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Columbia River hatcheries release millions of juvenile Chinook Salmon Oncorhynchus tshawytschato support fisheries and mitigate for historical productivity declines from dam construction and upriver habitat losses. Recent federal biological opinions for Federal Columbia River Power System operations also have mandated restoration of estuarine rearing habitats to mitigate for mortality of naturally produced (NP) salmon at main‐stem dams. We compared genetic stock compositions, distributions, abundances, and length frequencies of hatchery‐marked and unmarked Chinook Salmon to evaluate the extent of hatchery influence on nearshore estuarine habitat use and the potential for interactions between hatchery‐origin (HO) and NP salmon. Cumulative Chinook Salmon releases from all hatcheries in 2010 and 2011 dictated estuarine stock composition, abundance, and life histories during the spring–summer migration peak. Naturally produced salmon from the lower Columbia River populations, including many fry migrants, were most abundant, but larger HO juveniles also frequented nearshore sites, where their total biomass often equaled or exceeded that of NP fish. Large releases of a single stock of origin (Spring Creek Group fall run) in April and May created sharp pulses in the estuary entry timing of fingerling‐sized salmon and dominated abundance and stock composition at some sites. Successive releases from scores of hatcheries during spring and early summer ensured a consistent presence of HO salmon near shore, regardless of the habitat‐specific residence times of individual fish. Overall, the historical replacement of diverse wild populations with fewer hatchery stocks of a narrow size range and migration timing has intensified nearshore habitat use during the spring–summer migration peak and reduced life history variation of Columbia River Chinook Salmon. Such changes could undermine the fish conservation goals of both hatchery mitigation and estuary restoration programs.

AbstractUse of the Columbia River estuary by juvenile Pacific salmon Oncorhynchusspp. is garnering more attention as managers look to improve salmon survival through estuary restoration. Studies have shown that juvenile salmon are abundant in shallow-water habitats within the Columbia River estuary, but information on how juveniles exploit specific estuarine habitats is lacking. We used a combination of physical marks and PIT tag technology to record residence time, movement, and growth of juvenile Chinook Salmon O. tshawytscha, particularly subyearlings, within an emergent marsh of the Columbia River estuary during 2005, 2006, and 2008. We documented marsh-scale residency and movement within the marsh complex and channel-scale residency and movement within two small secondary channels. Many juvenile Chinook Salmon remained in the marsh for 2–4 weeks and increased in FL by 10–20 mm, with an average growth rate of 0.53 mm/d. Chinook Salmon entered secondary channels most frequently in late afternoon and occasionally did so against the tide. Our results indicate that subyearling Chinook Salmon take advantage of shallow estuarine habitat in the Columbia River to a greater extent than previously documented.Received January 8, 2016; accepted March 21, 2016 Published online June 21, 2016

Use of the Columbia River estuary by juvenile Pacific salmon Oncorhynchusspp. is garnering more attention as managers look to improve salmon survival through estuary restoration. Studies have shown that juvenile salmon are abundant in shallow-water habitats within the Columbia River estuary, but information on how juveniles exploit specific estuarine habitats is lacking. We used a combination of physical marks and PIT tag technology to record residence time, movement, and growth of juvenile Chinook Salmon O. tshawytscha, particularly subyearlings, within an emergent marsh of the Columbia River estuary during 2005, 2006, and 2008. We documented marsh-scale residency and movement within the marsh complex and channel-scale residency and movement within two small secondary channels. Many juvenile Chinook Salmon remained in the marsh for 2–4 weeks and increased in FL by 10–20 mm, with an average growth rate of 0.53 mm/d. Chinook Salmon entered secondary channels most frequently in late afternoon and occasionally did so against the tide. Our results indicate that subyearling Chinook Salmon take advantage of shallow estuarine habitat in the Columbia River to a greater extent than previously documented. Received January 8, 2016; accepted March 21, 2016 Published online June 21, 2016

The Dynamic Weather Routes (DWR) tool continuously and automatically analyzes active flights in en route airspace and finds simple route corrections to achieve more time- and fuel-efficient routes around convective weather. A strong partnership between the National Aeronautics and Space Administration (NASA), American Airlines (AA), and the Federal Aviation Administration (FAA) has enabled testing of DWR in real-world air traffic operations. NASA and AA have been conducting a trial of DWR at AA's Integrated Operations Control Center in Fort Worth, Texas since July 2012. This paper describes test results based on AA's use of DWR for their flights in and around Fort Worth Center (ZFW). Results indicate an actual savings of 3,949 flying minutes for G24 AA revenue flights from January 2013 through December 2014. Of these, 101 flights each indicate a savings of 15 min or more. Potential savings for all flights in ZFW airspace, corrected for savings flights achieve today through normal pilot requests and controller clearances without DWR, is about 100,000 flying minutes for 15,000 flights in 2013. Results indicate that AA flights with DWR in use realize about 15% more savings than non-AA flights. A weather forecast analysis examines the extent to which DWR routes rated acceptable by AA users remain clear of downstream weather. A sector congestion analysis indicates congestion could be reduced by about 20% if all flights fly DWR routes rather than nominal weather-avoidance routes. [ABSTRACT FROM AUTHOR]

Extensive efforts are underway to restore and conserve nearshore shallow water habitats in the Columbia River estuary with the intent of increasing the estuary's capacity to provide food, refuge, and other crucial ecosystem functions for juvenile salmon. Juvenile Chinook Salmon Oncorhynchus tshawytscha, including those from the five Evolutionarily Significant Units listed as threatened or endangered under the U.S. Endangered Species Act, are particularly expected to benefit from the habitat improvements. However, information on the temporal and spatial estuarine distributions of juveniles from specific populations or stocks is lacking and impedes restoration planning for at-risk salmon. We conducted a series of surveys to sample juvenile Chinook Salmon occupying shallow-water habitats with sandy beaches in six hydrogeomorphic reaches across the tidal freshwater portion of the estuary and also at one long-term reference site near the estuary mouth. Sites were sampled bimonthly over 26 months during 2010–2012 to capture seasonal patterns of stock-specific habitat use. Genetic stock identification analyses were conducted on the samples using microsatellite DNA loci and genotypic data representing spawning populations from throughout the Columbia River basin. We identified three tidal freshwater areas that could be distinguished by genetic stock composition. Lower tidal freshwater reaches were dominated by fall-run juveniles from West Cascade tributaries (>70%), upper reaches had a large proportion of fish from the upper Columbia River summer–fall stock (>60%), and middle reaches were characterized by greater stock diversity with no single stock contributing more than 30% in each reach. Stock-specific juvenile habitat use differed by season, life history type, and between natural and hatchery-produced fish. Data from this study provide improved descriptions of the near-shore estuary habitat use of several Columbia River genetic stocks of Chinook Salmon that can assist managers in the design and selection of estuary restoration projects. Received November 11, 2013; accepted February 18, 2014

AbstractExtensive efforts are underway to restore and conserve nearshore shallow water habitats in the Columbia River estuary with the intent of increasing the estuary's capacity to provide food, refuge, and other crucial ecosystem functions for juvenile salmon. Juvenile Chinook Salmon Oncorhynchus tshawytscha, including those from the five Evolutionarily Significant Units listed as threatened or endangered under the U.S. Endangered Species Act, are particularly expected to benefit from the habitat improvements. However, information on the temporal and spatial estuarine distributions of juveniles from specific populations or stocks is lacking and impedes restoration planning for at-risk salmon. We conducted a series of surveys to sample juvenile Chinook Salmon occupying shallow-water habitats with sandy beaches in six hydrogeomorphic reaches across the tidal freshwater portion of the estuary and also at one long-term reference site near the estuary mouth. Sites were sampled bimonthly over 26 months during 2010–2012 to capture seasonal patterns of stock-specific habitat use. Genetic stock identification analyses were conducted on the samples using microsatellite DNA loci and genotypic data representing spawning populations from throughout the Columbia River basin. We identified three tidal freshwater areas that could be distinguished by genetic stock composition. Lower tidal freshwater reaches were dominated by fall-run juveniles from West Cascade tributaries (>70%), upper reaches had a large proportion of fish from the upper Columbia River summer–fall stock (>60%), and middle reaches were characterized by greater stock diversity with no single stock contributing more than 30% in each reach. Stock-specific juvenile habitat use differed by season, life history type, and between natural and hatchery-produced fish. Data from this study provide improved descriptions of the near-shore estuary habitat use of several Columbia River genetic stocks of Chinook Salmon that can assist managers in the design and selection of estuary restoration projects.Received November 11, 2013; accepted February 18, 2014