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At least 541 records · Page 30Linked to original sources
USGS2018

Effects of the proposed California WaterFix North Delta Diversion on flow reversals and entrainment of juvenile Chinook salmon (Oncorhynchus tshawytscha) into Georgiana Slough and the Delta Cross Channel, northern California

The California Department of Water Resources and Bureau of Reclamation propose new water intake facilities on the Sacramento River in northern California that would convey some of the water for export to areas south of the Sacramento-San Joaquin River Delta (hereinafter referred to as the Delta) through tunnels rather than through the Delta. The collection of water intakes, tunnels, pumping facilities, associated structures, and proposed operations are collectively referred to as California WaterFix. The water intake facilities, hereinafter referred to as the North Delta Diversion (NDD), are proposed to be located on the Sacramento River downstream of the city of Sacramento and upstream of the first major river junction where Sutter Slough branches from the Sacramento River. The NDD can divert a maximum discharge of 9,000 cubic feet per second (ft 3 /s) from the Sacramento River, which reduces the amount of Sacramento River inflow into the Delta. In this report, we conducted three analyses to investigate the effect of the NDD and its proposed operation on entrainment of juvenile Chinook salmon ( Oncorhynchus tshawytscha ) into Georgiana Slough and the Delta Cross Channel (DCC). Fish that enter the interior Delta (the network of channels to the south of the Sacramento River) through Georgiana Slough and the DCC survive at lower rates than fish that use other migration routes (Sacramento River, Sutter Slough, and Steamboat Slough). Therefore, fisheries managers were concerned about the extent to which operation of the NDD would increase the proportion of the population entering the interior Delta, which, all else being equal, would lower overall survival through the Delta by increasing the fraction of the population subject to lower survival rates. Operation of the NDD would reduce flow in the Sacramento River, which has the potential to increase the magnitude and duration of reverse flows of the Sacramento River downstream of Georgiana Slough. In the first analysis, we evaluate the effect of the NDD bypass rules on flow reversals of the Sacramento River downstream of Georgiana Slough. The NDD bypass rules are a set of operational criteria designed to minimize upstream transport of fish into Georgiana Slough and the DCC, and were developed based on previous studies showing that the magnitude and duration of flow reversals increase the proportion of fish entering Georgiana Slough and the DCC. We estimated the frequency and duration of reverse-flow conditions of the Sacramento River downstream of Georgiana Slough under each of the prescribed minimum bypass flows described in the NDD bypass rules. To accommodate adaptive levels of protection during different times of year when juvenile salmon are migrating through the Delta, the NDD bypass rules prescribe a series of minimum allowable bypass flows that vary depending on (1) month of the year, and (2) progressively decreasing levels of protection following a pulse flow event. We determined that the NDD bypass rules increased the frequency and duration of reverse flows of the Sacramento River downstream of Georgiana Slough, with the magnitude of increase varying among scenarios. Constant low-level pumping, the most protective bypass rule that limits diversion to 10 percent of the maximum diversion and is implemented following a pulse-flow event, led to the smallest increase in frequency and duration of flow reversals. In contrast, we found that some scenarios led to sizeable increases in the fraction of the day with reverse flow. The conditions under which the proportion of the day with reverse flow can increase by greater than or equal to 10 percentage points between October and June, when juvenile salmon are present in the Delta, include October–November bypass rules and level-3 post-pulse operations during December–June. These conditions would be expected to increase the proportion of juvenile salmon entering the interior Delta through Georgiana Slough. In the second analysis, we assessed bias in Delta Simulation Model 2 (DSM2) flow predictions at the junction of the Sacramento River, DCC, and Georgiana Slough. Because DSM2 was being used to simulate California WaterFix operations, understanding the extent of bias relative to USGS streamgages was important since fish routing models were based on flow data at streamgages. We determined that river flow predicted by DSM2 was biased for Georgiana Slough and the Sacramento River. Therefore, for subsequent analysis, we bias-corrected the DSM2 flow predictions using measured stream flows as predictor variables. In the third analysis, we evaluated the effect of the NDD on the daily probability of fish entering Georgiana Slough and the DCC. We applied an existing model to predict entrainment from 15-minute flow simulations for an 82-year time series of flows simulated by DSM2 under the Proposed Action (PA), where the North Delta Diversion is implemented under California WaterFix, and the No Action Alternative (NAA), where the diversion is not implemented. To estimate the daily fraction of fish entering each river channel, entrainment probabilities were averaged over each day. To evaluate the two scenarios, we then compared mean annual entrainment probabilities by month, water year classification, and three different assumed run timings. Overall, the probability of remaining in the Sacramento River was lower under the PA scenario, but the magnitude of the difference was small ( 3 /s. At flows greater than 41,000 ft 3 /s, we hypothesize that entrainment into the interior Delta is relatively constant, which would have caused little difference between scenarios at higher flows.

California↗
USGS2025

Trophic assessment of potential competition between invasive cichlids and sport fish in Puerto Rico reservoirs

Objective Several species of New World cichlids have recently invaded reservoirs in Puerto Rico, potentially jeopardizing established recreationally important, albeit nonnative, sport fish populations. Interactions between invasive species and important sport fish must be understood so that they can be mitigated when feasible. This study compared monthly prey consumption between three invasive cichlids (Jaguar Guapote Parachromis managuensis and two species of Amphilophus ) and two principal sport fishes (Largemouth Bass Micropterus nigricans and Butterfly Peacock Bass Cichla ocellaris ) to understand potential for competitive interactions. Methods Stomach contents were evaluated quarterly using gastric lavage for sport fish and destructive sampling techniques for invasive species. Prey proportion by mass was calculated for each individual, and mean prey proportion by mass was calculated for each species by reservoir, month, and overall. Multivariate hypothesis testing using permutational multivariate analysis of variance and visualization of potential diet overlap were performed via analysis of variance and nonmetric multidimensional scaling (NMDS), respectively. Results Fish were the most common prey type, and Threadfin Shad Dorosoma petenense was the most prevalent prey species. Although there were significant differences in diets of invasive cichlids and sport fishes ( P < 0.01), there also was considerable overlap based on low percentages of variation in diets explained by species (3–19% < pseudo- R 2 ) and NMDS visualizations. Diets varied little across reservoirs and months (≤4% pseudo- R 2 ; high overlap in NMDS space). Conclusion These data indicate that the diet of Jaguar Guapote and Amphilophus spp. may overlap with that of sport fish populations in Puerto Rico. Jaguar Guapote relied on Threadfin Shad more than other species, with Amphilophus spp. relying more on detritus and noncrayfish invertebrates. Thus, if prey are limited, Jaguar Guapote may have a more direct effect via competition for prey. Finally, we report evidence of Largemouth Bass recruitment failure and local extirpations that support a hypothesis that invasive cichlids are having negative effects on at least Largemouth Bass, although the mechanism is unclear.

Puerto Rico↗
USGS2016

Cooperative Fish and Wildlife Research Units Program—2015 Year In Review

Summary The Cooperative Fish and Wildlife Research Unit (CRU) Program had its 80th anniversary in 2015. We did not have a party, but those of us who work directly for the Unit program on a daily basis celebrate the privilege we feel in being part of one of the greatest conservation institutions in history. Our mission is our hallmark: meeting the actionable science needs of our cooperators, providing them technical guidance and assistance in interpreting and applying new advances in science, and developing the future workforce through graduate education and mentoring. Our success in accomplishing our mission is due principally to the caliber of the scientists and students they recruit, and the tremendous support from our cooperators. The National Cooperators Coalition has been active in fostering support and I am very excited about their energy. A Special Session at the 2015 North American Wildlife and Natural Resources Conference was dedicated to the Unit program, and a vision for our future was presented at this most prestigious conservation policy forum. We compiled a directory of expertise within the Unit program organized within thematic science areas as identified by our cooperators. We intend for this directory to facilitate our transboundary initiatives where two or more Units in collaboration will be the catalyst that binds agencies and organizations together on landscape scale conservation science. We are co-sponsoring a workshop at the 2016 North American conference, along with the Association of Fish and Wildlife Agencies, the American Fisheries Society, and The Wildlife Society to jump-start a dialogue on and identify issues associated with the widening gap between science and management. The CRU is viewed by our cooperators as being the standard for delivering actionable science in conservation, and the exception to the emerging trend. This is testament to the legacy of the Unit Program and the foundation it is built upon. In this Year in Review report, you will find details on staffing, vacancies, research funding, and other pertinent information. You will also see snapshots of Unit projects with information on how results have been or are being applied by cooperators. That is the essence of what we do: science that matter.

Circular↗
USGS2014

Invasion of Asian tiger shrimp, Penaeus monodon Fabricius, 1798, in the western north Atlantic and Gulf of Mexico

After going unreported in the northwestern Atlantic Ocean for 18 years (1988 to 2006), the Asian tiger shrimp, Penaeus monodon , has recently reappeared in the South Atlantic Bight and, for the first time ever, in the Gulf of Mexico. Potential vectors and sources of this recent invader include: 1) discharged ballast water from its native range in Asia or other areas where it has become established; 2) transport of larvae from established non-native populations in the Caribbean or South America via ocean currents; or 3) escape and subsequent migration from active aquaculture facilities in the western Atlantic. This paper documents recent collections of P. monodon from the South Atlantic Bight and the Gulf of Mexico, reporting demographic and preliminary phylogenetic information for specimens collected between North Carolina and Texas from 2006 through 2012. The increased number of reports in 2011 and 2012, ranging from 102 mm to 298 mm total length, indicates that an adult population is present in densities sufficient for breeding, which is indicative of incipient establishment. Based on these reports of P. monodon , its successful invasion elsewhere, and its life history, we believe that this species will become common in the South Atlantic Bight and Gulf of Mexico in less than 10 years. Penaeus monodon is an aggressive predator in its native range and, if established, may prey on native shrimps, crabs, and bivalves. The impacts of an established P. monodon population are potentially widespread (e.g., alterations in local commercial fisheries, direct and indirect pressures on native shrimp, crab and bivalve populations, and subsequent impacts on the populations of other predators of those organisms) and should be considered by resource managers. The impacts of P. monodon on native fauna and the source(s) or vector(s) of the invasion, however, remain unknown at this time.

Atlantic Ocean;Gulf Of Mexico;South Atlantic Bight↗
USGS1968

Book Review: Transmission of viruses by the water route by Gerald Berg, ed.

This "book" is a collection of 31 carefully edited reports which are based upon presentations of highly qualified persons who were, for the most part, participants in a 3-day symposium held in 1965 and sponsored by the research branch of what is now the Federal Water Pollution Control Administration (FWPCA).

Transactions of the American Fisheries Society↗
USGS2010

Empirical evaluation of predator-driven diel vertical migration in Lake Superior

Recent studies on Lake Superior suggest that diel vertical migration (DVM) of prey (generalized Coregonus spp.) may be influenced by the density of predatory siscowet (Salvelinus namaycush). We empirically evaluated this hypothesis using data from acoustic, midwater trawl, and bottom trawl sampling at eight Lake Superior sites during three seasons in 2005 and a subset of sites in 2006. We expected the larger-bodied cisco (Coregonus artedi) to exhibit a shallower DVM compared with the smaller-bodied kiyi (Coregonus kiyi). Although DVM of kiyi and cisco were consistent with expectations of DVM as a size-dependent, predator-mediated process, we found no relationship between siscowet density and the magnitude of DVM of either coregonid. Cisco appear to have a size refuge from siscowet predation. Kiyi and siscowet co-occur in demersal habitat > 150 m during the day, where visual predation is unlikely, suggesting predator avoidance is not a factor in the daytime distribution of kiyi. Seasonal patterns of kiyi DVM were consistent with reported DVM of their primary prey Mysis relicta. Our results suggest that consideration of nonvisual foraging, rather than lightbased foraging theory (i.e., the antipredation window), is necessary to understand the processes driving DVM in deepwater systems.

Canadian Journal of Fisheries and Aquatic Sciences↗
USGS2011

Relationship between vegetation coverage and abundance, size, and diet of juvenile largemouth bass during winter

Juvenile largemouth bass Micropterus salmoides were collected by electrofishing during October through March 1992–1994 from coves (≤25 ha) covered with aquatic macrophytes over 1–65% of their area. Mean total length of juvenile largemouth bass was highest in coves with the least vegetated cover, but increase in mean length between October and March was highest in coves having near 20% vegetation coverage. Catch per unit effort decreased between October and March; decreases were least at vegetation coverages near 10–20%, highest at coverages of 5% or less, and intermediate at coverages of 30–65%. By March, these disparate decreases contributed to the formation of a dome-like relationship between vegetation coverage and catch per unit effort. Consumption of fish foods was highest when vegetation coverage was low, but decreased asymptotically as coverage increased; consumption of invertebrate foods increased at low coverage, peaked near 20–30% coverage, and decreased at higher coverage. We suggest that greater length increases and greater abundance at 10–25% vegetation coverage were stimulated by a favorable blend of food availability and cover. Our results support reports that maximum recruitment of largemouth bass occurs at intermediate levels of vegetation coverage, and we further suggest that such increased production is reinforced during winter, when survival. invertebrate consumption, and length increases are highest at intermediate levels of vegetation coverage.

Alabama, Mississippi↗
USGS1973

Effects of exploitation, environmental changes, and new species on the fish habitats and resources of Lake Erie

No other lake as large as Lake Erie (surface area, 25,690 km 2 ) has been subjected to such extensive changes in the drainage basin, the lake environment, and the fish populations over the last 150 years. Deforestation and prairie burning led to erosion of the watershed and siltation of valuable spawning grounds. Marsh spawning areas were drained. Lake-to-river spawning migrations of sturgeon, walleye, and other fishes were blocked by mill dams. Accelerated cultural nutrient loading increased total dissolved solids by nearly 50% (1920-70). Phosphate loading reached 469 metric tons per year by the 1950's and continued to increase. The biomass of phytoplankton increased 20-fold between 1919 and 1963. Oxygen demand for decomposition of these algae so degraded oxygen regimes in the western and central basins by the 1950's that the once abundant mayfly nymphs were destroyed and the central basin hypolimnion became anoxic. The sequence of disappearance or severe depletion of fish species was as follows: lake trout, sturgeon, lake herring, lake whitefish, sauger, blue pike, and walleye. Yellow perch are now declining. All resources were intensively exploited at one time or another. Lake trout suffered only this stress, but changes in the watershed significantly stressed sturgeon and lake whitefish. Degradation of the lake spawning grounds, benthos, and oxygen regimes culminated in severe stress by the 1950's on the remnants of the lake herring and lake whitefish, and on the sauger, blue pike, and walleye. Additional mortality may have been imposed on walleye and blue pike fry by predacious smelt that successfully colonized Lake Erie after first appearing in 1932. The cultural stresses, in the probable order of greatest to least net effects on the fish community of Lake Erie, appear to have been: (1) an intense, opportunistic, ineffectively controlled commercial fishery; (2) changes in the watershed, such as erosion and siltation of stream beds and inshore lake areas, and construction of dams in tributaries; (3) nutrient loading, destruction of biota, and reduction of dissolved oxygen; and (4) the competitive and predatory activities of invading species.

Lake Erie↗
USGS2024

Understanding and forecasting potential recruitment of Lake Michigan fishes by modeling growth and survival of larval stages with coupled climate, biophysical, and bioenergetics models

Individual adult fish can produce huge numbers of small offspring, but most die in the first weeks of life. Environmental changes that lead to even small changes in early life survival can have a disproportionate impact on the number of fish that survive and ultimately support fisheries. Lake Michigan supports valuable recreational and commercial fisheries that can fluctuate with how well fish survive in early life. Statistical models have revealed linkages between survival and climate characteristics, such as water temperature, but the exact mechanisms remain unclear and how future climate will affect the survival of young fish is highly uncertain. We integrated a series of models to investigate how climate variability may explain historical variation in the survival of young alewife and yellow perch, two fish populations that support key fisheries either directly or indirectly, while also projecting their future survival in the mid-21st century under different scenarios informed by consultation with fishery managers. Our model results revealed how spring and summer water temperatures in Lake Michigan can affect the environment in which young alewife and yellow perch grow and survive. Specifically, in years when lake warming is rapid, young fish are more likely to be transported from their natal, productive, nearshore environments to cooler and less productive offshore environments, unless adults also spawn earlier in these warm years. Furthermore, model predictions of prey abundance for young fish in the mid-21st century indicate less favorable conditions for growth and survival compared to predictions based solely on warming temperatures. With completion of the final products in the coming year, including predicted growth and survival of young fish under different future scenarios, fishery managers will have more information to share with stakeholders regarding how expectations may need to be modified regarding alewife and yellow perch productivity.

Lake Michigan↗
USGS1950

The sediments and physical environment of the Sagadahoc Bay tidal flat, Georgetown, Maine

This investigation of the sediments of the Sagadohoc Bay tidal flat was undertaken at the suggestion of the State Geologist of Maine, Dr. Joseph Thefethen, in the hope that the results might be helpful to the biologists of the Maine Department of Sear and Shore Fisheries in their studies of clam productivity and the biologists of the U.S. Fish and Wildlife Service who are making a systematic study of the ecology and potential yields of the soft-shelled clam (Mya arenaria) in Sagadohoc and neighboring bays. The field stage of the investigation lasted from early July to the end of August 1949, during which time I was assisted by W. H. Condon of the U.S. Geological Survey. This report and the accompanying map were prepared in Washington, where the laboratory studies of the sediments were made by T. Woodward of the U.S. Geological Survey.

Maine↗
USGS2005

Precipitation-runoff processes in the Feather River basin, northeastern California, and streamflow predictability, water years 1971-97

Precipitation-runoff processes in the Feather River Basin of northern California determine short- and long-term streamflow variations that are of considerable local, State, and Federal concern. The river is an important source of water and power for the region. The basin forms the headwaters of the California State Water Project. Lake Oroville, at the outlet of the basin, plays an important role in flood management, water quality, and the health of fisheries as far downstream as the Sacramento-San Joaquin Delta. Existing models of the river simulate streamflow in hourly, daily, weekly, and seasonal time steps, but cannot adequately describe responses to climate and land-use variations in the basin. New spatially detailed precipitation-runoff models of the basin have been developed to simulate responses to climate and land-use variations at a higher spatial resolution than was available previously. This report characterizes daily rainfall, snowpack evolution, runoff, water and energy balances, and streamflow variations from, and within, the basin above Lake Oroville. The new model's ability to predict streamflow is assessed. The Feather River Basin sits astride geologic, topographic, and climatic divides that establish a hydrologic character that is relatively unusual among the basins of the Sierra Nevada. It straddles a north-south geologic transition in the Sierra Nevada between the granitic bedrock that underlies and forms most of the central and southern Sierra Nevada and volcanic bedrock that underlies the northernmost parts of the range (and basin). Because volcanic bedrock generally is more permeable than granitic, the northern, volcanic parts of the basin contribute larger fractions of ground-water flow to streams than do the southern, granitic parts of the basin. The Sierra Nevada topographic divide forms a high altitude ridgeline running northwest to southeast through the middle of the basin. The topography east of this ridgeline is more like the rain-shadowed basins of the northeastern Sierra Nevada than the uplands of most western Sierra Nevada river basins. The climate is mediterranean, with most of the annual precipitation occurring in winter. Because the basin includes large areas that are near the average snowline, rainfall and rain-snow mixtures are common during winter storms. Consequently, the overall timing and rates of runoff from the basin are highly sensitive to winter temperature fluctuations. The models were developed to simulate runoff-generating processes in eight drainages of the Feather River Basin. Together, these models simulate streamflow from 98 percent of the basin above Lake Oroville. The models simulate daily water and heat balances, snowpack evolution and snowmelt, evaporation and transpiration, subsurface water storage and outflows, and streamflow to key streamflow gage sites. The drainages are modeled as 324 hydrologic-response units, each of which is assumed homogeneous in physical characteristics and response to precipitation and runoff. The models were calibrated with emphasis on reproducing monthly streamflow rates, and model simulations were compared to the total natural inflows into Lake Oroville as reconstructed by the California Department of Water Resources for April-July snowmelt seasons from 1971 to 1997. The models are most sensitive to input values and patterns of precipitation and soil characteristics. The input precipitation values were allowed to vary on a daily basis to reflect available observations by making daily transformations to an existing map of long-term mean monthly precipitation rates that account for altitude and rain-shadow effects. The models effectively simulate streamflow into Lake Oroville during water years (October through September) 1971-97, which is demonstrated in hydrographs and statistical results presented in this report.

Northeastern California↗
USGS2009

A combined telemetry - tag return approach to estimate fishing and natural mortality rates of an estuarine fish

A joint analysis of tag return and telemetry data should improve estimates of mortality rates for exploited fishes; however, the combined approach has thus far only been tested in terrestrial systems. We tagged subadult red drum (Sciaenops ocellatus) with conventional tags and ultrasonic transmitters over 3 years in coastal North Carolina, USA, to test the efficacy of the combined telemetry - tag return approach. There was a strong seasonal pattern to monthly fishing mortality rate (F) estimates from both conventional and telemetry tags; highest F values occurred in fall months and lowest levels occurred during winter. Although monthly F values were similar in pattern and magnitude between conventional tagging and telemetry, information on F in the combined model came primarily from conventional tags. The estimated natural mortality rate (M) in the combined model was low (estimated annual rate ?? standard error: 0.04 ?? 0.04) and was based primarily upon the telemetry approach. Using high-reward tagging, we estimated different tag reporting rates for state agency and university tagging programs. The combined telemetry - tag return approach can be an effective approach for estimating F and M as long as several key assumptions of the model are met.

Canadian Journal of Fisheries and Aquatic Sciences↗
USGS1960

Ovarian fluid: Its role in fertilization

FISH-CULTURISTs, in general, do not agree as to the time of actual fertilization of artificially spawned salmonid eggs. Some fish-culturists believe that the eggs are fertilized in the milt before water is added, while others are equally certain that fertilization is not achieved until after water is added. This difference of opinion has probably existed since the advent of the dry spawning method, in which milt is added to the eggs without the presence of water in the spawning pan. According to the "Manual of Fish-Culture" published by the U. S. Commission of Fish and Fisheries in 1900, it was known that eggs and milt from salmon maintain their viability for many hours if held in open containers, that both eggs and milt soon lose their viability when water is added, and that the milt and fluid around the eggs can be "utilized in impregnating masses of eggs when there is a scarcity of males, as sometimes occurs toward the close of the spawning season." The object of the studies reported here was to confirm some of the foregoing observations and to determine whether salmonid eggs could be fertilized without the supportive action of water.

Progressive Fish-Culturist↗
USGS2013

Evaluation of the behavior and movement patterns of adult coho salmon and steelhead in the North Fork Toutle River, Washington, 2005-2009

The 1980 eruption of Mount St. Helens severely affected the North Fork Toutle River (hereafter Toutle River), Washington, and threatened anadromous salmon (Oncorhynchus spp.) populations in the basin. The Toutle River was further affected in 1989 when a sediment retention structure (SRS) was constructed to trap sediments in the upper basin. The SRS completely blocked upstream volitional passage, so a fish collection facility (FCF) was constructed to trap adult coho salmon (O. kisutch) and steelhead (O. mykiss) so they could be transported upstream of the SRS. The Washington Department of Fish and Wildlife (WDFW) has operated a trap-and-haul program since 1989 to transport coho salmon and steelhead into tributaries of the Toutle River, upstream of the SRS. Although this program has allowed wild coho salmon and steelhead populations to persist in the Toutle River basin, the trap-andhaul program has faced many challenges that may be limiting the effectiveness of the program. We conducted a multi-year evaluation during 2005–2009 to monitor tagged fish in the upper Toutle River to provide information on the movements and behavior of adult coho salmon and steelhead, and to evaluate the efficacy of the FCF. Radio-tagged coho salmon and steelhead were released: (1) in Toutle River tributaries to evaluate the behavior and movements of fish released as part of the trap-and-haul program; (2) between the FCF and SRS to determine if volitional upstream passage through the SRS spillway was possible; (3) in the sediment plain upstream of the SRS to determine if volitional passage through the sediment plain was possible; and (4) downstream of the FCF to evaluate the efficacy of the structure. We also deployed an acoustic camera in the FCF to monitor fish movements near the entrance to the FCF, and in the fish holding vault where coho salmon and steelhead are trapped. A total of 20 radio-tagged coho salmon and 10 radio-tagged steelhead were released into Alder and Hoffstadt Creeks, the locations where trap-and-haul fish were released during 2005–2006. None of the tagged fish left the tributaries where they were released, but four radio tags were detected near the release sites, and it was not possible to determine if this was because the transmitters were regurgitated, or if some of the tagged fish had died. The results from this portion of the study indicated that trap-and-haul fish remain in the tributaries where they can spawn, but the trap-and-haul process is labor-intensive, and handling stress and mortality could occur. Tagged-fish releases upstream of the FCF showed that the SRS spillway was a complete migration barrier for all coho salmon and most steelhead. We released a total of 20 radio-tagged coho salmon and 23 radio-tagged steelhead during 2005–2007. No tagged coho salmon passed upstream through the SRS spillway, whereas 13 percent of the radio-tagged steelhead did migrate upstream through the structure. Radio-tagged coho salmon and steelhead that did not pass upstream remained in the FCF–SRS reach for an average of 7.5 and 16.1 d, respectively, before moving downstream. These data show that trap-and-haul releases of fish immediately upstream of the FCF would not be beneficial to coho salmon and steelhead populations in the system. Releasing tagged fish into the sediment plain was only moderately successful for coho salmon, but a large percentage of tagged steelhead moved upstream through the sediment plain to areas where spawning could presumably occur. During 2005–2009, we released 47 tagged coho salmon and 65 tagged steelhead into the sediment plain. Only 28 percent of the coho salmon were later detected upstream of the sediment plain, and the highest percentage of the release group (62 percent) never left the sediment plain. However, 69 percent of the steelhead moved upstream through the sediment plain and entered Toutle River tributaries or remained in the mainstem Toutle River where spawning could presumably occur. Adult steelhead can survive freshwater spawning, outmigrate to the ocean, and then return to spawn in successive years; 12 percent of the tagged steelhead successfully moved downstream of the FCF after the spawning period, and 5 percent of the tagged steelhead returned to the FCF a year after they were originally tagged. Evaluations at the FCF showed that the structure was not efficient at collecting adult salmon. During 2008–2009, 9 radio-tagged coho salmon and 11 radio-tagged steelhead were released to observe behavior near the facility and to estimate the recapture rate in the FCF. None of the tagged coho salmon were recaptured and only 27 percent of the tagged steelhead were recaptured. Additionally, we observed fish behavior at the FCF with an acoustic camera and found that relatively large numbers (>100 fish/sampling period) of adult salmon entered the FCF but similar numbers of fish exited during these periods as well. This suggested that the efficacy of the FCF was low. Our study was limited by the number of fish that could be handled each year and the number of transmitters that could be purchased annually, but our evaluations provided the first empirical data on adult salmon behavior and movement patterns in the Toutle River since the 1980 eruption of Mount St. Helens. Since the completion of this work, the U.S. Army Corps of Engineers has altered the SRS spillway and sediment plain; however, our results do provide information to assist fishery managers tasked with the complex management of wild salmon populations in the Toutle River. Future evaluations of juvenile and adult salmon behavior and movement likely will be required to effectively manage these populations in this complex system.

Washington↗
USGS2011

Factors influencing riverine fish assemblages in Massachusetts

The U.S. Geological Survey, in cooperation with the Massachusetts Department of Conservation and Recreation, Massachusetts Department of Environmental Protection, and the Massachusetts Department of Fish and Game, conducted an investigation of fish assemblages in small- to medium-sized Massachusetts streams. The objective of this study was to determine relations between fish-assemblage characteristics and anthropogenic factors, including impervious cover and estimated flow alteration, relative to the effects of environmental factors, including physical-basin characteristics and land use. The results of this investigation supersede those of a preliminary analysis published in 2010. Fish data were obtained for 669 fish-sampling sites from the Massachusetts Division of Fisheries and Wildlife fish-community database. A review of the literature was used to select fish metrics - species richness, abundance of individual species, and abundances of species grouped on life history traits - responsive to flow alteration. The contributing areas to the fish-sampling sites were delineated and used with a geographic information system to determine a set of environmental and anthropogenic factors that were tested for use as explanatory variables in regression models. Reported and estimated withdrawals and return flows were used together with simulated unaltered streamflows to estimate altered streamflows and indicators of flow alteration for each fish-sampling site. Altered streamflows and indicators of flow alteration were calculated on the basis of methods developed in a previous U.S. Geological Survey study in which unaltered daily streamflows were simulated for a 44-year period (water years 1961-2004), and streamflow alterations were estimated by use of water-withdrawal and wastewater-return data previously reported to the State for the 2000-04 period and estimated domestic-well withdrawals and septic-system discharges. A variable selection process, conducted using principal components analysis and Spearman rank correlation, was used to select a set of 15 non-redundant environmental and anthropogenic factors to test for use as explanatory variables in the regression analyses. Twenty-one fish species were used in a multivariate analysis of fish-assemblage patterns. Results of nonmetric multidimensional scaling and hierarchical cluster analysis were used to group fish species into fluvial and macrohabitat generalist habitat-use classes. Two analytical techniques, quantile regression and generalized linear modeling, were applied to characterize the association between fish-response variables and environmental and anthropogenic explanatory variables. Quantile regression demonstrated that as percent impervious cover and an indicator of percent alteration of August median flow from groundwater withdrawals increase, the relative abundance and species richness of fluvial fish decrease. The quantile regression plots indicate that (1) as many as seven fluvial fish species are expected in streams with little flow alteration or impervious cover, (2) no more than four fluvial fish species are expected in streams where flow alterations from groundwater withdrawals exceed 50 percent of the August median flow or the percent area of impervious cover exceeds 15 percent, and (3) few fluvial fish remain at high rates of withdrawal (approaching 100 percent) or high rates of impervious cover (between 25 and 30 percent). Three generalized linear models (GLMs) were developed to quantify the response of fluvial fish to multiple environmental and anthropogenic variables. All variables in the GLM equations were demonstrated to be significant (p less than 0.05, with most less than 0.01). Variables in the fluvial-fish relative-abundance model were channel slope, estimated percent alteration of August median flow from groundwater withdrawals, percent wetland in a 240-meter buffer strip, and percent impervious cover. Variables in the fluvial-fish species-richness model were drainage area, channel slope, total undammed reach length, percent wetland in a 240-meter buffer strip, and percent impervious cover. Variables in the brook trout relativeabundance model were drainage area, percent open water, and percent impervious cover. The variability explained by the GLM models, as measured by the pseudo R2, ranged from 18.2 to 34.6, and correlations between observed and predicted values ranged from 0.50 to 0.60. Results of GLM models indicated that, keeping all other variables the same, a one-unit (1 percent) increase in the percent depletion of August median flow would result in a 0.9-percent decrease in the relative abundance (in counts per hour) of fluvial fish. The results of GLM models also indicated that a unit increase in impervious cover (1 percent) resulted in a 3.7-percent decrease in the relative abundance of fluvial fish, a 5.4-percent decrease in fluvial-fish species richness, and an 8.7-percent decrease in brook trout relative abundance.

Massachusetts↗
USGS2008

Survival and migration behavior of juvenile coho salmon in the Klamath River relative to discharge at Iron Gate Dam, Northern California, 2007

This report describes a study of survival and migration behavior of juvenile coho salmon in the Klamath River relative to discharge at Iron Gate Dam in 2006. This was the second year of a multi-year study with the goal of determining the effects of discharge at Iron Gate Dam on survival of juvenile coho salmon downstream. The study was a collaborative effort among U.S. Geological Survey (USGS), U.S. Fish and Wildlife Service (USFWS), and the Yurok and Karuk Tribal Fisheries Departments. The goals of the study included: 1) estimating the survival of wild and hatchery juvenile coho salmon in the Klamath River downstream from Iron Gate Dam, 2) determining the effects of discharge and other covariates on their survival and migration, and 3) determining if fish from Iron Gate Hatchery could be used as surrogates for the limited source of wild fish. The major findings of the study in 2006 include: River discharges during the 2006 study period (4 April through 21 July 2006) were among the greatest on record. Average daily discharge at Iron Gate Dam was 3,956 cubic feet per second (cfs) and ranged from 997 to 10,300 cfs. Discharge at Iron Gate Dam was positively correlated with discharges of tributaries downstream due to the above average water year and frequent occurrence of spill at Iron Gate Dam. Average daily discharge near the estuary was 25,789 cfs and ranged from 4,740 to 50,600 cfs. This study was based on hatchery fish taken directly from a tank at Iron Gate Hatchery and wild fish captured in a rotary trap on the Shasta River. Releases of both groups began on 4 April when the catch of wild fish in California Department of Fish and Game‟s Shasta River rotary trap increased, but trap catches varied throughout the study period, resulting in differences in release dates of hatchery and wild fish. A total of 211 hatchery fish were released from 4 April through 26 May. Wild and hatchery fish released on a regular schedule between 25 April and 16 May 2006 were used in comparisons of the survival and migration of hatchery (N = 120) and wild (N = 162) fish. Additional analyses were performed using hatchery fish from all dates. The data and models did not support clear differences between survivals of hatchery and wild fish released on common dates, so estimates of reach survivals were made after pooling these data. Estimates of survival were lowest in the Iron Gate Dam to Scott River reach (0.813) and greatest in the Salmon River to Trinity River reach (1.000). The overall survival from river kilometer 309 (Iron Gate Hatchery) to river kilometer 33 was 0.653 (95% CI 0.578 to 0.729). Estimates of survival based on all hatchery fish releases were similar to those from release dates common to hatchery and wild fish and are similar to those in other river systems over similar distances. The migrations of hatchery and wild fish were different in the uppermost sections of the study area and were similar thereafter. A lag between release and migration, primarily upstream from the Scott River (river kilometer 234), was present in hatchery fish to a greater extent than in wild fish, resulting in differences in migration rates. Fish from both origins spent more time between release and the Scott River than in individual reaches downstream, and this was the only reach in which travel times of fish increased as discharge decreased. The travel times of hatchery and wild fish between sites were statistically similar downstream from Indian Creek (river kilometer 178). There were differences and similarities in the analyses of the effects of covariates on survivals of hatchery and wild fish. The models of covariate effects based on hatchery and wild fish released on common dates indicated effects on wild fish survival that were not supported in data from hatchery fish. However, when the entire suite of hatchery fish releases were used the results of the analyses were similar to those based on wild fish. In both instances the effects of temperature and release date were primarily in the first reach, the reach fish of both origins spent most of their time within. The signs of the effects of these covariates differed among the fish origins (negative for wild and positive for hatchery fish), presumably due to differences in their migrations in the first reach. The effects of dam discharge on survivals of hatchery and wild fish were generally similar (positive relation), and the effects on hatchery, and to a lesser extent wild, fish were largely downstream from the Scott River. This is likely due to the prolonged residence of the naïve hatchery fish, and to a lesser extent, migrant wild fish between release and the Scott River. Inasmuch as the differences between hatchery and wild fish we observed were likely those of migrants vs. non-migrants, the use of hatchery fish captured as they are migrating downstream, rather than those directly from hatchery tanks (i.e., naïve), may improve similarities between hatchery and wild fish in future studies. The data and models used in 2006 do not support the use of naïve hatchery fish as surrogates for migrant wild fish in determining the effects of discharge on survival upstream from the Scott River. This conclusion is based on the different effects of covariates in this reach that were likely attributable to the differences in hatchery and wild migration behaviors in this reach. The results of this second year of research provide insight to the migration and survival of hatchery and wild juvenile coho salmon in the Klamath River, but the results are from a single unusual water year. The results may be different during other water year types. The current information supports a positive relation between discharge at Iron Gate Dam and survival of juvenile coho salmon downstream, but additional data should be used to refine this relation. Discharge at the dam was correlated with discharges of Klamath River tributaries during this above average water year. The data and models from the 2006 study provide the first estimates of survival of these fish in the Klamath River and can be used with data from years with other water year types to examine the effects of discharge on survival. This will only be possible over a period of years in which the correlations between discharge and other factors, such as water temperature and date, are diminished. An experimental approach in which discharges are varied at Iron Gate Dam is the most direct method to determine if survivals are affected by discharge, but this may not be feasible given the limited storage capacity of the project.

California↗
USGS2020

Stock-recruitment dynamics of a freshwater clupeid

The clupeid gizzard shad Dorosoma cepedianum is often the most abundant fish species in North American reservoirs, and this dominance can have cascading trophic effects on entire fish assemblages. Accordingly, a key aspect of managing reservoir fish assemblages involves controlling gizzard shad densities. We used a 33-year time series to evaluate the relative importance of parental stock density, winter temperature, and water regime on recruitment of age-0 gizzard shad in a large reservoir. Recruitment modeled with a Ricker-type curve increased with the size of the adult stock, peaked, and then decreased at high stock densities. This over-compensatory stock-recruitment relationship was made more dynamic by fluctuations in inflow, with recruitment increasing in years of high inflow, however there was no temperature effect at the latitude of the study site. The influence of stock size on recruitment was roughly twice as high as the influence of inflow. This study is the first to report stock-recruitment relationships for a clupeid species in a reservoir and concurs with analyses of marine fishes that have shown that most clupeids exhibit compensatory or over-compensatory patterns in their stock-recruitment relationships.

Fisheries Research↗
USGS2019

Effects of water temperature, turbidity, and rainbow trout on humpback chub population dynamics

Humpback chub ( Gila cypha Miller 1946), found only in the Colorado River Basin, was one of the first species to be given full protection under the Endangered Species Act of 1973. Habitat alterations, such as changes in flow and water temperature caused by dams, and the introduction of nonnative fish have contributed to population declines in humpback chub and other native fish. These habitat alterations provide ideal conditions for the nonnative sport fish, rainbow trout ( Oncorhynchus mykiss Walbaum 1792). Managers have long sought to balance recovery of humpback chub with a viable rainbow trout fishery. However, finding this balance requires understanding how environmental conditions and rainbow trout have affected humpback chub populations. Recent findings indicate that the Colorado River can be managed for rainbow trout while maintaining a healthy humpback chub population in Grand Canyon National Park.

Arizona↗