Geology topics

Julie A. Henning

Publications and source records attributed to Julie A. Henning.

4 recordsLinked to original sources

USGS2013

Spatial consistency of chinook salmon redd distribution within and among years in the Cowlitz River, Washington

We investigated the spawning patterns of Chinook Salmon Oncorhynchus tshawytscha on the lower Cowlitz River, Washington, using a unique set of fine- and coarse-scale temporal and spatial data collected during biweekly aerial surveys conducted in 1991–2009 (500 m to 28 km resolution) and 2008–2009 (100–500 m resolution). Redd locations were mapped from a helicopter during 2008 and 2009 with a hand-held GPS synchronized with in-flight audio recordings. We examined spatial patterns of Chinook Salmon redd reoccupation among and within years in relation to segment-scale geomorphic features. Chinook Salmon spawned in the same sections each year with little variation among years. On a coarse scale, 5 years (1993, 1998, 2000, 2002, and 2009) were compared for reoccupation. Redd locations were highly correlated among years. Comparisons on a fine scale (500 m) between 2008 and 2009 also revealed a high degree of consistency among redd locations. On a finer temporal scale, we observed that Chinook Salmon spawned in the same sections during the first and last week. Redds were clustered in both 2008 and 2009. Regression analysis with a generalized linear model at the 500-m scale indicated that river kilometer and channel bifurcation were positively associated with redd density, whereas sinuosity was negatively associated with redd density. Collecting data on specific redd locations with a GPS during aerial surveys was logistically feasible and cost effective and greatly enhanced the spatial precision of Chinook Salmon spawning surveys.

North American Journal of Fisheries Management↗

USGS2011

Behavior and movement of formerly landlocked juvenile coho salmon after release into the free-flowing Cowlitz River, Washington

Formerly landlocked Coho Salmon (Oncorhynchus kisutch) juveniles (age 2) were monitored following release into the free-flowing Cowlitz River to determine if they remained in the river or resumed seaward migration. Juvenile Coho Salmon were tagged with a radio transmitter (30 fish) or Floy tag (1050 fish) and their behavior was monitored in the lower Cowlitz River. We found that 97% of the radio-tagged fish remained in the Cowlitz River beyond the juvenile outmigration period, and the number of fish dispersing downstream decreased with increasing distance from the release site. None of the tagged fish returned as spawning adults in the 2 y following release. We suspect that fish in our study failed to migrate because they exceeded a threshold in size, age, or physiological status. Tagged fish in our study primarily remained in the Cowlitz River, thus it is possible that these fish presented challenges to juvenile salmon migrating through the system either directly by predation or indirectly by competition for food or habitat. Given these findings, returning formerly landlocked Coho Salmon juveniles to the free-flowing river apparently provided no benefit to the anadromous population. These findings have management implications in locations where landlocked salmon have the potential to interact with anadromous species of concern.

Washington↗

USGS2007

Use of seasonal freshwater wetlands by fishes in a temperate river floodplain

This study examined the use of freshwater wetland restoration and enhancement projects (i.e. non-estuarine wetlands subject to seasonal drying) by fish populations. To quantify fish use of freshwater emergent wetlands and assess the effect of wetland enhancement (i.e. addition of water control structures), two enhanced and two unenhanced emergent wetlands were compared, as well as two oxbow habitats within the Chehalis River floodplain. Eighteen fish species were captured using fyke nets and emigrant traps from January to the beginning of June, with the most abundant being three-spined stickleback Gasterosteus aculeatus and Olympic mudminnow Novumbra hubbsi . Coho salmon Oncorhynchus kisutch was the dominant salmonid at all sites. Enhanced wetlands, with their extended hydroperiods, had significantly higher abundances of yearling coho salmon than unenhanced wetlands. Both enhanced and unenhanced emergent wetlands yielded higher abundances of non-game native fishes than oxbow habitats. Oxbow habitats, however, were dominated by coho salmon. Fish survival in the wetland habitats was dependent on emigration to the river before dissolved oxygen concentrations decreased and wetlands became isolated and stranding occurred. This study suggests that wetland enhancement projects with an outlet to the river channel appear to provide fishes with important temporary habitats if they have the opportunity to leave the wetland as dissolved oxygen levels deteriorate.

Washington↗

USGS2006

Juvenile salmonid use of freshwater emergent wetlands in the floodplain and its implications for conservation management

A recent trend of enhancing freshwater emergent wetlands for waterfowl and other wildlife has raised concern about the effects of such measures on juvenile salmonids. We undertook this study to quantify the degree and extent of juvenile Pacific salmon Oncorhynchus spp. utilization of enhanced and unenhanced emergent wetlands within the floodplain of the lower Chehalis River, Washington, and to determine the fate of the salmon using them. Enhanced emergent wetlands contained water control structures that provided an outlet for fish emigration and a longer hydroperiod for rearing than unenhanced wetlands. Age‐0 and age‐1 coho salmon O. kisutch were the most common salmonid at all sites, enhanced wetlands having significantly higher age‐1 abundance than unenhanced wetlands that were a similar distance from the main‐stem river. Yearling coho salmon benefited from rearing in two enhanced wetland habitats, where their specific growth rate and minimum estimates of survival (1.43%/d by weight and 30%; 1.37%/d and 57%) were comparable to those in other side‐channel rearing studies. Dissolved oxygen concentrations decreased in emergent wetlands throughout the season and approached the limits lethal to juvenile salmon by May or June each year. Emigration patterns suggested that age‐0 and age‐1 coho salmon emigrated as habitat conditions declined. This observation was further supported by the results of an experimental release of coho salmon. Survival of fish utilizing emergent wetlands was dependent on movement to the river before water quality decreased or stranding occurred from wetland desiccation. Thus, our results suggest that enhancing freshwater wetlands via water control structures can benefit juvenile salmonids, at least in the short term, by providing conditions for greater growth, survival, and emigration.

Washington↗