Assessments of threatened wild Snake River steelhead Oncorhynchus mykiss have historically been limited due to a lack of stock‐specific information and difficulties in field sampling efforts. We used genetic stock identification (GSI) to estimate the composition of wild adult steelhead migrating past Lower Granite Dam on the Snake River between August 24 and November 25, 2008. Further, we combined genetic data with information on sex, length, age, and run timing to examine for differences in life history or demography among stocks. In total, 1,087 samples collected at the dam were genotyped with 13 standardized steelhead microsatellite loci and a new modified Y‐chromosome‐specific assay that differentiates sex. A genetic baseline of 66 populations was used to complete GSI of unknown‐origin samples from Lower Granite Dam. Large differences in reporting group (stock) contributions were observed for the run as a whole; the Snake River–lower Clearwater River reporting group had the largest single contribution of 36.1% (95% confidence interval [CI] = 30.2–39.7%). Other large contributions were 15.4% (12.8–18.7%) from the upper Clearwater River reporting group and 13.9% (12.5–18.7%) from the lower Salmon River reporting group. Smaller contributions came from the other six reporting groups (Imnaha River: mean = 9.5%, 95% CI = 6.8–13.6%; upper Salmon River: 9.2%, 5.1–11.3%; South Fork Clearwater River: 7.6%, 4.3–8.9%; Middle Fork Salmon River: 5.1%, 3.5–6.4%; South Fork Salmon River: 2.7%, 1.3–3.6%; Elk Creek: 0.5%, 0.0–1.2%). Significant differences in reporting group contributions were observed when samples were grouped according to length, age, and run timing differences. Of the samples analyzed, 372 (34.9%) were identified as males and 694 (65.1%) were identified as females. Our results demonstrate that the GSI methodologies applied to Snake River steelhead have the potential of providing an efficient, minimally intrusive tool for obtaining stock‐specific abundance of this threatened distinct population segment. This technology can assist future viability status assessments of Snake River steelhead by contributing to refinements in population delineations, productivity calculations, and annual stock‐specific estimation of life history characteristics (e.g., age structure, sex ratio, and run timing).

We compared estimates of population abundance and size structure for Yellowstone cutthroat trout Oncorhynchus clarki bouvieri obtained by electrofishing 77 stream segments across southeastern Idaho in the 1980s and again in 1999–2000 to test whether populations of Yellowstone cutthroat trout had changed. Sites sampled in the 1980s were relocated in 1999–2000 by using maps and photographs or by finding original site‐boundary stakes, so that the same reach of stream was sampled during both periods. Abundance of Yellowstone cutthroat trout longer than 10 cm did not change, averaging 41 fish/100 m of stream during both the 1980s and 1999–2000. The proportion of the total catch of trout composed of Yellowstone cutthroat trout also did not change, averaging 82% in the 1980s and 78% in 1999–2000. At the 48 sites where size structure could be estimated for both periods, the proportion of Yellowstone cutthroat trout that were 10–20 cm long declined slightly (74% versus 66%), but the change was due entirely to the shift in size structure at the Teton River sites. The number of sites that contained rainbow trout O. mykiss or cutthroat trout × rainbow trout hybrids rose from 23 to 37, but the average proportion of the catch composed of rainbow trout and hybrids did not increase (7% in both the 1980s and 1999–2000). Although the distribution and abundance of Yellowstone cutthroat trout have been substantially reduced in Idaho over the last century, our results indicate that Yellowstone cutthroat trout abundance and size structure in Idaho have remained relatively stable at a large number of locations for the last 10–20 years. The expanding distribution of rainbow trout and hybrids in portions of the upper Snake River basin, however, calls for additional monitoring and active management actions.

Parentage-based tagging (PBT) is a non-lethal, genetic tagging method that has been successfully applied in hatchery supplemented populations to manage hatchery broodstock and monitor hatchery harvest and straying rates. We show that PBT can also improve the accuracy of escapement estimates by significantly reducing the number of hatchery-origin fish falsely classified as natural-origin. Unlike conventional abundance estimates, which use physical marks and tags to distinguish hatchery individuals from their wild counterparts, PBT identifies origin independent of physical form. We applied PBT to populations of Chinook Salmon (Oncorhynchus tshawytscha) and Steelhead (O. mykiss) which are classified as threatened under the Endangered Species Act and subject to extensive hatchery supplementation efforts. For spawn years 2014-2018, 16,511 adipose-intact Chinook Salmon and 21,953 adipose-intact Steelhead were sampled, and PBT identified 19.6% of returning Chinook Salmon and 8.3% of Steelhead were of hatchery-origin, despite having no physical or mechanical marks. The 90% confidence intervals for escapement estimates of natural-origin Chinook Salmon and Steelhead made with and without corrections using PBT were non-overlapping for nine of ten comparisons indicating that failing to account for unmarked, untagged hatchery-origin fish would result in a significant overestimation of natural abundance.

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II.

Abstract-In 2-stage fishery sampling, abundance is often estimated by using a primary sampling gear and total abundance is then partitioned into groups of interest by applying data on composition derived from a secondary sampling gear. However, the literature is sparse on statistical properties of estimates of run composition. We examined the accuracy and precision of estimators of composition of wild steelhead (Oncorhynchus mykiss) in the Snake River, in the Pacific Northwest. We simulated estimators, using pooled and time-stratified data. We compared confidence intervals (CIs) determined on the basis of asymptotical normality or a 2-stage bootstrap method. Stratified estimators were unbiased, except in a few cases. Joint CIs (all groups considered simultaneously) had coverages near nominal. Conversely, pooled estimators performed poorly; the proportion of biased estimates increased as the number of groups estimated increased. Using empirical data, we show that CIs met precision goals for most groups. Half-widths of CIs decreased and stabilized as the number sampled and group abundance increased. In complex scenarios, estimates of small groups will yield poor precision and some may be biased, but a stratified estimate with a conservative joint CI can be of practical use. The 2-step bootstrap approach is flexible and can incorporate other sources of variability or sampling constraints.

BackgroundThe genu valgum deformity seen in the Ellis-van Creveld syndrome is one of the most severe angular deformities seen in any orthopaedic condition. It is likely a combination of a primary genetic-based dysplasia of the lateral portion of the tibial plateau combined with severe soft-tissue contractures that tether the tibia into valgus deformations. Progressive weight-bearing induces changes, accumulating with growth, acting on the initially distorted and valgus-angulated proximal tibia, worsening the deformity with skeletal maturation. The purpose of this study is to present a relatively large case series of a very rare condition that describes a surgical technique to correct the severe valgus deformity in the Ellis-van Creveld syndrome by combining extensive soft-tissue release with bony realignment.MethodsA retrospective review examined 23 limbs in 13 patients with Ellis-van Creveld syndrome that were surgically corrected by two different surgeons from 1982 to 2011. Seven additional patients were identified, but excluded due to insufficient chart or radiographic data. A successful correction was defined as 10° or less of genu valgum at the time of surgical correction. Although not an outcomes study, maintenance of 20° or less of genu valgum was considered desirable. Average age at surgery was 14.7 years (range 7–25 years). Clinical follow-up is still ongoing, but averages 5.0 years (range 2 months to 18 years). Charts and radiographs were reviewed for complications, radiographic alignment, and surgical technique. The surgical procedure was customized to each patient’s deformity, consisting of the following steps: Complete proximal to distal surgical decompression of the peroneal nerveRadical release and mobilization of the severe quadriceps contracture and iliotibial band contractureDistal lateral hamstring lengthening/tenotomy and lateral collateral ligament releaseProximal and distal realignment of the subluxed/dislocated patella, medial and lateral retinacular release, vastus medialis advancement, patellar chondroplasty, medial patellofemoral ligament plication, and distal patellar realignment by Roux-Goldthwait technique or patellar tendon transfer with tibial tubercle relocationProximal tibial varus osteotomy with partial fibulectomy and anterior compartment releaseOccasionally, distal femoral osteotomyResultsIn all cases, the combination of radical soft-tissue release, patellar realignment and bony osteotomy resulted in 10° or less of genu valgum at the time of surgical correction. Complications of surgery included three patients (five limbs) with knee stiffness that was successfully manipulated, one peroneal nerve palsy, one wound slough and hematoma requiring a skin graft, and one pseudoarthrosis requiring removal of hardware and repeat fixation. At last follow-up, radiographic correction of no more than 20° of genu valgum was maintained in all but four patients (four limbs). Two patients (three limbs) had or currently require revision surgery due to recurrence of the deformity.ConclusionThe ope...

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