SEARCH · USGS Science

Results for “Migrant”

Search indexed USGS publications on groundwater, aquifers, geologic maps, mineral resources and earthquakes. Explore source records by subject and place.

SourceResearch connectionFrom yearThrough year

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 523 records · Page 29Linked to original sources

USGS2004

Atlantic Flyway review: Region IV - Fall 2003: Robbins Nest, Laurel, MD (390-0765)

The most notable finding at this station in 2003 was the sharp decline in recaptures of previously banded birds and most especially a Crash in the chickadee and titmouse populations. In the autumn of 2001, I recaptured 36 birds banded in previous autumns, but I caught only 24 returns in 2002 and 17 in 2003, a 33% drop each year. In 2002, Tufted Titmouse was my fourth most common species (19 caught) and Carolina Chickadee (15)was in seventh place. This year, I had only four titmice and six chickadees, declines of 79% and 60%. Until now, only the migratory species have been of concern. We suspect West Nile virus is responsible. However, the oldest bird we recaptured this year was Blue Jay 723-42798, banded as HY in 1993, a species known to be especially vulnerable to West Nile. Half of this year's returns were cardinals, the oldest of which was only four years of age. My birds/100nh continues to drop each year without any noticeable change in surrounding habitat. The only banded migrant known to have remained here for more than a week was a Swainson's Thrush that weighed 31.9 g on 4 Oct and 41.6 g nine days later, an increase of 30%.

Maryland↗

USGS2005

Atlantic Flyway review: Region IV, Piedmont-Coastal Plain, Fall 2004: Robbins Nest, Laurel, MD (390-0765)

The continuing decline in migratory species is depressing. For a 'migration station' to report Northern Cardinal as the species most commonly banded during the autumn months came as a real shock, especially when the cardinal was so far ahead of second-place catbird. I caught twice as many cardinals as all sparrows combined (including juncos), and the total for cardinals came within ten birds of the total for all warblers combined. Warblers comprised only 16.8% of this fall's catch, compared with an average of 21.7% for the previous five years. Hurricanes Bonnie and Frances passed to the east of us and Charles and Ivan to the west, but none was followed by a landfall of migrants. Last year I reported the sharp drop in Tufted Titmice and Carolina Chickadees locally and the small number of returns from prior years. This year, after no overwintering titmice, numbers have returned to nearly normal, but chickadee numbers are still only half normal. I recaptured cardinals from each year back to 1999, but the only other birds more than two years old were a Carolina Wren and two titmice banded in the autumn of 2000.

Maryland↗

USGS2002

Longevity records and survival estimate of birds in a Guatemala rain forest

Birds were mist-netted for ten consecutive 'winter' seasons at two sites on Cerro San Gil and for three to nine seasons at eight other sites on the mountain. Sixteen nets were used at each site for three days; net locations were the same each year. From 1,255 subsequent-year recaptures we computed annual survival using the program MARK. A low annual survival of 0.26+0.03 for Long-tailed Hermit probably reflects extensive wandering in search of food. The only other residents with low survival rates were Ochre-bellied Flycatcher (0.32) and Olive-backed Euphonia (0.38). Other residents tested ranged from 0.49 for Red-capped Manakin to 0.67 for Stub-tailed Spadebill and are within ranges reported from other tropical sites. Rates for migrants were lower, ranging from 0.33 (Worm-eating Warbler) to 0.45 (Kentucky Warbler). Limiting the analysis to known territorial adults (birds that had already returned from a previous year), raised survival rates for residents an average of 0.05, whereas rates for wintering migratory species remained unchanged. The oldest birds recaptured were all residents: Scalythroated Leaftosser (9 years 9 months), Tawny-winged and Wedge-billed Woodcreepers, Northern Bentbill, Tawny-crowned Greenlet, and White-breasted Woodwren (8 years 9 months each). Ages over three years nine months were recorded for 46 species; for the majority of these, new maximum age records were established. A positive relationship was found between survival rate and maximum age and between sample size and maximum age

Program and Abstracts, Association of Field Ornith↗

USGS2007

Current range of the eastern population of Painted Bunting (Passerina ciris). Part II: Winter range

The importance of wintering areas for Neotropical migrants is well established. The wintering range of the eastern population of Painted Bunting (Passerina ciris) is described in detail and presented in maps. The paper also discusses extralimital records from islands in the Caribbean Basin as well as scattered wintering individuals outside the winter range. The possibility of eastern birds wintering on the Yucatan Peninsula and adjacent Central America is considered. An extensive treatment of the protected areas of Peninsular Florida, the northern Bahamas, and Cuba describes the importance of upland habitats within these protected areas for wintering buntings. This information should be useful to land management agencies, conservation organizations, and private landholders for the welfare of the bunting and biodiversity in general and may also be of interest to ornithologists, other biological disciplines, naturalists, and birders.

North American Birds↗

USGS2007

The 1999-2003 Summary of the North American Breeding Bird Survey

Data from the North American Breeding Bird Survey were used to estimate continental and regional changes in bird populations for the 5-yr period 1999-2003 and the 2-yr period 2002-2003. These short-term changes were placed in the context of population trends estimated over the 1966-2003 interval. During 1999-2003, 41% of all species exhibited positive trends over the entire survey area, while 64% of all species exhibited positive change between 2002-2003. The continental and regional percentages of species with positive trends were also analyzed for 12 species groups having shared life-history traits. Survey-wide for the entire survey period, grassland birds exhibited the lowest percentage of increasing species (14%), with their sharpest declines occurring in the West during 1999-2003 (10% increasing). During 1999-2003, short-distance migrants experienced significant declines in all regions, where numbers of species with increasing trends ranged from 22% - 34%. Most species fared well during the 2002-2003 period, with 64% (P < 0.05) increasing survey-wide. This was primarily a result of increases in the Central and Western BBS regions where 21 of 24 species groups exhibited significant increases in the number of species with positive trends.

Bird Populations↗

USGS1989

Habitat area requirements of breeding forest birds of the middle Atlantic states

Conservation of birds requires an understanding of their nesting requirements, including area as well as structural characteristics of the habitat. Previous studies have shown that many neotropical migrant bird species seem to depend on extensive forested areas, but the specific area requirements of individual species have not been clarified sufficiently to aid in design and management of effective preserves. For this 5-year study, bird and vegetation data were obtained at 469 points in forests ranging in area from 0.1 ha to more than 3,000 ha in Maryland and adjacent states. Data were analyzed first by stepwise regression to identify habitat factors that had the greatest influence on relative abundance of each bird species. In the relatively undisturbed mature forests studied, degree of isolation and area were significant predictors of relative abundance for more bird species than were any habitat variables. For species for which forest area was a significant predictor of abundance, we used logistic regression to examine the relationship between forest area and the probability of detecting the species. In managing forest lands for wildlife, top priority should go toward providing for the needs of area-sensitive or rare species rather than increasing species diversity per se. Avian species that occur in small and disturbed forests are generalists that are adapted to survival under edge conditions and need no special assistance from man. Forest reserves with thousands of hectares are required to have the highest probability of providing for the least common species of forest birds in a region. However, if preservation of large contiguous forest tracts is not a realistic option, results of this study suggest 2 alternative approaches. First, if other habitat attributes also are considered, smaller forests may provide suitable breeding sites for relatively rare species. Second, smaller tracts in close proximity to other forests may serve to attract or retain area-sensitive species.

Book↗

USGS1995

Northern Pintail ( Anas acuta )

The Northern Pintail is a medium-sized dabbling duck of slender, elegant lines and conservative plumage coloration. It is circumpolar in distribution and abundant in North America, with core nesting habitat in Alaska and the Prairie Pothole Region of southern Canada and the northern Great Plains. Breeders favor shallow wetlands interspersed throughout prairie grasslands or arctic tundra. An early fall migrant, the species arrives on wintering areas beginning in August, after wing molt, often forming large roosting and feeding flocks on open, shallow wetlands and flooded agricultural fields. The birds consume grains, marsh plant seeds, and aquatic invertebrates throughout the fall and winter. Northern Pintails are among the earliest nesting ducks in North America, beginning shortly after ice-out in many northern areas. Individuals form new pair bonds each winter but are highly promiscuous during the nesting season, with mated and unmated males often involved in vigorous, acrobatic Pursuit Flights. Annual nest success and productivity vary with water conditions, predation, and weather. Females build nests on the ground, often long distances from water. Only the female incubates; her mate leaves shortly after incubation begins. Ducklings hatch together in one day, follow the female to water after a day in the nest, and fledge by July or August. Adults and ducklings consume mainly aquatic invertebrates during the breeding season. Predators and farming operations destroy many thousands of Northern Pintail nests annually; farming has also greatly reduced the amount of quality nesting cover available. Winter habitats are threatened by water shortages, agricultural development, contamination, and urbanization. Periods of extended drought in prairie nesting regions have caused dramatic population declines, usually followed by periods of recovery. Over the long term, however, the continental population of Northern Pintails has declined significantly from 6 million birds in the early 1970s to less than 3 million in the late 1980s and early 1990s. However, new conservation measures, such as habitat restoration and enhancement of agricultural lands, as well as prudent harvest restrictions, suggest that Northern Pintails should have a secure future in North America.

Book chapter↗

USGS1998

Foods of Buller's shearwaters (Puffinus bulleri) associated with driftnet fisheries in the central North Pacific Ocean

We examined digestive tract contents and stable nitrogen isotope ratios (??15N) in breast muscles of Buller's shearwaters (Puffinus bulleri) salvaged from squid and largemesh driftnets in the central North Pacific Ocean. The epipelagic Pacific saury (Cololabis saira) was the predominant prey, making up 71% of prey mass in digestive tracts. The remainder of the diet included small numbers of crustaceans, small fishes, and squids. The high degree of specialization in the diet seems to indicate that in the North Pacific, Buller's Shearwaters usually feed at or near the water surface and rarely pursue food under water. Although these birds have been observed feeding on scraps from fishing vessels, our data suggest that offal comprises less than 10% of the diet. Stable nitrogen isotope values provided quantified information on the timing of arrival of migrants into the North Pacific.

Notornis↗

USGS2000

Heteromorph ammonites from the Upper Campanian (Upper Cretaceous) Baculites cuneatus and Baculites reesidei zones of the Pierre Shale in Colorado, USA

Calcareous sandstone concretions in the Upper Cretaceous Pierre Shale in Middle Park and in the Fort Collins area of Colorado in the U.S. Western Interior contain heteromorph ammonites of the families Nostoceratidae HYATT, 1894, and Diplomoceratidae SPATH, 1926. The following species are described: Nostoceras cf. N. approximans (CONRAD, 1855), Nostoceras cf. N. obtusum HOWARTH, 1965, N. larimerense sp. nov., Nostoceras cf. N. splendidum (SHUMARD, 1861). Didymoceras aurarium sp. nov., D. draconis (STEPHENSON, 1941), Cirroceras conradi (MORTON, 1841), Anaklinoceras minutum sp. nov., Solenoceras texanum (SHUMARD, 1861), Solenoceras cf. S. reesidei STEPHENSON, 1941, Lewyites oronensis (LEWY, 1969), and Lewyites? sp. All these species are migrants from the Gulf coastal region. Didymoceras draconis and Cirroceras conradi are also known from the Delaware-New Jersey area, and these two species, together with Solenoceras texanum are known from as far away as Israel.

Colorado↗

USGS2000

Wildlife tradeoffs based on landscape models of habitat

It is becoming increasingly clear that the spatial structure of landscapes affects the habitat choices and abundance of wildlife. In contrast to wildlife management based on preservation of critical habitat features such as nest sites on a beach or mast trees, it has not been obvious how to incorporate spatial structure into management plans. We present techniques to accomplish this goal. We used multiscale logistic regression models developed previously for neotropical migrant bird species habitat use in South Carolina (USA) as a basis for these techniques. Based on these models we used a spatial optimization technique to generate optimal maps (probability of occurrence, P = 1.0) for each of seven species. To emulate management of a forest for maximum species diversity, we defined the objective function of the algorithm as the sum of probabilities over the seven species, resulting in a complex map that allowed all seven species to coexist. The map that allowed for coexistence is not obvious, must be computed algorithmically, and would be difficult to realize using rules of thumb for habitat management. To assess how management of a forest for a single species of interest might affect other species, we analyzed tradeoffs by gradually increasing the weighting on a single species in the objective function over a series of simulations. We found that as habitat was increasingly modified to favor that species, the probability of presence for two of the other species was driven to zero. This shows that whereas it is not possible to simultaneously maximize the likelihood of presence for multiple species with divergent habitat preferences, compromise solutions are possible at less than maximal likelihood in many cases. Our approach suggests that efficiency of habitat management for species diversity can by maximized for even small landscapes by incorporating spatial context. The methods we present are suitable for wildlife management, endangered species conservation, and nature reserve design.

Conference Paper↗

USGS2002

Temperature history of Coregonus artedi in the St. Marys River, Laurentian Great Lakes, inferred from oxygen isotopes in otoliths

The population of Coregonus artedi in the St. Marys River, between lakes Superior and Huron, was sampled and otoliths were analyzed for oxygen isotopic composition to determine whether the fish are residents in the St. Marys River and its warm bays or migrants to and from cold Lake Huron. Otoliths were extracted, sectioned, and growth ring-specific samples of calcium carbonate were milled to obtain samples for determination of oxygen isotope ratios (18O values). The 18O values of calcium carbonate (CaCO3) in accretionary structures such as otoliths allow calculation of growth temperatures of the fish, because of differential fractionation of oxygen isotopes at different temperatures. Growth temperatures of 10 St. Marys River lake herring were compared with lake and catch data as well as growth temperatures of lake herring collected from Lake Huron and other ciscoes from the Great Lakes. Results of this analysis indicate that these fish remained in the bays of the St. Marys River for their entire life history. After their second year they grew at average temperatures between 11 C and 13 C, consistent with temperature in the warmer bays of the St. Marys River and 6 C higher than expected for growth of this species in Lake Huron.

St. Marys River↗

USGS2002

Accessible habitat for shorebirds: Factors influencing its availability and conservation implications

We examined the relationship between water levels and accessible habitat, and how accessible habitat influenced Dunlin (Calidris alpina) and Semipalmated Sandpiper (Calidris pusilla) numbers in managed wetlands at Pea Island (North Carolina) and Merritt Island (Florida) National Wildlife Refuges in 1998 and 1999. At Pea Island we experimentally manipulated water levels, which also allowed us to examine the effects of water level fluctuations on prey base. We examined these relationships because access to foraging habitat by shorebirds is positively related to the length of their tarsometatarsus, and in the southeastern United States, small calidrids are a numerically important component of the two million migrants using inland and managed wetlands. We confirmed the importance of shallow waters for Dunlin and Semipalmated Sandpiper-numbers increased with increasing availability of 0-4 cm habitat. At Merritt Island, Dunlin use was inversely related to variability in water depth of 0-4 cm. Minimizing the frequency and amplitude of water level fluctuations associated with single-capped culverts is necessary to improve habitat quality. After adjusting for accessibility, spring habitat requirements for Dunlin and Semipalmated Sandpiper at Pea Island were met under nearly all abundance scenarios. We identified water level targets that maximize accessible habitat at Pea Island. In contrast, winter habitat requirements for Dunlin at Merritt Island were not met except in one scenario. Seasonally low prey density contributed to the shortfall, suggesting that allocating more habitat is the primary management option. Manipulating water levels at Pea Island did not adversely affect the density of eight shorebird prey species. Estimates of accessible habitat and other parameters (e.g., turnover rates, prey biomass) are essential to set and implement realistic shorebird habitat conservation goals.

Waterbirds↗

USGS2002

Records of Northern Mockingbird, Mimus polyglottos, occurrences in North Dakota during the twentieth century

The Northern Mockingbird (Mimus polyglottos) is a common bird in the southern United States that has been expanding its breeding range into the northern United States and southern Canada. During the twentieth century, there were 128 reports of Northern Mockingbird occurrences in North Dakota, including 106 reports during the breeding season (15 April to 31 August) and 22 during the nonbreeding season (1 September to 14 April). The species has been largely absent from North Dakota from January through mid-April. Prior to the 1930s, there was only one record (1916) of the Northern Mockingbird in the state. Observations of Northern Mockingbirds in North Dakota increased markedly between the 1930s and 1990s. On average, there were 0.3 reports of mockingbirds per year in 1931-1940, 0.6 in 1941-1950, 1.1 in 1951-1960, 1.6 in 1961-1970, 2.4 in 1971-1980, 2.3 in 1981-1990, and 4.5 in 1991-2000. The species has been observed in North Dakota nearly annually since 1958. At least six reports during the twentieth century included evidence of nesting (nests or dependent young). Based on mockingbird records during the twentieth century, we designate the current status of the Northern Mockingbird in North Dakota as a rare spring migrant, rare summer visitant, casual nester, and a casual fall and winter visitant.

Canadian Field-Naturalist↗

USGS2003

Seasonal movements, migratory behavior, and site fidelity of West Indian manatees along the Atlantic coast of the United States

The West Indian manatee ( Trichechus manatus ) is endangered by human activities throughout its range, including the U.S. Atlantic coast where habitat degradation from coastal development and manatee deaths from watercraft collisions have been particularly severe. We radio-tagged and tracked 78 manatees along the east coast of Florida and Georgia over a 12-year period (1986-1998). Our goals were to characterize the seasonal movements, migratory behavior, and site fidelity of manatees in this region in order to provide information for the development of effective conservation strategies. Most study animals were tracked remotely with the Argos satellite system, which yielded a mean (SD) of 3.7 (1.6) locations per day; all were regularly tracked in the field using conventional radiotelemetry methods. The combined data collection effort yielded >93,000 locations over nearly 32,000 tag-days. The median duration of tracking was 8.3 months per individual, but numerous manatees were tracked over multiple years (max = 6.8 years). Most manatees migrated seasonally over large distances between a northerly warm-season range and a southerly winter range (median one-way distance = 280 km, max = 830 km), but 12% of individuals were resident in a relatively small area (<50 km) year-round. The movements of one adult male spanned >2,300 km of coastline between southeastern Florida and Rhode Island. No study animals journeyed to the Gulf coast of Florida. Regions heavily utilized by tagged manatees included: Fernandina Beach, FL to Brunswick, GA in the warm season; northern Biscayne Bay to Port Everglades, FL in the winter; and central coastal Florida, especially the Banana River and northern Indian River lagoons, in all seasons. Daily travel rate, defined as the distance between successive mean daily locations, averaged 2.5 km (SD = 1.7), but this varied with season, migratory pattern, and sex. Adult males traveled a significantly greater distance per day than did adult females for most of the warm season, which corresponded closely with the principal period of breeding activity, but there was no difference between the sexes in daily travel rate during the winter. The timing of seasonal migrations differed markedly between geographic regions. Most long-distance movements in the southern half of the study area occurred between November and March in response to changing temperatures, whereas most migrations in the northern region took place during the warmer, non-winter months. Manatees left their warm-season range in central Florida in response to cold fronts that dropped water temperatures by an average of 2.0??C over the 24-hr period preceding departure. Water temperature at departure from the warm-season range averaged 19??C, but varied among individuals (16-22??C) and was not related to body size or female reproductive status. The presence of industrial warm-water effluents permitted many manatees to overwinter north of their historic winter range, and for some migrants this delayed autumn migrations and facilitated earlier spring migrations. Southward autumn and northward spring migrations lasted an average of 10 and 15 days at mean rates of 33.5 (SD = 7.6) and 27.3 (SD = 10.5) km/day, respectively. The highest rate of travel during migration was 87 km/day (3.6 km/hr) during winter. Manatees overwintering in southeastern Florida often traveled north during mild weather - sometimes reaching their warm-season range - only to return south again with the next major cold front. Manatees were consistent in their seasonal movement patterns across years and showed strong fidelity, to warm-season and winter ranges. Within a season, individuals usually occupied only 1 or 2 core use areas that encompassed about 90% of daily locations. Most manatees returned faithfully to the same seasonal ranges year after year (median distance between range centers was <5 km between years). Seasonal movements of 4 immature manatees tracked as calves with their mothers

Florida, Georgia↗

USGS2004

Spawning ecology of finespotted Snake River cutthroat trout in spring streams of the Salt River valley, Wyoming

We studied spawning ecology of cutthroat trout (Oncorhynchus clarki) in streams that originate as springs along the Salt River, a Snake River tributary in western Wyoming. We assessed (1) relative numbers of upstream-migrant and resident adults present during the spawning period in spring streams, (2) influence of habitat modification on use of spring streams for spawning, and (3) habitat features used for spawning in spring streams. Four spring streams were studied, 2 with substantial modification to enhance trout habitat and 2 with little or no modification. Modifications consisted primarily of constructing alternating pools and gravel-cobble riffles. Only a small portion of adult fish in spring streams during the spawning period had migrated upstream from the Salt River between March and the middle of June. Larger numbers of adult fish and more redds were observed in the 2 modified streams compared with the 2 streams with little or no modification. Most spawning occurred on constructed riffles with small gravel and over a narrow range of depths and velocities. Cutthroat trout, rainbow trout (Oncorhynchus mykiss), and their hybrids were observed in 1 stream with habitat modifications, indicating that measures to halt invasion by rainbow trout, as well as habitat improvement, are needed to preserve this native trout within the Salt River valley.

Western North American Naturalist↗

USGS2009

Use of non-natal estuaries by migratory striped bass (Morone saxatilis) in summer

For most migratory fish, little is known about the location and size of foraging areas or how long individuals remain in foraging areas, even though these attributes may affect their growth, survival, and impact on local prey. We tested whether striped bass (Morone saxatilis Walbaum), found in Massachusetts in summer, were migratory, how long they stayed in non-natal estuaries, whether observed spatial patterns differed from random model predictions, whether fish returned to the same area across multiple years, and whether fishing effort could explain recapture patterns. Anchor tags were attached to striped bass that were caught and released in Massachusetts in 1999 and 2000, and recaptured between 1999 and 2007. In fall, tagged striped bass were caught south of where they were released in summer, confirming that fish were coastal migrants. In the first summer, 77% and 100% of the recaptured fish in the Great Marsh and along the Massachusetts coast, respectively, were caught in the same place where they were released. About two thirds of all fish recaptured near where they were released were caught 2-7 years after tagging. Our study shows that smaller (400-500 mm total length) striped bass migrate hundreds of kilometers along the Atlantic Ocean coast, cease their mobile lifestyle in summer when they use a relatively localized area for foraging (<20 km 2 ), and return to these same foraging areas in subsequent years.

Fishery Bulletin↗

USGS2013

Snake River fall Chinook salmon life history investigations: Annual report 2011 (April 2011 - March 2012)

Executive Summary Chapter One – This chapter was published in the Transactions of the American Fisheries Society in 2012. We conducted a three-year radiotelemetry study in the lower Snake River to answer the questions: do fall Chinook salmon juveniles pass dams during winter when bypass systems and structures designed to prevent mortality are not operated; does downstream movement rate vary annually, seasonally, and from reservoir to reservoir; and, what are some of the factors that contribute to annual, seasonal, and spatial variation in downstream movement rate? Fall Chinook salmon juveniles moved downstream up to 169 km and fast enough (7.5 km/d) such that large percentages (up to 93%) of the fish passed one or more dams during winter. Mean downstream movement rate varied annually (9.2-11.3 km/d), increased from winter (7.5 km/d) to spring (16.4 km/d), and increased (6.9-16.8 km/d) as fish moved downstream from reservoir to reservoir. Fish condition factor at tagging explained some of the annual variation ( P ≤ 0.01) in downstream movement rate, whereas water particle velocity ( P ≤0.0001) and temperature ( P ≤0.0001) explained portions of the seasonal variation. An increase in migrational disposition as fish moved downstream helped explain the spatial variation ( P =0.05-0.07). The potential cost of winter movement might be reduced survival due to turbine passage when the bypass systems and spillway passage structures are not operated. Efforts to understand and increase passage survival of winter migrants in large impoundments might help to rehabilitate some imperiled anadromous salmonid populations. Chapter Two – Natural juvenile fall Chinook salmon in the Snake and Clearwater rivers exhibit two life history strategies. “Ocean-type” fish migrate out to the ocean in their first summer of life as subyearlings, but “reservoir-type” fish delay seaward migration during the summer, and some overwinter in reservoirs before continuing their migration the following spring as yearlings. Earlier emerging fish produced in the Snake River tend to adopt the ocean-type life history whereas many of the later emerging fish from the Clearwater River tend to adopt the reservoirtype life history. The underlying cause of the reservoir-type life history is poorly understood, but we believe there may be link to physiological development. We used traditional markers of the parr-smolt transformation (smoltification), including gill Na + /K + -ATPase activity and thyroid hormone levels, along with gene expression microarrays to assess the development of ocean-type juvenile fall Chinook salmon and then compared it to that of juvenile fall Chinook salmon from the Clearwater River. We showed that parr in the Snake River are physiologically distinct from actively-migrating smolts but smolts migrating early and late in the summer and fall are physiologically similar. Juvenile fall Chinook salmon collected from the Clearwater River were similar in size to early-migrating smolts in the Snake River but were most physiologically similar to Snake River parr. Genes differentially expressed between Snake River parr and smolts and between fish from the Clearwater River and smolts from the Snake River were involved in the cell cycle, steroid metabolism and other metabolic pathways, and DNA repair and packaging. Many of the genes differentially expressed in these comparisons had expression patterns that correlated with gill Na + /K + -ATPase activity, suggesting that they were related to smoltification and migration status. Chapter Three – Natural subyearlings produced in the Clearwater River are exposed to cool (~10-12°C) temperatures when water is released from Dworshak Reservoir for summer flow augmentation. Total dissolved gas (TDG) levels range from 100-110% in the lower Clearwater iv River. When fish move into the Snake River, they encounter temperatures up to 24°C at the surface which have the potential to incur gas bubble disease (GBD) in fish as dissolved gases in their bodies expand under warmer temperatures. This may result in both direct and indirect mortality, but this situation has been little studied. We conducted laboratory experiments to examine subyearling mortality rates and incidence and severity of GBD in fish that were moved between waters that varied in TDG and temperature. Fish experienced significant mortality only at temperatures of 25°C, which increased with exposure time. However there was no significance difference in mortality between fish acclimated to 100% TDG and 110% TDG. Fish that died did show signs of GBD. Generally, signs of GBD such as bubbles in the lateral line and unpaired fins were higher in fish acclimated at 110% TDG than in fish acclimated at 100% TDG, but there were few trends related to exposure temperature. Field measurements of TDG showed that TDG ranged from about 100% to 122.5% at some locations. Generally, TDG fluctuated daily, up to 8% during August and early September, and was highest late in the afternoon and lowest in the early morning. Laboratory results and field monitoring demonstrated that emigrating juvenile salmon can potentially be at risk from elevated temperatures, TDG, and GBD albeit to an unknown extent, which may increase their vulnerability to predation. Chapter Four – We conducted monthly beam trawling in Lower Granite and Little Goose reservoirs to describe the seasonal abundance of benthic epifauna that are potentially important as prey to juvenile fall Chinook salmon. The predominant taxa collected were Siberian prawns, the opossum shrimp Neomysis mercedis , and the amphipod Corophium sp. Prawns were relatively abundant at shallow sites in both reservoirs in June, but were more abundant at deep sites in lower and middle reservoir reaches in autumn. Prawn densities were commonly <0.2/m2. Prawn length-frequency data indicated that there were at least two size classes. Juvenile prawns present in shallow water more often than adult prawns, which were generally only found in deep water by autumn. Ovigerous prawns had an average of 171 eggs, which represented about 11.5% of their body weight. Limited diet analyses suggested that prawns consumed Corophium , Neomysis , and aquatic insects. Neomysis dominated all catches both in terms of abundance and biomass, and they were more abundant in Lower Granite compared to Little Goose reservoir. Neomysis were more abundant at shallow sites than at deep sites. Corophium were present in our collections but were never abundant, probably because our trawl was not effective at capturing them. The caloric content of prawns (4,782 Kcal), Neomysis (4,962 Kcal), and Corophium (4,926 Kcal) indicates that these prey would be energetically profitable for juvenile salmon. Subyearling fall Chinook salmon prey heavily on Neomysis and Corophium at times, but the importance of prawns as prey is uncertain.

Oregon, Washington↗

USGS2010

Snake River Fall Chinook Salmon life history investigations annual report, 2009

In 2009, we used radio and acoustic telemetry to evaluate the migratory behavior, survival, mortality, and delay of subyearling fall Chinook salmon in the Clearwater River and Lower Granite Reservoir. We released a total of 1,000 tagged hatchery subyearlings at Cherry Lane on the Clearwater River in mid August and we monitored them as they passed downstream through various river and reservoir reaches. Survival through the free-flowing river was high (>0.85) for both radio- and acoustic-tagged fish, but dropped substantially as fish delayed in the Transition Zone and Confluence areas. Estimates of the joint probability of migration and survival through the Transition Zone and Confluence reaches combined were similar for both radio- and acoustic-tagged fish, and ranged from about 0.30 to 0.35. Estimates of the joint probability of delaying and surviving in the combined Transition Zone and Confluence peaked at the beginning of the study, ranging from 0.323 (SE =NA; radio-telemetry data) to 0.466 (SE =0.024; acoustic-telemetry data), and then steadily declined throughout the remainder of the study. By the end of October, no live tagged juvenile salmon were detected in either the Transition Zone or the Confluence. As estimates of the probability of delay decreased throughout the study, estimates of the probability of mortality increased, as evidenced by the survival estimate of 0.650 (SE =0.025) at the end of October (acoustic-telemetry data). Few fish were detected at Lower Granite Dam during our study and even fewer fish passed the dam before PIT-tag monitoring ended at the end of October. Five acoustic-tagged fish passed Lower Granite Dam in October and 12 passed the dam in November based on detections in the dam tailrace; however, too few detections were available to calculate the joint probabilities of migrating and surviving or delaying and surviving. Estimates of the joint probability of migrating and surviving through the reservoir was less than 0.2 based on acoustic-tagged fish. Migration rates of tagged fish were highest in the free-flowing river (median range = 36 to 43 km/d) but were generally less than 6 km/d in the reservoir reaches. In particular, median migration rates of radio-tagged fish through the Transition Zone and Confluence were 3.4 and 5.2 km/d, respectively. Median migration rate for acoustic-tagged fish though the Transition Zone and Confluence combined was 1 km/d. We radio tagged 84 smallmouth bass and six channel catfish in the Confluence reach and later detected 48 bass and 1 catfish during mobile tracking. Predators were primarily located along shorelines in the Confluence, but a couple of smallmouth bass did swim into the Clearwater River. Most radio-tagged subyearlings that we determined to be dead were also located in shoreline areas suggesting that predation could account for some of the mortality we observed. Our total dissolved gas (TDG) monitoring in the lower Clearwater River showed a cyclic pattern of low (~102%) TDG in the morning and higher (~110%) TDG in the late afternoon. Using a compensation depth of 1 m, we found that 15.4% (3.9 ha) of the lower 13 km of the Clearwater River would not provide fish with an opportunity for depth compensation in a low flow year. Water temperatures in the Clearwater River showed diel variations of about 2°C, and generally ranged from 10-12°C during summer flow augmentation. The Clearwater River generally showed little thermal variation while our tagged fish were at large, whereas the Snake River at the downstream boundary of the Confluence was thermally heterogeneous until mid-September. In the unimpounded Clearwater River, simulated water velocities ranged from about 1.3 to 1.5 m/s before flow augmentation ended, and were about 0.6 m/s thereafter. By comparison, velocities at the Clearwater River mouth were about 0.3 m/s during flow augmentation, and about 0.1 m/s thereafter. From October 2008 to February 2009 and from July 2009 to March 2010 we used monthly mobile hydroacoustic surveys to estimate the number of juvenile Chinook salmon in Little Goose and Lower Granite reservoirs, the first two reservoirs encountered on the lower Snake River by downstream migrants. Concurrent lampara seining was used to verify acoustic targets, calculate condition factors, and to examine spatial and temporal density patterns. Our data indicated that holdovers are larger in warmer water temperature years and smaller in colder water temperature years. Lampara catch data indicated that holdovers were seasonally the most abundant and in the best condition in November and December, whereas the hydroacoustic data showed population peaks in October in Lower Granite Reservoir and in January in Little Goose Reservoir. Maximum population estimates in Lower Granite Reservoir were 6,929 in October 2008 and 7,218 in October 2009. In Little Goose Reservoir, maximum population estimates were 9,645 in January 2009 and 10,419 in January 2010. By February, abundances and relative condition factors decreased as most holdovers had probably moved past Lower Granite and Little Goose dams. Spatial differences were primarily longitudinal with greater holdover abundances in the lower reaches of both reservoirs.

Report↗