Marc A Johnson

NOAA Fisheries · Sustainable Fisheries Division; West Coast Region

Anadromous Oncorhynchus mykiss (steelhead) express diverse migratory behaviors and life-history strategies. Adult migration timing diversity within steelhead is often categorized into divergent early- and late-migration phenotypes. On the Rogue River in Oregon, adult steelhead return from the ocean during distinct early-summer, late-summer, and win...

Fish that exhibit high foraging activity or bold behavior can be particularly vulnerable to angling. If these traits are heritable, selection through harvest can drive phenotypic change, eventually rendering a target population less vulnerable to angling and consequently impacting the quality of the fishery. In this study, we used parental-based ta...

Many adult hatchery‐origin Pacific salmon return to their natal river but do not enter the hatchery, instead spawning in the river, where they can have detrimental genetic and ecological effects on naturally reproducing wild populations. This phenomenon is especially well documented in Elk River, Oregon Chinook Salmon, based on previous analyses of...

First recognized as threatened with extinction in 1999, native winter steelhead Oncorhynchus mykiss from Oregon’s Upper Willamette River (UWR) declined to a record-low 543 adult fish in 2017. This anadromous species has been seriously affected by habitat loss caused by impassable dams, intense predation from pinnipeds, and water pollution. Genetic...

We conducted a multi-year study in the Alsea River, Oregon, to determine whether the method of broodstock collection affects the vulnerability to angling of hatchery winter steelhead. In 2015 and 2016, unmarked, putatively wild steelhead were collected both by anglers and with hatchery traps, tissue sampled, then spawned to produce two experimental...

Induced triploidy typically causes sterility in teleost fishes, and has therefore been proposed as a tool to manage genetic risks that farmed and hatchery-produced salmon pose to wild populations. Application of this technology for aquaculture has been challenged by inferior growth, survivorship and, in the case of free-ranging anadromous salmonids...

Salmon straying is often defined as the failure of adults to return to their natal river system. However, straying within a river basin can be problematic if hatchery salmon do not return to their hatchery of origin and subsequently spawn in the wild with natural-origin salmon. We examined within-river straying patterns from 34 years of coded-wire...

An overview of research conducted through the Oregon Hatchery Research Center, highlighting coordination with ODFW hatcheries and the applications of results.

In this study we used microsatellite markers to genetically characterize 1,012 unmarked (presumed to be naturally produced), juvenile Oncorhynchus mykiss, collected at Willamette Falls in 2009, 2010 and 2011, and from multiple locations throughout the upper Willamette River basin in 2014. From the genetic data, we estimated the proportion of each y...

Many populations of Pacific salmon (Oncorhynchus spp.), including steelhead trout (O. mykiss), have experienced major declines as the result of habitat loss, excessive harvest and other anthropogenic activities. Hatchery operations have been implemented in many locations, including the Willamette River, Oregon, to mitigate the impacts of habitat lo...

Dams contribute to declines in fish abundance, in part, by blocking access to historical habitat. When fish ladders are infeasible, fish can be trapped below a dam and transported above to provide access to habitat. However, this conservation strategy has received little attention in the literature, and many questions regarding efficacy remain unan...

Dams, utilized for hydroelectric or flood control purposes, obstruct organism dispersal and have contributed to the decline of many migratory fish populations. For threatened Chinook salmon (Oncorhynchus tshawytscha) from the Willamette River Basin in Oregon, human-assisted reintroductions are being used to facilitate dispersal to historical habita...

Dams have contributed to the decline of migratory fishes by blocking access to historical habitat. The active transport (trap and haul) of migratory fish species above existing dams can sometimes support population recovery when the use of fish ladders or dam removal is infeasible. However, little is known about the efficacy of trap and haul conser...

Ploidy manipulation can be used to sterilize and thereby genetically contain cultured fish that might otherwise interbreed with wild stocks. For salmonids, pressure-induced triploidy is sometimes used to sterilize resident trout species. Few studies have evaluated effects of triploidy on performance of free-ranging anadromous salmon and steelhead,...

Dams have contributed to the decline of migratory fishes by blocking access to historical habitat. The active transport (trap and haul) of migratory fish species above existing dams can sometimes support population recovery when the use of fish ladders or dam removal is infeasible. However, little is known about the efficacy of trap and haul conser...

Conservation genetics studies are frequently conducted on Pacific salmon Oncorhynchus spp. to delineate their population structure and to quantify their genetic diversity, especially for populations that have experienced declines in abundance and are subject to anthropogenic activities. One such group of salmonids is steelhead O. mykiss (anadromous...

Many fish species have been negatively affected by the construction of high head dams because they alter temperature and flow regimes, as well as, impede fish migration. In recent years, managers have begun to reintroduce salmonids above dams in an effort to mitigate these effects. This strategy has been adopted on the South Fork McKenzie River, Or...

Effective management of Pacific salmon requires an accurate understanding of both population genetic diversity and structure. Spring Chinook Salmon Oncorhynchus tshawytscha from the upper Willamette River (UWR), Oregon, are listed as threatened under the U.S. Endangered Species Act, and although this evolutionarily significant unit is recognized to...

We used data from 17 brood years of coded‐wire‐tagged hatchery spring Chinook Salmon Oncorhynchus tshawytscha from the upper Willamette River to test for changes in mean age at maturity, fork length, and sex ratio. We found only limited evidence for any trend in age at maturity or sex ratio. However, Chinook Salmon sampled from tangle nets, recreat...

Construction of large dams in the upper Willamette River Basin of Oregon in the 1950s and 1960s blocked passage to adult spring Chinook and resulted in the loss of almost half of the most highly productive spawning and rearing habitat in the basin. In the McKenzie River basin, construction of Cougar Dam on the South Fork McKenzie River in 1963 bloc...

Salmon are well known for their extraordinary homing migrations from oceanic feeding grounds back to their river of origin to spawn. These migrations are governed by olfactory discrimination of homestream odors that juvenile salmon learn (imprint to) prior to their seaward migrations. Our previous laboratory studies have suggested that one componen...

An understanding of the processes that drive demographic trends constitutes a fundamental concept for fisheries management and conservation. In the upper Willamette River, spring Chinook salmon (Oncorhynchus tshawytscha) are produced by four hatcheries that are managed to meet harvest, mitigation and conservation objectives. Annual numbers of adult...

Salmon utilize olfactory cues to guide natal stream homing during spawning migrations. Both inorganic and biogenic chemicals have been proposed as odorants that might be used by salmon during homing. In this study, we used genomic DNA sequence data from nine salmonid species to compare nucleotide identities for orthologous main olfactory receptor (...

This report has been developed in response to Amendment 0001 to the USACE Special Studies and Evaluations Task Order (NWPPM-09-FH-05), which called for “a comprehensive review of the Willamette Basin spring Chinook hatchery program.” To accomplish this task, we have provided a brief overview of upper Willamette River (UWR) spring Chinook salmon bio...

This report has been developed in response to Amendment 0001 to the USACE Special Studies and Evaluations Task Order (NWPPM-09-FH-05), which called for “a comprehensive review of the Willamette Basin spring Chinook hatchery program.” To accomplish this task, we have provided a brief overview of upper Willamette River (UWR) spring Chinook salmon bio...

Coho salmon (Oncorhynchus kisutch) utilize olfactory cues to recognize and home to natal streams during spawning migrations. Chemically distinct river systems may promote directional selection for appropriately tuned olfactory receptor repertoires among Coho populations. Here, we use F(ST) outlier methods to test for a signal of selection over olfa...

Genotypic data from eight microsatellite loci are used to infer population structure, effective population size, migration rates, and patterns of allelic richness among wild and hatchery populations of Oregon coastal coho salmon (Oncorhynchus kisutch). Corroborating the results of a previous study, we found relatively weak genetic structure among c...

Habitat association of the spiny rat, Proechimys roberti (Rodentia: Echimyidae), was studied in the National Park of Brasília from October 1998 to June 1999. Thirty-three captures and 25 individuals were recorded with an effort of 1907 trap-nights. Stepwise logistic regression revealed a significant positive association between the presence of baba...

The Cerrado biome contains a rich mammal community, with an influence from the Amazonian and Atlantic rainforests, principally observed in the gallery forests. In this paper, through literature review, it is shown that the non-volant mammal community of the gallery forests is distinct from the mammal communities of any other physionomy of the Cerra...