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T‐bar anchor tags can be used to obtain recapture data from anglers, directly estimate exploitation, and evaluate population dynamics. However, their use by biologists to study anadromous salmonid fisheries is limited. Two hurdles to adoption include the functional difficulty of tagging large anadromous salmonids using conventional tagging equipment and a lack of information on tag loss by large anadromous salmonids and how it changes over time. As such, our objectives were to (1) describe a T‐bar anchor tagging system modified to study adult steelhead Oncorhynchus mykiss(anadromous Rainbow Trout) and (2) present an instantaneous tag loss model for steelhead that allows estimation of tag loss over time. First, we developed a modified tagging system by tagging hatchery‐obtained steelhead carcasses and live, resident Rainbow Trout larger than 500 mm using a variety of hardware and tag dimensions. Next, we double‐tagged adult steelhead captured at the Lower Granite Dam adult fish trap, Washington, United States. We then used data from 182 recaptured steelhead to fit an instantaneous tag loss model. Last, we investigated whether steelhead tag loss was related to body length. Tag loss was generally low within the time period under study (i.e., up to 221 days between release and recapture). The estimated probability of tag loss was 0.034 at release, 0.044 at 1 month, and 0.113 at 8 months. We failed to detect significant differences in tag loss parameters between two data subsets consisting of small (<720‐mm) and large (≥720‐mm) steelhead. T‐bar anchor tags are useful external tags for studying adult steelhead during their upstream migration. Because anglers can be used to provide recapture data, T‐bar anchor tags may be particularly useful where angler effort is high or direct estimation of fishery exploitation is desired. Impact StatementWe developed a modified T‐bar anchor tag to study anadromous salmonids, double‐tagged adult steelhead during their upstream migration, and modeled the probability of tag loss through time. The rate of tag loss was low, indicating that modified T‐bar anchor tags are suitable for studying steelhead during their upstream migration. We developed a modified T‐bar anchor tag to study anadromous salmonids, double‐tagged adult steelhead during their upstream migration, and modeled the probability of tag loss through time. The rate of tag loss was low, indicating that modified T‐bar anchor tags are suitable for studying steelhead during their upstream migration.

The potential influence (i.e., impact rate) of catch‐and‐release fisheries on wild steelhead Oncorhynchus mykissis poorly understood and is a function of the abundance of wild fish, how many fish are encountered by anglers (i.e., encounter rate), and the mortality of fish that are caught and released. In Idaho, estimates of wild steelhead encounter rates have been derived using the number of wild and hatchery steelhead passing Lower Granite Dam, the number of hatchery steelhead harvested, and the number of hatchery steelhead caught and released. The method includes assumptions that hatchery and wild steelhead have equal encounter rates and catch‐and‐release mortality is 5% for wild steelhead. Here, we investigated wild and hatchery steelhead encounter rates by anglers, estimated catch‐and‐release mortality, and concatenated both aspects to examine how existing recreational steelhead fisheries influence wild steelhead mortality. We sampled, tagged, and released 1,251 spawn‐year 2020 (SY2020) and 1,956 spawn‐year 2021 (SY2021) adult steelhead at Lower Granite Dam with T‐bar anchor tags and passive integrated transponder (PIT) tags to estimate steelhead encounter rates and catch‐and‐release mortality. Differences in survival of caught steelhead and those not reported as caught were evaluated using detections at various locations (e.g., PIT arrays, weirs). Estimated encounter rates were 43.7% (95% credible interval; 28.2%, 100.0%) for wild fish and 46.7% (29.6%, 100.0%) for adipose‐clipped fish in SY2020. In SY2021, encounter rates were 47.2% (32.4%, 100.0%) for wild fish and 52.3% (37.1%, 100.0%) for adipose‐clipped fish. Based on detections of caught fish and those not reported as caught, catch‐and‐release mortality of wild steelhead was estimated to be 1.6% (0.0%, 5.2%). Wild steelhead impact rates were 0.7% (0.0%, 2.7%) in SY2020 and 0.7% (0.0%, 2.8%) in SY2021. Estimated rates of impact on wild steelhead were consistent and low across years despite major differences in the structure of the fisheries. Our results suggest assuming that encounter rates are equal between hatchery and wild steelhead, and that steelhead catch‐and‐release mortality is 5%, will likely lead to a conservative estimate of the wild steelhead impact occurring from catch‐and‐release fisheries. Impact statementWith wild steelhead numbers declining in many parts of North America, a dilemma between providing angling opportunity and wild steelhead conservation can develop. We show that encounter rate plays a larger role than mortality regarding catch‐and‐release angling on overall impact rates. Our method provides a direct, reliable estimate of encounter rates across multiple scales. With wild steelhead numbers declining in many parts of North America, a dilemma between providing angling opportunity and wild steelhead conservation can develop. We show that encounter rate plays a larger role than mortality regarding catch‐and‐release angling on overall impact rates. Our method provides a direct, reliable estimate of encounter rates across multiple scales.