Publications
USGS research activities relevant to Alaska have yielded more than 9400 historical publications. This page features some of the most recent newsworthy research findings.
Filter Total Items: 2891
Sand lance as cornerstone prey for predator populations
Sand lance (Ammodytes) constitute a major prey for at least some populations of over 100 species of consumer, including 40 species of birds, 12 species of marine mammals, 45 species of fishes, and some invertebrates. Variation in the availability of sand lance (and other forage fishes) can have major effects on the breeding success and survival of their predators. Commercial fishing and other pres
Authors
Mary F. Willson, Robert H. Armstrong, Martin D. Robards, John F. Piatt
Sand lance: A review of biology and predator relations and annotated bibliography
Six species of sand lance (Ammodytes) in temperate and boreal regions are currently recognized. Sand lance can occupy a wide range of environmental conditions, but all appear to be dormant predominantly in winter, and one species is in summer also. They lack a swim bladder and spend much of their time buried in specific substrates. Copepods are the primary food. Spawning usually occurs in fall or
Comparison of aerial survey procedures for estimating polar bear density: Results of pilot studies in northern Alaska
The U.S. Marine Mammal Protection Act (MMPA) and International Agreement on the Conservation of Polar Bears mandate that boundaries and sizes of polar bear (Ursus maritimus) populations be known so they can be managed at optimum sustainable levels. However, data to estimate polar bear numbers for the Chukchi/Bering Sea and Beaufort Sea populations in Alaska are limited. We evaluated aerial line tr
Authors
Lyman L. McDonald, Gerald W. Garner
Modeling variability in replicated surveys at aggregation sites
Surveys of aggregation sites can provide unbiased estimates of annual trends in population size if the proportion of the population counted at these sites does not vary systematically among years. However, counts at these sites tend to be highly variable and resulting trend estimates typically have poor precision. I developed an index based on a simple parametric model for counts of Pacific walrus
Authors
Mark S. Udevitz
Managing Pacific salmon escapements: The gaps between theory and reality
There are myriad challenges to estimating intrinsic production capacity for Pacific salmon populations that are heavily exploited and/or suffering from habitat alteration. Likewise, it is difficult to determine whether perceived decreases in production are due to harvest, habitat, or hatchery influences, natural variation, or some combination of all four. There are dramatic gaps between the true n
Authors
E. Eric Knudsen
One Northwest community - People, salmon, rivers, and the sea: Towards sustainable salmon fisheries
Pacific salmon management is in crisis. Throughout their range, salmon and steelhead populations are being adversely affected by human activities. Without coordinated, effective, and timely action, the future of the Pacific salmon resource is most certainly in doubt. To address the challenges that are currently facing salmon management, concerned citizens representing a diverse array of government
Authors
Donald D. MacDonald, Cleveland R. Steward, E. Eric Knudsen
Populations and productivity of seabirds at South Marble Island, Glacier Bay, Alaska, during May-July, 1999
In the course of directed research on glaucous-winged gulls, we investigated the numbers and activities of all breeding and non-breeding seabirds associated with South Marble Island in Glacier Bay, Alaska, during mid-May to late July, 1999. Most observations were made from the island; additional observations were made during transportation to and from the island. Data were collected on the presenc
Authors
Stephani Zador, John F. Piatt
Setting the stage for a sustainable Pacific salmon fisheries strategy
Salmon and steelhead Oncorhynchus spp., have been keystone species for ecosystems and human cultures of the North American Pacific coast for cons. Yet, in the past century, many populations have been greatly diminished and some are now extinct-the result of a combination of factors, including habitat loss and degradation, overfishing, natural variability in salmon production, negative effects of a
Authors
Donald D. MacDonald, Cleveland R. Steward, E. Eric Knudsen
Changes in proximate composition and somatic energy content for Pacific sand lance (Ammodytes hexapterus) from Kachemak Bay, Alaska relative to maturity and season
Mean dry-weight energy values of adult Pacific sand lance (Ammodytes hexapterus) peaked in spring and early summer (20.91 kJg−1 for males, 21.08 kJg−1 for females), then declined by about 25% during late summer and fall (15.91 kJg−1 for males, 15.74 kJg−1 for females). Late summer declines in energy density paralleled gonadal development. Gender differences in energy density (males<females) were o
Authors
Martin D. Robards, Jill A. Anthony, George A. Rose, John F. Piatt
Biology of the genus Ammodytes, the sand lances
Although much taxonomic confusion exists within the genus Ammodytes, six species are currently recognized: personatus, hexapterus, americanus, dubius, tobianus, and marinus. Sand lance are both euryhaline and eurythermal, as well as tolerant of reduced oxygen concentrations. The absence of a swim bladder allows this narrow, elongate fish to spend much time buried dormant in intertidal and shallow
Authors
Martin D. Robards, John F. Piatt
Data for periphyton and water samples collected from the south Florida ecosystem, 1995 and 1996
This report presents data for samples of periphyton and water collected in 1995 and 1996 from Water Conservation Areas, the Big Cypress National Preserve, and the Everglades National Park in south Florida. Periphyton samples were analyzed for concentrations of total mercury, methylmercury, nitrogen, phosphorus, organic carbon, and inorganic carbon . Water-column samples collected on the same dates
Authors
N.S. Simon, T. Cox, R. Spencer