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At least 1,171 records · Page 65Linked to original sources
USGS1979

Artificial transmission to and susceptibility of Puget Sound fish to viral erythrocytic necrosis (VEN)

In Puget Sound, Wash., the incidence of viral erythrocytic necrosis (VEN) varied geographically from 0 to 17% in chum salmon ( Oncorhynchus keta ) and from 4 to 59% in Pacific herring ( Clupea harengus pallasi ). The disease was experimentally transmitted by intraperitoneal injection to chum, pink ( O . gorbuscha ), coho ( O . kisutch ), chinook ( O . tshawytscha ), sockeye ( O . nerka ), and Atlantic ( Salmo salar ) salmon, and rainbow ( S . gairdneri ), brown ( S . trutta ), and brook ( Salvelinus fontinalis ) trout. The disease was transmitted to chum salmon and brook trout by waterborne virus. Virus obtained from herring was experimentally transmitted into chum salmon by intraperitoneal injection. Key words : viral erythrocytic necrosis, fish disease, transmission

Washington↗
USGS1996

Predation by sea lamprey (Petromyzon marinus) on lake trout (Salvelinus namaycush) in southern Lake Ontario, 1982-1992

Dead lake trout ( Salvelinus namaycush ) killed by sea lamprey (P etromyzon marinus ) were collected from the bottom of Lake Ontario using bottom trawls. The number of dead lake trout per hectare could be predicted from the number of type A-1 sea lamprey marks observed on live fish in September gillnet surveys ( r 2 = 0.60, P < 0.01) but not from the sum of marks of types A-1, A-2, and A-3 combined. Sea lamprey selectively attacked and killed the largest lake trout. The lengths and ages of live fish with A-1 marks increased as the population of longer, older lake trout in the lake increased, and the length distributions of fish killed by sea lamprey were not different ( P > 0.05) from those of live fish with A-1 marks in 5 of 6 years where comparisons could be made. Compared with Lake Superior strain lake trout, Seneca Lake strain fish were only 0.41 times as likely to be attacked by sea lamprey and were less likely to die from an attack (both differences P < 0.05). Conservative estimates of the numbers of lake trout killed by sea lamprey in southern Lake Ontario from October to mid-November ranged from 17,000 in 1988 to 121,000 in 1984.

New York, Ontario↗
USGS1997

Characterization and application of a quantitative DNA marker that discriminates sex in Chinook salmon ( Oncorhynchus tshawytscha )

A qualitative male-specific DNA marker (OT-24) was amplified by spPCR (single-primer polymerase chain reaction) from chinook salmon (Oncorhynchus tshawytscha) DNA along with several non-sex-linked products. The termini of the male-specific product were sequenced, and a pair of PeR primers were constructed for marker-specific PCR amplification. Dual primer PCR (dpPCR), with the marker-specific primers, amplified a product from both nudes and females. The amount of dpPCR product amplified from males was at least 100-fold greater than that from females. The quantitative difference between males and females was consistent among geographically distinct populations from western U.S. rivers. In addition, DNA sequence analysis indicated that OT-24 was highly conserved among geographically distinct salmon populations. The qualitative spPCR product segregated through several genetic crosses indicating equal sex ratios among progeny. Identification of the male and female juveniles by dpPCR was consistent with the spPCR analysis. There was no tissue specificity observed by spPCR or dpPCR analysis of this marker. A rapid DNA extraction method and dpPCR analysis were used to nonlethally determine sex ratios in wild spring chinook salmon adults, withheld for genetic and behavioral studies, prior to their development of gross sexual differences in their external morphology.

Canadian Journal of Fisheries and Aquatic Sciences↗
USGS2003

Shallow landsliding, root reinforcement, and the spatial distribution of trees in the Oregon Coast Range

The influence of root reinforcement on shallow landsliding has been well established through mechanistic and empirical studies, yet few studies have examined how local vegetative patterns influence slope stability. Because root networks spread outward from trees, the species, size, and spacing of trees should influence the spatial distribution of root strength. We documented the distribution and characteristics of trees adjacent to 32 shallow landslides that occurred during 1996 in the Oregon Coast Range. Although broadly classified as a conifer-dominated forest, we observed sparse coniferous and abundant hardwood trees near landslide scars in an industrial forest (Mapleton) that experienced widespread burning in the 19th century. In industrial forests that were burned, selectively harvested, and not replanted (Elliott State Forest), swordfern was ubiquitous near landslides, and we observed similar numbers of live conifer and hardwood trees proximal to landslide scarps. We demonstrate that root strength quantified in landslide scarps and soil pits correlates with a geometry-based index of root network contribution derived from mapping the size, species, condition, and spacing of local trees, indicating that root strength can be predicted by mapping the distribution and characteristics of trees on potentially unstable slopes. In our study sites, landslides tend to occur in areas of reduced root strength, suggesting that to make site-specific predictions of landslide occurrence slope stability analyses must account for the diversity and distribution of vegetation in potentially unstable terrain.

Oregon↗
USGS1986

In situ and laboratory geotechnical tests of the Pierre Shale near Hayes, South Dakota — A characterization of engineering behavior

A geotechnical investigation of the Pierre Shale near Hayes, South Dakota, was conducted by the U.S. Geological Survey as a basis for evaluating problems in deep excavations into that formation. The physical and mechanical properties of the shale were determined through use of core holes drilled to a maximum depth of 184 m. In situ borehole determinations included a gravimeter survey, pressuremeter testing, thermal profile measurements, and borehole velocity measurements. Onsite and offsite laboratory measurements included rebound measurements, sonic velocity measurements of shear and primary waves, X-ray mineralogy and major element determinations, size analyses, fracture analyses, fabric analyses, and determination of thermal properties.Below 15–22 m, the shale is an unweathered, saturated, overconsolidated, underpressured clay shale with a clay-mineral content ranging between 50 and 100%, dominantly composed of mixed-layer illitic smectites. The physical and mechanical properties vary widely. The variation is related to the clay mineral content (especially in bentonite zones), a large transverse mechanical anisotropy, and zones of fractures and microfractures, which may result from rebound caused by erosion. These may contribute to slope instability over large areas. The thermal and mechanical properties change markedly if the shale is permitted to dry out. The state of stress and overconsolidation appear to be functions of the depositional and erosional history of the deposit. Both are markedly affected by the large fracture zones. The properties of the clay shale indicate problems that may be encountered in excavation and use of deep underground facilities. Key words : anisotropy, characterization, clay shale, consolidation state, physical properties, rebound, relaxation, stress state, thermal properties.

South Dakota↗
USGS1996

Den use by arctic foxes ( Alopex lagopus ) in a subarctic region of western Alaska

Distribution, abundance, and use of arctic fox dens located in coastal tundra communities of the Yukon–Kuskokwim delta were determined in studies from 1985 to 1990. Dens were denser and less complex than those described in studies conducted above the Arctic Circle. Eighty-three dens of varying complexity were found in the 52-km 2 study area. Nineteen dens were used by arctic foxes for whelping or rearing pups. Three females relocated litters to multiple dens; a maximum of four dens were used concurrently by pups from one litter. Although red foxes ( Vulpes vulpes ) were common in the region, their use of dens in the study area was minimal. Differences in vegetation at den sites and nearby unoccupied sites were minimal. Furthermore, den sites could not be distinguished from non-den sites during aerial surveys.

Alaska↗
USGS2022

The tectonic significance of pre-Scandian 40Ar/39Ar phengite cooling ages in the Caledonides of western Norway

Pre-Silurian continental-margin deposits in western Norway, non-conformably overlying allochthonous continental orthogneisses retain Ordovician 40 Ar/ 39 Ar cooling ages for phengites, implying either rapid cooling immediately after a Late Ordovician orogenic event, or less likely, a slow cooling following an Early Ordovician or older orogeny. The Dalsfjord Suite–Høyvik Group basement–cover pair are probably a lateral equivalent to Late Proterozoic sandstones (‘sparagmites’) covering the Jotun Nappe gneisses of the Middle Allochthon in central-south Norway. The Høyvik Group underwent polyphase deformation, greenschist-facies metamorphism ( T max <450°C) and exhumation prior to deposition of the unconformably overlying Wenlockian continental-margin deposits of the Herland Group. The Høyvik Group was only weakly metamorphosed during obduction of the Solund–Stavfjord Ophiolite and the Scandian continental collision between Baltica and Laurentia. Phengitic white micas from the Høyvik Group yield cooling ages of 446.1± 3.0, 449.1±2.2 and 447.5±4.0 Ma, respectively, identical within experimental error. One sample gives a plateau over 72% of the gas analysed, whereas the other samples were slightly disturbed after initial cooling, as indicated by systematically lower apparent ages at low experimental extraction temperatures. Minor 40 Ar loss probably occurred during subsequent Scandian deformation and late to post-orogenic extension.The Høyvik Group rocks were unroofed before the Wenlock time (423–428 Ma) and cooled through the temperature for argon retention in phengite at c . 447±4 Ma, indicating a maximum cooling rate between 14 and 22C/Ma- 1 through Ashgill and Llandovery times before being subjected to low-grade metamorphism during the Scandian orogeny. Rapid pre-Scandian cooling, combined with peak metamorphic conditions of 450C or less, may indicate that the Dalsfjord–Høyvik basement–cover pair were aVected by an orogenic event during the Late Ordovician (Caradoc) time. The data also suggest that the Caledonian margin of Baltica may have experienced a more protracted tectonism during the Caledonian cycle than previously models focusing on Early Caledonian and Tremadoc (or older) ophiolite obduction and the Scandian continental collision between Baltica and Laurentia.

Journal of the Geological Society↗
USGS2022

Debris flows originating from soil slips during rainstorms in Southern California

Debris flows generated during rainstorms present a greater risk of death and injury to southern California residents than all other kinds of slope failure combined. During the years 1962-1971, twenty-three people in the greater Los Angeles area died from being buried or struck by debris flows, all of which probably originated as soil slips. Soil slips and debris flows are recurring major natural geomorphological processes in the region. Soil slips are reconstituted into debris flows when the initial movement (sliding failure) of slabs of soil and wedges of ravine fill causes remoulding of the saturated moving mass into viscous, debris-laden mud, which then flows down available drainage courses. This change of state results in a marked reduction in resistance to shear, permitting masses to accelerate down the same slopes on which, only moments earlier, the slabs of soil mantle had barely overcome the resistance to sliding. Many flows reach avalanche speeds and do not begin to deposit significant amounts of detritus until they reach lower gradients far from their sources. The deposits form steep ‘alluvial’ fans at the mouths of short, steep drainage basins tributary to broad valleys, and form debris trains in and along narrow trunk canyons below the mouths of short, steep tributaries. The exceptional storm period of January 18th to 26th, 1969, was accompanied by thousands of soil slips and provided an unusual opportunity to determine the times of occurrence of numerous debris flows, establish their origin from soil slips, and compare the times of those events with rainfall records from an extensive network of continuously recording rain gauges and a sequential set of radar weather maps. An empirical association between soil slips and rainfall suggests that a 10 inch antecedent rainfall is required to bring most of the colluvial soil of the area to field capacity, and 0.25 inch-per-hour is the minimum rate at which surface infiltration exceeds subsoil drainage for most of the colluvial soils of the area so that pore pressures are raised in a zone above the less permeable parent materials. Soil moisture of this level also appears to be sufficient so that most of the colluvial soils of the area will become at least partly liquid when disturbed. GeoRef Subject

California↗
USGS2022

Spring mudflows at Wrightwood, Southern California

The Wrightwood area in the San Gabriel Mountains of southern California is known as a site of recurring mudflow activity. The community of Wrightwood is built on the coalesced fans of Sheep, Acorn and Heath Creeks, and the fan deposits are probably chiefly of mudflow origin. Historically, mudflows there have been observed in association with three climatic conditions: (1) short period of high-intensity rainfall during the summer dry season (thunderstorms); (2) periods of heavy rainfall during the October-March winter season, when most of the year's rain and snow fall; and (3) thaw of the winter snow pack. The mudflow activity associated with heavy rainfall has generally been of only a few hours or at most a few days duration. Mudflow activity associated with spring thaw has been of longer duration, as much as several weeks. At various times in the past, mudflows generated by all three conditions have inundated homes and highways in the Wrightwood area, which is now defended by a flood control levee system. During May and June, 1969 the rapid melting of a heavy snow pack resulted in a 40-day period of mudflow activity in Heath Creek. All flows originated in the steep upper reaches of Heath Creek, where steep ravines are incised in the toe of a large active landslide. Direct observation by the authors showed that flows formed when small masses of debris fell or slid from the surface of the landslide mass into the steep channel. Some of the masses were fluid enough to continue downstream without interruption; others stopped in the channel until remobilized by added melt water or the passage of a mudflow from a higher altitude. Both processes resulted in discrete ‘slugs’ which continued down the steep ravine, through an allu-viated canyon, to a fan where most of the debris was deposited. The activity may be described as a spring mudflow cycle, within which three stages were observed in a gradational sequence. A waxing stage began with sporadic short-duration mudflows, during which the lower alluviated canyon floor of Heath Creek was aggraded. A climactic stage of larger mudflows at more frequent intervals and of longer duration was characterized by the incision of a single, narrow, U-shaped channel in the alluviated canyon floor, and transportation of debris as much as 2 miles (3.2 km) from the source. A waning stage followed as meltwater supply decreased; short-duration flows backfilled the U-shaped channel and spilled over the banks, again aggrading the alluviated canyon floor.

California↗
USGS2008

Buruli ulcer disease prevalence in Benin, West Africa: Associations with land use/cover and the identification of disease clusters

Background: Buruli ulcer (BU) disease, caused by infection with the environmental mycobacterium M. ulcerans, is an emerging infectious disease in many tropical and sub-tropical countries. Although vectors and modes of transmission remain unknown, it is hypothesized that the transmission of BU disease is associated with human activities in or around aquatic environments, and that characteristics of the landscape (e.g., land use/cover) play a role in mediating BU disease. Several studies performed at relatively small spatial scales (e.g., within a single village or region of a country) support these hypotheses; however, if BU disease is associated with land use/cover characteristics, either through spatial constraints on vector-host dynamics or by mediating human activities, then large-scale (i.e., country-wide) associations should also emerge. The objectives of this study were to (1) investigate associations between BU disease prevalence in villages in Benin, West Africa and surrounding land use/cover patterns and other map-based characteristics, and (2) identify areas with greater and lower than expected prevalence rates (i.e., disease clusters) to assist with the development of prevention and control programs. Results: Our landscape-based models identified low elevation, rural villages surrounded by forest land cover, and located in drainage basins with variable wetness patterns as being associated with higher BU disease prevalence rates. We also identified five spatial disease clusters. Three of the five clusters contained villages with greater than expected prevalence rates and two clusters contained villages with lower than expected prevalence rates. Those villages with greater than expected BU disease prevalence rates spanned a fairly narrow region of south-central Benin. Conclusion: Our analyses suggest that interactions between natural land cover and human alterations to the landscape likely play a role in the dynamics of BU disease. For example, urbanization, potentially by providing access to protected water sources, may reduce the likelihood of becoming infected with BU disease. Villages located at low elevations may have higher BU disease prevalence rates due to their close spatial proximity to high risk environments. In addition, forest land cover and drainage basins with variable wetness patterns may be important for providing suitable growth conditions for M. ulcerans, influencing the distribution and abundance of vectors, or mediating vector-human interactions. The identification of disease clusters in this study provides direction for future research aimed at better understanding these and other environmental and social determinants involved in BU disease outbreaks. ?? 2008 Wagner et al; licensee BioMed Central Ltd.

International Journal of Health Geographics↗
USGS1986

Changes in growth and maturity of walleyes associated with stock rehabilitation in western Lake Erie, 1964-1983

The precipitous decline in abundance of walleyes (Stizostedion vitreum vitreum) in western Lake Erie during the 1960s caused major concerns for the future of this resource. Mercury contamination in walleyes in 1970 resulted in a moratorium on commercial fishing in United States and Canadian waters. The opportunity arose for resource agencies to develop a plan for rehabilitation of the walleye stocks, and quota management for walleyes was begun in 1976. After 8 years, the resource had recovered dramatically and the estimated standing stock in 1983 was more than three times that in 1976. In the mid-1970s, however, certain detrimental changes suggested that self-regulatory mechanisms were occurring. The growth rate declined gradually but rather consistently. Growth changes were most evident for young-of-the-year (YOY), yearlings, and 2-year-old fish, which usually constituted more than 80% of the standing stock in 1976-1983. Average lengths of YOY fish decreased by nearly 50 mm (from about 240 mm in 1961 to 190 mm in 1983). Average lengths and weights of yearling and older fish began to decline after 1975 and decreased markedly after 1980. Historically, growth of walleyes in western Lake Erie exceeded that reported for many walleye populations in other waters. Another sign of self-regulation was an increasing delay in the onset of maturity. Most (usually more than 90%) of the yearling males were sexually mature each fall before 1979, but this percentage decreased to only 32 by fall 1983. Usually 80% or more of the age-II females were mature each fall during the 1960s and early 1970s, but this percentage decreased rapidly to only 7 by fall 1983. Prey fish populations declined somewhat in the early 1980s, and their ability to sustain the high abundance of walleyes is a great concern to resource managers.

North American Journal of Fisheries Management↗
USGS1991

Infectious hematopoietic necrosis (IHN) and viral hemorrhagic septicemia (VHS): Detection of the trout antibodies to the causative viruses by means of plaque neutralization, immunofluorescence, and enzyme-linked immunosorbent assay

Sera collected from cultured rainbow trout Oncorhynchus mykiss surviving outbreaks of infectious hematopoietic necrosis (IHN) or viral hemorrhagic septicemia (VHS) were examined for the presence of antibodies to both of the causative viruses, infectious hematopoietic necrosis virus (IHNV) and Egtved virus (viral hemorrhagic septicemia virus: VHSV). Sera were screened with three serological tests: 50% plaque neutralization test (PNT), immunofluorescence (IF), and enzyme-linked immunosorbent assay (ELISA). In sera from 20 rainbow trout surviving IHN, antibodies to IHNV were detected in 9 fish by PNT, in 12 fish by IF, and in 9 fish by ELISA. In these sera, antibodies cross-reacting with VHSV were rare (detected in 0 fish by PNT, in 1 by IF, and in 1 by ELISA). In sera from 20 rainbow trout surviving VHS, antibodies to VHSV were detected in 9 fish by PNT, in 16 fish by IF, and in 18 fish by ELISA. A considerable percentage of the VHS-survivor sera contained antibodies that cross-reacted with IHNV, as detected by ELISA (16 fish) and 1F (7 fish) but not by PNT (0 fish). The three serological tests appear to be useful tools for IHNV and VHSV epidemiology; however, the presence of cross-reacting antibodies in some sera suggests caution when farms require specific pathogen-free certification for one of the viruses in the presence of the other.

Journal of Aquatic Animal Health↗
USGS1997

Virulence of Renibacterium salmoninarum to salmonids

Virulence of Renibacterium salmoninarum isolates representing five origins was evaluated in eight salmonid hosts; four origins were of Lake Michigan and the fifth was of the Pacific Northwest. The species type strain, ATCC (American Type Culture Collection) 33209, was also included. Each isolate was grown in a kidney disease medium (KDM2) supplemented with 1 % ATCC 33209 culture metabolite; serial 10-fold dilutions were prepared, and groups of fish were challenged by intraperitoneal injection with 0.1 mL of each dilution. A 70-d observation period followed, and bacterial kidney disease (BKD) was diagnosed by the fluorescent antibody technique. Virulence of isolates was quantified as a dose lethal to 50% of fish (LD50) for each host&ndash;isolate challenge. In the first set of experiments, 23 isolates were used to challenge groups of brook trout Salvelinus fontinalis. The mean LD50 was 1.087 x 10 6 colony-forming units per milliliter (cfu/mL; SD = 2.022 x 10 6 ), and the LD50 values ranged from 8.457 x 10 6 to 2.227 x 10 4 cfu/mL. Analysis of variance to evaluate the effect of isolate origin on virulence in brook trout revealed no significant difference ( F = 1.502; P = 0.243). Susceptibilities of the other salmonid hosts were evaluated by challenge with six isolates of R. salmoninarum representing each origin and the species type strain. For many of the host&ndash;isolate challenge combinations, time to death was highly dependent on the dilution (number of bacteria) injected. In general, the isolates MCO4M, B26, and A34 (all of Lake Michigan origin) tended to be more virulent. Also, LD50 values were dispersed throughout a wider range among the more susceptible hosts. Lake trout Salvelinus namaycush, rainbow trout Oncorhynchus mykiss, and brook trout were relatively resistant to challenge with the strains, whereas coho salmon O. kisutch, domestic Atlantic salmon Saltno salar, and chinook salmon O. tshawytscha were relatively susceptible. Another challenge evaluated the effect of washing R. salmoninarum MCO4M cells before injection into brook trout. The calculated LD50 value, 2.009 x 10 5 cfu/mL, was similar ( X 2 = 0.878; P = 0.645) to that of the unwashed cells (1.163 x 10 5 cfu/mL). Furthermore, times to death for successive dilutions were similar regardless of whether or not the cells were washed.

Journal of Aquatic Animal Health↗
USGS1992

Evaluating enhancement of striped bass in the context of potential predation on anadromous salmonids in Coos Bay, Oregon

We describe an approach for evaluating the predation on anadromous salmonids that could result from enhancement of striped bass Morone saxatilis in Coos Bay, Oregon. Predation by striped bass on juvenile salmonids has been documented there since 1930. To provide a basis for the decision about enhancement of striped bass in Coos Bay, we estimated the losses of anadromous salmonids in 1950 and 1960–1964. In this evaluation, we used information on striped bass in Coos Bay and collateral information about striped bass in other waters. Estimated numbers of juvenile salmonids consumed by striped bass in Coos Bay (April–June) ranged from more than 41,000 in 1950 to about 383,000 in 1963. Estimated losses of adult salmonids ranged from about 1,000 in 1950 to about 46,000 in 1963. This approach was useful in conveying the potential consequences of large‐scale striped bass enhancement to decision makers and to the public. The evaluation also helped identify information needs that are now considered in managing the fishery and in evaluating impacts on salmonids.

Oregon↗
USGS1994

Evaluation of tire reefs for enhancing aquatic communities in concrete-lined canals

Large earthen canals in the arid southwest are being lined with concrete to reduce seepage and conserve limited water supplies. Lining reduces habitat and increases operational velocities (relative to unaltered streams), which are detrimental to aquatic communities. Fish communities that become reestablished in these waterways exhibit lower species diversity, densities, and biomass than they did in the former earthen canals. Placement of low-profile tire reefs in the Coachella Canal, California, and the Hayden-Rhodes Aqueduct, Arizona, reversed these trends. Comparative sampling revealed that invertebrate and fish densities were 3 and 20 times higher, respectively, in reef areas than in typical canal sections without reefs. Tire reefs are recommended as an effective means of enhancing aquatic communities in concrete canals.

North American Journal of Fisheries Management↗
USGS1995

Management briefs: Phototaxis of larval and juvenile northern pike

Age-0 northern pike Esox lucius prefer vegetated habitats that are difficult to sample with standard towed gears. Light traps can be effective for sampling larval fishes in dense vegetation, given positive phototaxis offish. We evaluated the phototactic response of young northern pike by comparing the catches of larvae and juveniles obtained with plexiglass traps deployed with a chemical light stick versus traps deployed without a light source (controls) in a laboratory raceway and in a vegetated pond. In the laboratory tests, catches of protolarvae and mesolarvae in lighted traps were 11–35 times greater than catches in control traps. The catches of juvenile northern pike in field and laboratory experiments were 3–15 times greater in lighted traps than in control traps, even though the maximum body width of the larger juveniles was similar to the width of the entrance slots of the traps (5 mm). Larval and juvenile northern pike were photopositive; thus, light traps should effectively sample age-0 northern pike for at least 6 weeks after hatching.

Wisconsin↗
USGS2000

Seasonal changes in ruffe abundance in two Lake Superior tributaries: Implications for control

Since the discovery of ruffe Gymnocephalus cernuus in the St. Louis River in 1987, state, federal, and tribal management agencies have sought to slow its spread to areas outside the western end of Lake Superior. A debate over control strategies highlighted uncertainties about seasonal movements of this species between Lake Superior and its western tributaries. One strategy called for eliminating reproducing populations in tributaries on the periphery of the range using chemical piscicides. That strategy rested on the assumption that ruffe congregate in tributaries during a predictable time of year. This study was designed to explore that assumption. Ruffe collections from the Iron and Sand rivers during 1995 indicated that ruffe were present in those tributaries throughout the summer but that abundance was not highest at the predicted time: June 19&ndash;22. Maximum abundance in the Iron River did not coincide with that in the Sand River and did not occur during June 19&ndash;22 in either river. The timing of peak abundance was not clearly related to changes in water temperature. Ruffe were present in substantial numbers in Lake Superior during June 19&ndash;22 when aggregations in the tributaries had been predicted. These findings do not support the assumption of the chemical control strategy.

North American Journal of Fisheries Management↗