program may require adaptive management (i.e., annual evaluations) to balance natural recruitment.

Objective: Production of Chinook Salmon Oncorhynchus tshawytscha in hatcheries can unintentionally produce large numbers of age-1 males, termed "minijacks," which pose ecological and genetic risks to target and nontarget populations. We evaluated the postrelease distribution of minijacks produced in a hatchery captive broodstock program targeting the White River in the Columbia River basin between 2010 and 2015.Methods: Fish were passive integrated transponder (PIT)-tagged in the hatchery (n = 218,555), and databases were searched to determine movement behavior and final detections on fixed PIT tag antenna arrays during the year in which they were released.Result: Two main movement behaviors were detected: (1) residuals, which moved solely within the subbasin of release; and (2) migrants, which moved downstream into the Columbia River and then reascended the Columbia River in the year of release. Minijacks that reascended fish ladders in the Columbia River were most often detected at Rock Island and Bonneville dams, the nearest and furthest detection locations downstream of the Wenatchee River. Minijacks were last detected in all locations where spring Chinook Salmon spawn in the Wenatchee River subbasin (seven tributaries and one main-stem area) and also in the Entiat River (an adjacent watershed); minijacks in eight of the nine locations were considered strays.Estimates of minijacks that strayed outside of the White River were between 61% and 100% annually and were influenced by release location. Minijacks were also more abundant than males of all older ages in some of the tributaries during some years.In addition, they were detected in these tributaries during periods when anadromous adults migrate into spawning areas and when spring Chinook Salmon spawn. Conclusion:The large amount of minijack production and the spatial and temporal overlap could pose genetic and ecological risks to both target and nontarget populations and particularly high straying poses risks to the maintenance of betweenpopulation genetic variability.

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Routine lethal sampling on small, conservation, or threatened populations may be unsustainable. Therefore, determining if alternative, nonlethal structures can provide accurate age data is important. We evaluated nonlethal structures (scales and pectoral fin rays) in conjunction with otoliths collected from lentic Brook Trout Salvelinus fontinalis in Washington State. We used age‐bias plots, percent agreement, and coefficient of variation to determine how scale or fin ray age estimates compared with otolith estimates, which had been validated in a previous study. Prior experience with aging specific structure types was the primary variable affecting age agreement with validated otolith‐determined age among three age readers. In general, fin rays and scales did not consistently reflect otolith age. Between‐structure coefficient of variation was 17.8–19.1% for scales and fin rays, and between‐structure percent agreement (within 1 year) was 80–82%. Individual percent agreement within 1 year was highest (92% and 86% for fin rays and scales, respectively) and coefficient of variation was lowest (9.0% and 14.8%, respectively) for the most experienced reader. Agreement of age estimates between readers improved with experience aging specific structures. Our study suggests that otolith data remains the preferred option.