In the Pacific Northwest, several species of rockfishes (Sebastes spp.) are under extreme conservation measures due to low population levels. Although currently at healthy population levels, one species of interest is the black rockfish (S. melanops), which has been shown to utilize estuarine habitat during its early life history stages....
The 1988 status of yellowtail flounder stocks off the U.S. coast
of the Northwest Atlantic is assessed using U.S. and distant water
fleet commercial fishery statistics and Northeast Fisheries Center
bottom trawl survey data. Assessments of Southern New England and
Georges Bank stocks are revised using virtual population analysis of...
Early ocean residence is assumed to be a critical period for juvenile Pacific salmon Oncorhynchus spp. However, the specific mechanisms influencing growth and survival in the ocean have not been identified for most populations. Therefore, three hypotheses regarding the relationship between early marine residence and subsequent survival of mid-upper Columbia...
Natural and gabion modified habitats containing coho salmon
(Oncorhynchus kisutch) were observed and measured seasonally in East
Fork Lobster Creek, a fifth order stream in western Oregon. Coho
salmon usually inhabited backwater and secondary channel pools in
winter. Large wood debris complexes and undercut banks were the
primary sources of...
The Pigeon Guillemot (Cepphus columba) is now the only species of marine bird in Prince William Sound (PWS), Alaska that is listed as "not recovering" on the Exxon Valdez Oil Spill (EVOS) Trustee Council's Injured Resources List and has shown no sign of population recovery. During the 20 years since...
Habitat loss causes a reduction in available resources for wildlife, alters the configuration of remaining habitat, and may isolate wildlife populations. White-breasted nuthatches (Sitta carolinensis) are experiencing long-term population declines in the Willamette Valley of Oregon, where they are historically associated with oak woodlands. As secondary cavity-nesters, white-breasted nuthatches may...
Streams across the world are highly fragmented due to the presence of in-stream barriers (e.g., dams and stream-road crossings), many of which restrict or block fish passage. Retrofitting or replacing these structures is a high priority for restoring habitat connectivity for native fishes and other aquatic organisms in the Pacific...
Infectious pancreatic necrosis (IPN) is an acute, contagious disease of trout fry
and fingerlings caused by viruses of the family birnaviridae. IPN disease usually results
in mortality that is inversely proportional to the age of the fish. While many studies
have been carried out to increase our understanding of IPN,...
Anthropogenic land use alterations such as livestock grazing and fire
suppression have greatly altered sagebrush grasslands of the Great Basin,
facilitating invasion of exotic annuals, increases in woody species, and losses of
native species. Much of the current research surrounding wildland and prescribed
fire in sagebrush dominated ecosystems has focused...
Shrub-steppe ecosystems of western North America provide habitat for many wildlife species, are important components of public and private rangelands, and offer recreational opportunities for millions of people. They are some of the most vulnerable ecosystems in the United States and have been altered by human activities such as livestock...
The quality and availability of forage fishes and invertebrates can affect the behavior and productivity of predators that rely on these resources. This study measures the proximate composition of forage fishes and invertebrates from the southeastern Bering Sea to estimate prey energy density (quality) using a method that is ecologically...
Genetic differences between early and late forms of
Alaskan chinook salmon (Oncorhynchus tshawytscha) were
identified using two genetic approaches: mitochondrial
DNA (mtDNA) analysis and protein electrophoresis. The
study populations consisted of early- and late-run chinook
salmon in each of the Kenai and Kasilof rivers in Alaska,
and a single population...
Models are commonly used to assess and predict wildlife response to management practices. Model validation is essential if managers are to use them with confidence. Fifteen forest bird-habitat relationship models were developed by biologists using data collected from private forestland in southwest Washington. These models predict species' probability of occurring...
The occurrence of band-tailed pigeons (Columba fasciata) three mineral sites in Western Oregon was studied during the summers of 1974-1976. Objectives of the study were o: determine seasonal patterns of utilization of mineral sites by pigeons of different sex and age classes; determine productivity of pigeon populations associated with Mineral...
Spatial capture-recapture (SCR) is employed for estimating abundance and density of species, particularly those that are cryptic or solitary, and evaluating how population density varies with habitat. However, it is uncertain whether estimates are biased when applied to species that aggregate, such as elk (Cervus canadensis). Wildlife managers in the...
One fundamental concern in conservation biology is species abundance. For many taxa, however, these data are costly to obtain via direct observation and thus limited in geographic or temporal scope. Very high-resolution satellite imagery provides a means to address these limitations and provide remotely-sensed counts of large, colonial species. We...
Species associations of fifteen major commercial groundfish species in the
northeastern Pacific ocean and their spatial and temporal characteristics were studied
using Oregon bottom trawl logbook data, 1987 to 1993. Screening procedures were used
to remove questionable data from the original logbook files, which resulted in the
exclusion of information...