Tag loss is an important consideration in tagging studies. We used two approaches to describe prestocking coded wire tag (CWT) loss in Lake Trout Salvelinus namaycush tagged by an automated tagging system and released in the Laurentian Great Lakes. First, four strains of Lake Trout tagged by an automated system through the Great Lakes Mass Marking Program were observed for up to 254 d to describe how tag loss and adipose fin clip success relates to time posttagging. Second, we also evaluated final tag loss and fin clip success from 197 tag lots from 2011 to 2013 that were tagged with an automated system to explore the factors affecting tag loss and fin clip success, and to compare tag loss and fin clip success rates with those from 1,080 tag lots from 1985 to 2003 that were manually tagged. Coded wire tag losses from experimental lots of four strains of Lake Trout were low and ranged from 2.8% to 5.7%. Coded wire tag losses stabilized 150 d posttagging, when fish had a mean length of 131 mm, which is far longer than that reported for other salmonines (30 d). We developed a descriptive model to correct for time effects on tag loss; tag loss could be estimated with high confidence after 100 d posttagging. Coded wire tag losses varied by genetic strain, possibly due to differences in body size and shape. Fish that lost a CWT were significantly smaller than fish retaining a CWT. In our comparison of the automated system with manual tagging, CWT loss across 197 automated tag lots was highly variable (0.0–14.0%), but it was <5.5% in 86% of samples and less than the loss rates from manually tagged fish (<5.5% in 72% of samples). Our results provide important details for CWT studies on Lake Trout and other species. Received July 28, 2015; accepted February 7, 2016 Published online June 1, 2016

Chinook Salmon Oncorhynchus tshawytscha were introduced into Lakes Michigan and Huron in the 1960s to diversify recreational fisheries and reduce overabundant, nonnative Alewife Alosa pseudoharengus. Alewife remain the primary prey of Chinook Salmon but have experienced substantial declines in abundance due to reduced food resources and salmonine predation pressure. The movements of Chinook Salmon have been linked to the density and spatial distribution of Alewife, but spatial patterns in Chinook Salmon growth have not been well documented and the temporal relationship between growth and Alewife density has not been evaluated during the current period of low Alewife abundance. We evaluated spatial and temporal variation in growth of Chinook Salmon in Lake Michigan and the U.S. waters of Lake Huron and explored linkages with Alewife density. Von Bertalanffy growth parameters were generally similar for recaptured coded‐wire‐tagged Chinook Salmon from different stocking locations and different recovery locations. Only a few small differences among stocking and recovery regions were evident, with regions divided into two subtly different groups with shared growth parameters. The small regional differences may be attributable to unique habitat and/or stocking characteristics of specific regions. In Lake Michigan average Chinook Salmon length at age also varied across years and was tightly coupled with annual lakewide densities of age‐1 and older Alewife, suggesting that Chinook Salmon growth from 2012 to 2016 was constrained by Alewife density. Our findings are consistent with evidence of lakewide movements associated with foraging and support continued management of Chinook Salmon in Lake Michigan as a single population. Furthermore, similar growth in Chinook Salmon from Lakes Michigan and Huron corroborates evidence that Chinook Salmon move from U.S. waters of Lake Huron to Lake Michigan to feed and reinforces the recent decision to include most fish stocked in northwestern Lake Huron in the Lake Michigan population when managing for predator–prey balance.

Automated coded‐wire‐tagging methods were recently applied to Brook Trout Salvelinus fontinalis for the first time, but information on tag loss and method efficiency is needed. We observed tag loss in Brook Trout over 210 d posttagging to determine the degree of tag loss and when tag loss stabilized for the 2015 year‐class. We also evaluated tag loss from two subsequent year‐classes. Brook Trout tag loss stabilized (i.e., reached the curve's inflection point) at 1.5% after 15 d posttagging and achieved its asymptotic maximum of 1.6% after 28 d. Tag loss rates for subsequent year‐classes were 1.7% and 2.3%. We also described throughput (fish tagged per hour) to evaluate method efficiency. Throughput ranged from 8,449 to 9,395 fish/h for Brook Trout and was comparable to observations on other salmonines; combined with the low rate of tag loss, this demonstrates the efficacy of automated methods for the marking and tagging of this species. In addition, rapid stabilization of tag loss in Brook Trout (15 d) was similar to that observed in Pacific salmonines but distinct from that recorded for other Salvelinus spp. (≥150 d), and underscored the need to directly measure species‐specific tag loss and its stabilization period and to avoid using closely related species as proxies.