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At least 505 records · Page 28Linked to original sources
USGS2004

Migration and stopover strategies of individual Dunlin along the Pacific coast of North America

We radio-marked 18 Dunlin, Calidris alpina (L., 1758), at San Francisco Bay, California, and 11 Dunlin at Grays Harbor, Washington, and relocated 90% of them along the 4200 km long coastline from north of San Francisco Bay to the Yukon-Kuskokwim Delta, Alaska. The Copper River Delta, Alaska, was the single most important stopover site, with 79% of the marked birds detected there. Our second most important site was the Willapa Bay and Grays Harbor complex of wetlands in Washington. The mean length of stay past banding sites ranged from 1.0 to 3.8 days. Controlling for date of departure, birds banded at San Francisco Bay had higher rates of travel to the Copper River Delta than those banded at Grays Harbor. The later a bird left a capture site, the faster it traveled to the Copper River Delta. Length of stay at the Copper River Delta was inversely related to arrival date. We did not find any effect of sex on travel rate or length of stay. Combining the results of this study with our previous work on Western Sandpipers, Calidris mauri (Cabanis, 1875), reveals variation of migration strategies used within and among shorebird species along the eastern Pacific Flyway. ?? 2004 NRC.

Canadian Journal of Zoology↗
USGS2018

An intercomparison of oceanic methane and nitrous oxide measurements

Large-scale climatic forcing is impacting oceanic biogeochemical cycles and is expected to influence the water-column distribution of trace gases, including methane and nitrous oxide. Our ability as a scientific community to evaluate changes in the water-column inventories of methane and nitrous oxide depends largely on our capacity to obtain robust and accurate concentration measurements that can be validated across different laboratory groups. This study represents the first formal international intercomparison of oceanic methane and nitrous oxide measurements whereby participating laboratories received batches of seawater samples from the subtropical Pacific Ocean and the Baltic Sea. Additionally, compressed gas standards from the same calibration scale were distributed to the majority of participating laboratories to improve the analytical accuracy of the gas measurements. The computations used by each laboratory to derive the dissolved gas concentrations were also evaluated for inconsistencies (e.g., pressure and temperature corrections, solubility constants). The results from the intercomparison and intercalibration provided invaluable insights into methane and nitrous oxide measurements. It was observed that analyses of seawater samples with the lowest concentrations of methane and nitrous oxide had the lowest precisions. In comparison, while the analytical precision for samples with the highest concentrations of trace gases was better, the variability between the different laboratories was higher: 36 % for methane and 27 % for nitrous oxide. In addition, the comparison of different batches of seawater samples with methane and nitrous oxide concentrations that ranged over an order of magnitude revealed the ramifications of different calibration procedures for each trace gas. Finally, this study builds upon the intercomparison results to develop recommendations for improving oceanic methane and nitrous oxide measurements, with the aim of precluding future analytical discrepancies between laboratories.

Biogeosciences↗
USGS1987

The Japan Trench and its juncture with the Kuril Trench: cruise results of the Kaiko project, Leg 3

This paper presents the results of a detailed survey combining Seabeam mapping, gravity and geomagnetic measurements as well as single-channel seismic reflection observations in the Japan Trench and the juncture with the Kuril Trench during the French-Japanese Kaiko project (northern sector of the Leg 3) on the R/V “Jean Charcot”. The main data acquired during the cruise, such as the Seabeam maps, magnetic anomalies pattern, and preliminary interpretations are discussed. These new data cover an area of 18,000 km 2 and provide for the first time a detailed three-dimensional image of the Japan Trench. Combined with the previous results, the data indicate new structural interpretations. A comparative study of Seabeam morphology, single-channel and reprocessed multichannel records lead to the conclusion that along the northern Japan Trench there is little evidence of accretion but, instead, a tectonic erosion of the overriding plate. The tectonic pattern on the oceanic side of the trench is controlled by the creation of new normal faults parallel to the Japan Trench axis, which is a direct consequence of the downward flexure of the Pacific plate. In addition to these new faults, ancient normal faults trending parallel to the N65° oceanic magnetic anomalies and oblique to the Japan trench axis are reactivated, so that two directions of normal faulting are observed seaward of the Japan Trench. Only one direction of faulting is observed seaward of the Kuril Trench because of the parallelism between the trench axis and the magnetic anomalies. The convergent front of the Kuril Trench is offset left-laterally by 20 km relative to those of the Japan Trench. This transform fault and the lower slope of the southernmost Kuril Trench are represented by very steep scarps more than 2 km high. Slightly south of the juncture, the Erimo Seamount riding on the Pacific plate, is now entering the subduction zone. It has been preceded by at least another seamount as revealed by magnetic anomalies across the landward slope of the trench. Deeper future studies will be necessary to discriminate between the two following hypothesis about the origin of the curvature between both trenches: Is it due to the collision of an already subducted chain of seamounts? or does it correspond to one of the failure lines of the America/Eurasia plate boundary?

Earth and Planetary Science Letters↗
USGS2012

Cryptic extinction of a common Pacific lizard Emoia impar (Squamata, Scincidae) from the Hawaiian Islands.

Most documented declines of tropical reptiles are of dramatic or enigmatic species. Declines of widespread species tend to be cryptic. The early (1900s) decline and extinction of the common Pacific skink Emoia impar from the Hawaiian Islands is documented here through an assessment of literature, museum vouchers and recent fieldwork. This decline appears contemporaneous with the documented declines of invertebrates and birds across the Hawaiian Islands. A review of the plausible causal factors indicates that the spread of the introduced big-headed ant Pheidole megacephala is the most likely factor in this lizard decline. The introduction and spread of a similar skink Lampropholis delicata across the islands appears to temporally follow the decline of E. impar , although there is no evidence of competition between these species. It appears that L. delicata is spreading to occupy the niche vacated by the extirpated E. impar . Further confusion exists because the skink E. cyanura , which is very similar in appearance to E. impar , appears to have been introduced to one site within a hotel on Kaua'i and persisted as a population at that site for approximately 2 decades (1970s–1990s) but is now also extirpated. This study highlights the cryptic nature of this early species extinction as evidence that current biogeographical patterns of non-charismatic or enigmatic reptiles across the Pacific may be the historical result of early widespread invasion by ants. Conservation and restoration activities for reptiles in the tropical Pacific should consider this possibility and evaluate all evidence prior to any implementation.

Hawai'i↗
USGS2014

Molecular identification of erythrocytic necrosis virus (ENV) from the blood of Pacific herring ( Clupea pallasii )

Viral erythrocytic necrosis (VEN) is a condition affecting the red blood cells of more than 20 species of marine and anadromous fishes in the North Atlantic and North Pacific Oceans. Among populations of Pacific herring ( Clupea pallasii ) on the west coast of North America the disease causes anemia and elevated mortality in periodic epizootics. Presently, VEN is diagnosed by observation of typical cytoplasmic inclusion bodies in stained blood smears from infected fish. The causative agent, erythrocytic necrosis virus (ENV), is unculturable and a presumed iridovirus by electron microscopy. In vivo amplification of the virus in pathogen-free laboratory stocks of Pacific herring with subsequent virus concentration, purification, DNA extraction, and high-throughput sequencing were used to obtain genomic ENV sequences. Fragments with the highest sequence identity to the family Iridoviridae were used to design four sets of ENV-specific polymerase chain reaction (PCR) primers. Testing of blood and tissue samples from experimentally and wild infected Pacific herring as well as DNA extracted from other amphibian and piscine iridoviruses verified the assays were specific to ENV with a limit of detection of 0.0003 ng. Preliminary phylogenetic analyses of a 1448 bp fragment of the putative DNA polymerase gene supported inclusion of ENV in a proposed sixth genus of the family Iridoviridae that contains other erythrocytic viruses from ectothermic hosts. This study provides the first molecular evidence of ENV's inclusion within the Iridoviridae family and offers conventional PCR assays as a means of rapidly surveying the ENV-status of wild and propagated Pacific herring stocks.

Veterinary Microbiology↗
USGS2016

Lake oxygen isotopes as recorders of North American Rocky Mountain hydroclimate: Holocene patterns and variability at multi-decadal to millennial time scales

Lake sediment oxygen isotope records (calcium carbonate-δ 18 O) in the western North American Cordillera developed during the past decade provide substantial evidence of Pacific ocean–atmosphere forcing of hydroclimatic variability during the Holocene. Here we present an overview of 18 lake sediment δ 18 O records along with a new compilation of lake water δ 18 O and δ 2 H that are used to characterize lake sediment sensitivity to precipitation-δ 18 O in contrast to fractionation by evaporation. Of the 18 records, 14 have substantial sensitivity to evaporation. Two records reflect precipitation-δ 18 O since the middle Holocene, Jellybean and Bison Lakes, and are geographically positioned in the northern and southern regions of the study area. Their comparative analysis indicates a sequence of time-varying north–south precipitation-δ 18 O patterns that is evidence for a highly non-stationary influence by Pacific ocean–atmosphere processes on the hydroclimate of western North America. These observations are discussed within the context of previous research on North Pacific precipitation-δ 18 O based on empirical and modeling methods. The Jellybean and Bison Lake records indicate that a prominent precipitation-δ 18 O dipole (enriched-north and depleted-south) was sustained between ~ 3.5 and 1.5 ka, which contrasts with earlier Holocene patterns, and appears to indicate the onset of a dominant tropical control on North Pacific ocean–atmosphere dynamics. This remains the state of the system today. Higher frequency reversals of the north–south precipitation-δ 18 O dipole between ~ 2.5 and 1.5 ka, and during the Medieval Climate Anomaly and the Little Ice Age, also suggest more varieties of Pacific ocean–atmosphere modes than a single Pacific Decadal Oscillation (PDO) type analogue. Results indicate that further investigation of precipitation-δ 18 O patterns on short (observational) and long (Holocene) time scales is needed to improve our understanding of the processes that drive regional precipitation-δ 18 O responses to Pacific ocean–atmosphere variability, which in turn, will lead to a better understanding of internal Pacific ocean–atmosphere variability and its response to external climate forcing mechanisms.

North American Rocky Mountain↗
USGS2006

Probabilistic analysis of tsunami hazards

Determining the likelihood of a disaster is a key component of any comprehensive hazard assessment. This is particularly true for tsunamis, even though most tsunami hazard assessments have in the past relied on scenario or deterministic type models. We discuss probabilistic tsunami hazard analysis (PTHA) from the standpoint of integrating computational methods with empirical analysis of past tsunami runup. PTHA is derived from probabilistic seismic hazard analysis (PSHA), with the main difference being that PTHA must account for far-field sources. The computational methods rely on numerical tsunami propagation models rather than empirical attenuation relationships as in PSHA in determining ground motions. Because a number of source parameters affect local tsunami runup height, PTHA can become complex and computationally intensive. Empirical analysis can function in one of two ways, depending on the length and completeness of the tsunami catalog. For site-specific studies where there is sufficient tsunami runup data available, hazard curves can primarily be derived from empirical analysis, with computational methods used to highlight deficiencies in the tsunami catalog. For region-wide analyses and sites where there are little to no tsunami data, a computationally based method such as Monte Carlo simulation is the primary method to establish tsunami hazards. Two case studies that describe how computational and empirical methods can be integrated are presented for Acapulco, Mexico (site-specific) and the U.S. Pacific Northwest coastline (region-wide analysis).

Natural Hazards↗
USGS2025

Food web structure of the Lake Superior fish community in 2021–2022

The trophic linkages and ecological requirements of the Lake Superior fish community have not been assessed on a whole lake scale in over a decade. Here, we investigated the trophic dynamics across multiple species and habitat zones of Lake Superior. From April to October of 2021 and 2022, a total of five piscivore, four planktivore, and six benthivore species were collected by region and length class during bottom-trawl, standard gillnet, commercial cisco gillnet, and recreational angler surveys. To assess trophic linkages, stomach contents were measured to estimate biomass consumed and a multivariate analysis was used to assess diet composition by species, length, and region. We found a high degree of interconnectedness in the Lake Superior food web, with Mysis as a critical diet item for most fishes. Native piscivore diets varied by region and with ontogeny. Lake charr were important habitat couplers in the lake, exhibiting a diverse diet and opportunistic foraging strategy. Conversely, Pacific salmon were more restricted in their foraging. Planktivores and benthivores primarily consumed Mysis , with less reliance on Diporeia compared to previous studies. Lake whitefish and cisco were the exception to this pattern, with broader bathymetric depth distributions represented in their diets. We found the food web to be supported by a predominantly native species assemblage, with redundancies at all trophic levels.

Lake Superior↗
USGS2022

Seismic evidence for magmatic underplating along the Kodiak-Bowie Seamount Chain, Gulf of Alaska

Oceanic crust formed at mid-ocean ridges may be later modified by off-ridge magmatism forming seamounts, guyots, and islands. We investigate processes associated with seamount formation in the Gulf of Alaska Seamount Province using two coincident seismic reflection/wide-angle profiles. A north-south profile crosses the Kodiak-Bowie Seamount Chain and Aja fracture zone (FZ), and an orthogonal east-west profile is located about 90 km south of the seamount chain over Pacific plate oceanic crust. Structure along the profile away from the seamount chain is consistent with typical oceanic crust. Crust in our study region is thinnest (about 5.6 km) at the Aja FZ. Unlike observations from active transform faults, no low-velocity anomaly is observed at the Aja FZ suggesting that the crustal velocities have recovered to normal values through crack closure and crack healing. Higher lower crustal velocities (∼7.3 and > 7.5 km/s) and thicker crust (∼8.5 and ∼7.0 km) are observed near the Pratt and Durgin Seamounts and at the intersection of the Kodiak-Bowie Seamount Chain linear trend, respectively. These observations are attributed to magmatic underplating associated with seamount province magmatism. Lithospheric thickness variations across the Aja FZ may form a barrier or impediment to magmatic flow. The thickest crust (8.5 km) along our two profiles is located on the younger side of the FZ, and we suggest that the majority of magmatism jumped south of the Aja FZ when thinner lithosphere was encountered by the Bowie hot spot. The crustal structure near the Kodiak-Bowie Seamount Chain is most similar to that of other seamounts and guyots that formed on similarly young lithosphere (8–12 Ma). Our results suggest that lithospheric thickness at the time of hot spot interaction has a large control on magmatic underplating at seamounts and seamount provinces.

Alaska↗
USGS2024

Earthquake relocations delineate discrete a fault network and deformation corridor throughout Southeast Alaska and Southwest Yukon

Deformation in southeastern Alaska and southwest Yukon is governed by the subduction and translation of the Pacific-Yakutat plates relative to the North American plate in the St. Elias region. Despite notable historical seismicity and major regional faults, studies of the region between the Fairweather and Denali faults are complicated by glacial coverage and the remote setting. In the last decade, significant improvements have been made to the density of regional broadband seismometer networks. We relocate more than 5,000 earthquakes between 2010 and 2021 in the region of southeastern Alaska and southwestern Yukon utilizing these improved seismic networks. With reductions in catalog uncertainty, particularly in depth, we quantify the thickness of the seismogenic layer in the crust throughout the region and locate seismicity on a shallow network of upper-crustal faults. Relocated earthquakes, combined with an updated focal-mechanism catalog, permit estimating and classifying motion of active faults. This includes mapping the Totschunda-Fairweather “Connector” fault, which plays an important role in explaining regional deformation, and identifying new faults like the Kathleen Lake fault. We draw similarities between our seismic observations and simplified conceptual models of regional tectonics, which describe a dominant transpressional regime and localized slip partitioning. Our results support a hypothesis where current deformation is taking place on a well-defined and evolved network of shallow faults in the corridor between the Totschunda-Fairweather “Connector” and Denali faults.

Alaska, Yukon↗
USGS2012

Detection of a locked zone at depth on the Parkfield, California, segment of the San Andreas fault

The Parkfield, California, segment of the San Andreas fault is transitional in character between the creeping segment of the fault to the northwest and the locked Carrizo Plain segment to the southeast. The rate of shallow fault slip decreases from 25–30 mm/yr northwest of the epicenter of the 1966 Parkfield earthquake to zero at the southeastern end of the 1966 rupture zone. Data from a network of trilateration lines spanning the San Andreas fault near Parkfield and extending to the Pacific coast near San Luis Obispo shed light on the rate of fault slip at depth since the 1966 earthquake. In this study, average rates of line length change and shallow fault slip were inverted to determine the slip rate at depth on the Parkfield fault segment. The fault is taken to be a vertical surface with unknown distribution of strike-slip displacement in an elastic half-space. A striking result of the inversions is that all solutions providing acceptable fits to the data exhibit a locked zone essentially coincident with the rupture surface of the 1966 Parkfield earthquake. The data require that the locked zone extend nearly as far north as the 1966 epicenter; however, the vertical extent of the locked zone is not well resolved. Over much of the Parkfield segment the fault is slipping faster at the earth's surface than it is at seismogenic depths. In order to fit the trilateration measurements it is necessary to include a component of contraction normal to the trend of the San Andreas. The inversion results suggest a spatially uniform normal strain of −0.06 μstrain/yr. The orientation of the contraction is compatible with geologic and seismic evidence of active folding and reverse faulting in the region. The magnitude of the contraction is consistent with convergence rates inferred from global plate motion models.

Journal of Geophysical Research Solid Earth↗
USGS2007

A cold phase of the East Pacific triggers new phytoplankton blooms in San Francisco Bay

Ecological observations sustained over decades often reveal abrupt changes in biological communities that signal altered ecosystem states. We report a large shift in the biological communities of San Francisco Bay, first detected as increasing phytoplankton biomass and occurrences of new seasonal blooms that began in 1999. This phytoplankton increase is paradoxical because it occurred in an era of decreasing wastewater nutrient inputs and reduced nitrogen and phosphorus concentrations, contrary to the guiding paradigm that algal biomass in estuaries increases in proportion to nutrient inputs from their watersheds. Coincidental changes included sharp declines in the abundance of bivalve mollusks, the key phytoplankton consumers in this estuary, and record high abundances of several bivalve predators: Bay shrimp, English sole, and Dungeness crab. The phytoplankton increase is consistent with a trophic cascade resulting from heightened predation on bivalves and suppression of their filtration control on phytoplankton growth. These community changes in San Francisco Bay across three trophic levels followed a state change in the California Current System characterized by increased upwelling intensity, amplified primary production, and strengthened southerly flows. These diagnostic features of the East Pacific "cold phase" lead to strong recruitment and immigration of juvenile flatfish and crustaceans into estuaries where they feed and develop. This study, built from three decades of observation, reveals a previously unrecognized mechanism of ocean-estuary connectivity. Interdecadal oceanic regime changes can propagate into estuaries, altering their community structure and efficiency of transforming land-derived nutrients into algal biomass.

California↗
USGS2008

Recent shallow marine ostracods from high latitudes: Implications for late Pliocene and Quarternary palaeoclimatology

New information about modern high-latitude marine ostracod faunas and about their occurrence in late Pliocene and Quaternary sequences promotes the application of these microfossils to palaeoenvironmental, palaeo-biogeographical and palaeoclimatological problems. Five poorly known species ( Cluthia cluthae, Finmarchinella logani, Roundstonia globulifera, Roundstonia macchesneyi and Semicytherura complanata ) from North Atlantic, North Pacific and Arctic areas are confirmed as extant and are used to demonstrate the potential of marine ostracods as tools for palaeoclimate studies. The genus Bonnyannella Athersuch, 1982 is shown to be a junior synonym of Roundstonia Neale, 1973.

Boreas↗
USGS2010

Turbidity on the shallow reef off Kaulana and Hakioawa watersheds, north coast of Kaho'olawe, Hawai'i: Measurements of turbidity and ancillary data on winds, waves, precipitation, and stream flow discharge, November 2005 to June 2008

The island of Kaho`olawe has particular cultural and religious significance for native Hawaiians. Once known as Kanaloa, the island was a center for native Hawaiian navigation. In the mid-20th century, the island was used as a bombing range by the U.S. Navy, and that practice, along with the foraging by feral goats, led to a near-complete decimation of vegetation. The loss of ground cover led to greatly increased erosion and run-off of sediment-laden water onto the island's adjacent coral reefs. Litigation in 1990 ended the U.S. Navy's use of the island as a bombing range, and in 1994 the island was transferred to the Kaho`olawe Island Reserve Commission (KIRC), http://kahoolawe.hawaii.gov/. As a result of the litigation, the U.S. Navy began a 10-year clean-up effort that was the foundation for the present restoration effort by KIRC (Slay, 2009). The restoration effort is centered on revegetating the island, reducing erosion, and limiting run-off onto adjacent reefs. Restoration efforts to mitigate sediment runoff to streams and gulches by restoring native vegetation and minimizing erosion have focused on two watersheds, Kaulana and Hakioawa, on the northeast and northwest sides of the island, respectively. Stream flow and sediment gages were installed by the U.S. Geological Survey Pacific Islands Water Science Center in each of the watersheds, and a weather station was established upland of the watersheds. For this study, turbidity monitors were installed on the insular shelf off the two watersheds to monitor the overall quality of reef waters and their changes in response to rain and stream flow discharge events.

Hawaii↗
USGS2022

Passage of adult coho salmon (Oncorhynchus kisutch) over Lake Creek Falls, Oregon, 2019

Across the Pacific Northwest, there are many examples of artificial structures created to allow passage of upstream-migrating salmon over natural barriers. We studied upstream passage across three structures installed in 1989 to allow passage of salmon over Lake Creek Falls, a series of three natural waterfalls at the outlet of Triangle Lake on Lake Creek, in the central Oregon Coast Range (lat 123.57508°; long 44.15735°). To track upstream passage by adult coho salmon ( Oncorhynchus kisutch ), 87 fish were tagged using gastrically implanted radio tags. Tracking was accomplished with a series of stationary receivers installed to detect crossings at each of three structures—over Lake Creek Falls using two upstream Denil-type ladders and a bypass downstream constructed to mimic a natural side channel. Tracking spanned the upstream migration and spawn timing for adult coho salmon in the basin and extended from October 2019 to February 2020. A total of 15 coho salmon (17 percent) were tagged in October, 30 coho salmon (35 percent) were tagged in November, and 42 coho salmon (48 percent) were tagged in December. Later-than-normal precipitation and associated low discharge delayed upstream migrations. Accordingly, most fish arrived late in the season (late November and December) and in sudden flushes with the erratic rain events. Fish that were tagged earlier were more likely to cross all three ladders, with more than 93 percent of fish tagged in October compared to 46.7 and 19.0 percent of November and December fish passing, respectively. The decline in passage rate could be attributed to the overlapping influences of stream discharge and advanced stage of maturation (lower energy reserves) of fish later in the season. Near the end of the study, both fish that crossed and fish obstructed by barriers were observed in tributaries known to be used for spawning by coho salmon. Without a much longer-term study involving many more fish than the current study, more intensive tracking, and coverage of different flow years, firm conclusions are difficult to draw regarding the overall influences of the passage structures on the likelihood of upstream passage by adult coho salmon. However, substantial numbers of fish are capable of crossing during certain conditions. The population-level consequences of the barriers on spawning distribution and the production of coho salmon in the watershed are not clear. Additional empirical study or population modeling could be used to address this question in more detail.

Oregon↗
USGS2025

Northward migrations of nonbreeding Bald Eagles from Arizona, USA.

Knowledge of the spatiotemporal patterns of migratory and nonbreeding-season movements by animals is critical for conservation, but can be difficult to obtain if animals move far from known breeding territories and across administrative and country borders. To understand the migratory movements of Bald Eagles ( Haliaeetus leucocephalus ) originating from a demographically closed population in Arizona, USA, we deployed GPS transmitters on 24 juveniles and 2 nonbreeding adult eagles between 2017 and 2023. We identified common migration routes, stopover locations, and migration phenology. Eagles moved north from Arizona during the population's post-breeding period in the boreal spring and summer, and returned south in autumn in advance of the breeding season. Eagles migrated along two primary routes: (1) along the Wasatch Mountains in Utah and extending into the Rocky Mountains of southern Idaho, and (2) through eastern Nevada and along the Rocky Mountains in western and northern Idaho. Stopover locations were frequently near lakes and rivers. Recent fledglings began migration later than older individuals and 15 of 16 of these juveniles that survived until the following breeding season returned to Arizona. The individual that did not return showed evidence of permanent emigration to northern California. Our results contribute to a growing understanding of avian migration routes within the Pacific Flyway and the diverse migration strategies, including northward migration following the breeding season, exhibited across raptor populations. We highlight that explicit studies of juveniles, subadults, and nonbreeding adults are key to understanding avian migration dynamics and identifying opportunities for conservation.

Arizona↗
USGS2005

Resource inventory of marine and estuarine fishes of the West Coast and Alaska: A checklist of North Pacific and Arctic Ocean species from Baja California to the Alaska - Yukon border

This is a comprehensive inventory of the fish species recorded in marine and estuarine waters between the Alaska–Yukon Territory border in the Beaufort Sea and Cabo San Lucas at the southern end of Baja California and out about 300 miles from shore. Our westernmost range includes the eastern Bering Sea and Aleutian Islands. In addition, we have also included our best impressions of the species that might reasonably be expected to be members of the West Coast ichthyofauna but have not yet been captured or reported within our study area. These species are marked with an asterisk (*) and have been reported (1) in the western Bering Sea; (2) off Canada’s Yukon Territory and adjacent portions of the Northwest Territories; (3) along the southern-eastern tip (non-Pacific side) of Baja California; and (4) in waters somewhat beyond 300 miles from shore. Although the term West Coast usually refers to the coast of the continuous western states, our usage herein means the entire study area. The West Coast inventory within this range encompasses fish fauna from 44 orders, 232 families, and a minimum of 1,450 species. Please note that introduced and invasive fish species are marked by double asterisks (**) and that their scientific names are highlighted in gray. We have compiled this document because the most geographically inclusive previous inventories (Jordan and Evermann 1896a, Jordan et al. 1930) are largely of historical interest and are out of date. More recent lists and compilations have either focused on relatively narrow taxonomic groups (e. g., Kramer et al. 1995, Love et al. 2002), are regional in scope (e. g., Hart 1973, Hubbs et al. 1979, Mecklenburg et al. 2002), or focus on commonly observed species (e. g., Miller and Lea 1972, Eschmeyer and Herald 1983). With the explosion of coastal research and environmental assessments, beginning in the 1970s, and more recently, renewed scientific interest in biodiversity (e.g., effects of global climate change), our own studies on related subjects regarding fish populations, assemblages, and biological habitats, suggested this was the appropriate time to update and summarize our knowledge.

Report↗
USGS2024

Cycles in adult steelhead length suggest interspecific competition in the North Pacific Ocean

Anadromous fishes rely on abundant prey in the ocean to grow large quickly, but prey limitation leads to interspecific competition. When species interactions are difficult to observe, growth can be studied to detect otherwise cryptic signals of competition. We describe a previously undocumented two-year cycle in the lengths of adult natural-origin steelhead ( Oncorhynchus mykiss ) returning to spawn in the Snake River Basin. Returning steelhead were 38 mm shorter on odd return years, not accounting for sex, stock, and years of ocean residence. The well-known cycle in abundance of Pink Salmon from eastern Kamchatka and North America had statistically significant negative effects on returning steelhead lengths that depended on sex and the number of years of ocean residence. These results suggest that competition for limited resources occurs well after initial ocean entry and that interactions during later stages of ocean residence can be influential. Interspecific competition has implications for future returns of steelhead from the ocean, especially as metabolic demands for steelhead increase as the ocean warms.

North Pacific Ocean↗