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At least 397 records · Page 22Linked to original sources
USGS2022

Final report: Understanding historical and predicting future lake temperatures in North and South Dakota

Lakes, reservoirs, and ponds are central and integral features of the landscape of the North Central US. These water bodies provide aesthetic, cultural, and ecosystem services to surrounding wildlife and human communities. Lakes are warming, resulting in the loss of many native fish. In order to manage economically valuable fisheries and other ecosystem services provided by lakes, it is important for managers to have access to accurate estimates of water temperature to better understand past change and to plan for potential future further warming. These data are invaluable for making decisions such as whether to continue stocking plans as usual in certain lakes or how to set specific harvest limits. This project developed new state-of-the-art methods to model historical thermal habitat for thousands of lakes in the Midwest US.

North Dakota, South Dakota↗
USGS2019

Potential threats facing a globally important population of the magnificent frigatebird Fregata magnificens

Tracking of seabirds has been used to identify foraging hotspots, migratory routes and to assess at-sea threats facing populations. One such threat is the potential negative interaction between seabirds and fisheries through incidental by-catch. In 2012, 60 magnificent frigatebirds Fregata magnificens were found dead, entangled in fishing line, at the globally important breeding site in the British Virgin Islands (BVI). To assess the potential relationship between foraging behaviour and fishing activity, data loggers were deployed on breeding magnificent frigatebirds to record foraging movements. In addition, a survey of local fishers was conducted to assess the scale of incidental by-catch. We recorded 28 complete foraging trips from GPS and GPS-GSM loggers, and 1758 PTT locations. Birds travelled up to 3.3–1067 km from their breeding colony and entered the waters of 10 neighbouring territories. A high percentage of fishers (93% n = 28) reported catching at least one seabird annually, of which the most common were magnificent frigatebirds and brown boobies Sula leucogaster . There are estimated to be at least 1112 vessels in the recreational and artisanal fishing fleets of BVI and its neighbouring islands. Thus, this substantial fishery may have potentially profound effects on seabird populations in the region.

Tropical Zoology↗
USGS2018

Development of new information to inform fish passage decisions at the Yale and Merwin hydro projects on the Lewis River, Washington—Final report, 2018

The reintroduction of extirpated salmonids to historically occupied areas is becoming increasingly common as a conservation and recovery strategy. Often, reintroductions are implemented after the factors that originally led to species extirpation have been reduced, eliminated, or mitigated. For anadromous Oncorhynchus spp. (Pacific salmon) and O. mykiss (steelhead), addressing barriers to migration, which have been a primary factor in the decline and extirpation of many populations, has been an integral component of recovery efforts. Mitigation has included barrier removal, developing fish passage opportunities, and (or) actively trapping and hauling juvenile and adult anadromous salmonids around barriers. With any reintroduction, there are a number of concerns regarding the ecological impact of the reintroduction efforts. Three of the main tenets to consider when assessing reintroductions are (1) the potential benefits if reintroduction is successful, (2) the biological risk through interactions of reintroduced strains with existing populations, and (3) the factors potentially limiting a successful reintroduction. This report focuses on information and data to address the second and third factors as they apply to the upper Lewis River in Washington. The upper Lewis River historically contained wild populations of O. tshawytscha (Chinook salmon), O. kisutch (coho salmon), and steelhead. These populations were extirpated after completion of hydropower facilities on Lake Merwin in 1932, Yale Lake in 1953, and Swift Reservoir in 1958, which prevented fish from migrating to and from ocean environments. However, recent licenses issued by the Federal Energy Regulatory Commission require the installation and operation of an upstream fish passage facility at Lake Merwin and a downstream fish passage facility at Swift Reservoir. The licenses were developed in consultation with the National Marine Fisheries Service and the U.S. Fish and Wildlife Service. The overarching goal of this fish reintroduction project is to establish viable, self-sustaining, naturally reproducing, harvestable populations of spring Chinook salmon, winter steelhead, and coho salmon at levels higher than minimum viable populations. This report uses a combination of field data and existing information to address six key objectives related to the reintroduction in order to inform decisions about passage at the Yale Lake and Lake Merwin hydropower projects. The objectives are (1) a review of information relevant to anadromous fish reintroduction and full fish passage; (2) a habitat assessment of tributaries to Swift Reservoir, Yale Lake, and Lake Merwin; (3) a field study to assess adult potential for spawning success; (4) an assessment of juvenile production and outmigration success; (5) a Lake Merwin predator impact study; and (6) a set of studies assessing interactions between anadromous and resident fish.

Washington↗
USGS2023

Evolutionary and ecological correlates of thiaminase in fishes

Thiamine (vitamin B 1 ) is required by all living organisms in multiple metabolic pathways. It is scarce in natural systems, and deficiency can lead to reproductive failure, neurological issues, and death. One major cause of thiamine deficiency is an overreliance on diet items containing the enzyme thiaminase. Thiaminase activity has been noted in many prey fishes and linked to cohort failure in salmonid predators that eat prey fish with thiaminase activity, yet it is generally unknown whether evolutionary history, fish traits, and/or environmental conditions lead to production of thiaminase. We conducted literature and GenBank BLAST sequence searches to collect thiaminase activity data and sequence homology data in expressed protein sequences for 300 freshwater and marine fishes. We then tested whether presence or absence of thiaminase could be predicted by evolutionary relationships, trophic level, omega-3 fatty acid concentrations, habitat, climate, invasive potential, and body size. There was no evolutionary relationship with thiaminase activity. It first appears in Class Actinoptergyii (bony ray-finned fishes) and is present across the entire Actinoptergyii phylogeny in both primitive and derived fish orders. Instead, ecological factors explained the most variation in thiaminase: fishes were more likely to express thiaminase if they fed closer to the base of the food web, were high in polyunsaturated fatty acids, lived in freshwater, and were from tropical climates. These data provide a foundation for understanding sources of thiaminase leading to thiamine deficiency in fisheries and other organisms, including humans that eat uncooked fish.

Scientific Reports↗
USGS2018

Modeling White Sucker (Catostomus commersonii) populations to assess commercial harvest influence on age structure

Commercial harvest of White Suckers Catostomus commersonii for bait in the American Lobster Homarus americanus industry is minimally regulated in Maine and there are concerns as to the influence of increasing harvest. We built a population model using parameters (i.e. age-specific mortality, age at maturity, and size-specific fecundity) from literature and field studies to investigate the theoretical effects of harvest mortality on age structure. Because stock-recruitment relations are poorly characterized for this species, we explored the influence of both Beverton-Holt and Ricker recruitment processes. Our base model closely resembled the empirical age structures reported from three unfished lakes in Maine, with four percent of fish in the modeled spawning run being age-10 or older. We assessed the additive effects of harvest mortality on age structure using the full range of possible mortalities. As expected, increased harvest mortality in the model resulted in a decline and disappearance of older age-classes such that few fish greater than age-10 remained in the population under a realistic harvest mortality scenario. This age-truncation was qualitatively comparable to data from aggregate age distributions reported from three commercially harvested lakes in Maine. Because the loss of older fish may compromise population viability, this model is a valuable guidance tool for managers to craft regulation of this growing fishery.

Maine↗
USGS2021

A decade of Indigenous knowledge research in the Yukon River basin: Reflection on “Indigenous observations of change in the lower Yukon River basin, Alaska”

Herman-Mercer reflects on her first article" Indigenous Observations of Change in the Lower Yukon River Basin, Alaska." The observations and knowledge presented in this study have become part of an ever-growing catalog of studies representing, and part of a chorus of Indigenous communities across the Arctic and Subarctic conveying, the impacts of climate change in this region. The broad observations of environmental change reported in Indigenous Observations 2011, including impacts to subsistence and safety, are more dire and apparent than ten years ago when this article was published. Instances of diseased salmon continue to be reported by subsistence fishers, and the salmon runs have declined so severely since Indigenous Observations 2011 was published that there have been several years in which the commercial and or the subsistence salmon fishery was closed on the Yukon River, with impacts to household economies, food security, and culture. The then-new dangers associated with travel on river ice continue to be a concern across the Yukon River where the thinner river ice and inconsistent freeze up and break up have become the norm.

Alaska↗
USGS2012

The Columbia River Research Laboratory

The mission of the Columbia River Research Laboratory is to serve the public by providing scientific information to support the stewardship of our Nation's fish and aquatic resources, with emphasis on the Columbia River basin. As a part of the U.S. Geological Survey (USGS) Western Fisheries Research Center, we conduct objective, relevant research and seek partnerships to help fulfill this mission.

Fact Sheet↗
USGS1975

The determination, assessment, and design of "in-stream value" studies for the northern Great Plains region

An extensive literature review was conducted to determine the discharge requirements of various components of a warm water fishery. Where exact hydrologic parameters were not measured directly in individual studies, they were estimated from inferred statements and knowledge of hydrologic variables leading to certain instream conditions. From this information it was possible to determine which components of the stream community would be most seriously affected by reduced discharges. In addition, a number of different methods used in the recommendation of minimum streamflows was reviewed. These methods were evaluated for their reliability and ease of use. It was concluded that a method for recommending minimum discharges should not sacrifice reliability for expediency. A methodology is proposed for the recommendation of minimum discharges for a warm water fishery. This method utilizes field measurements of critical stream areas and biological criteria determined from the used of indicator species. For large rivers, migration and spawning requirements are analyzed using the paddlefish ( Polyodon spathula ) as the indicator species. For smaller rivers, the suggested indicator species is the sauger ( Stizostedion canadense ). Rearing flows are determined on the basis of stream productivity by analyzing macroinvertebrate habits, and on the basis of fish habitat typing. The indicator species for determining adequate fish habitat is the stonecat ( Notorus flavus ). A number of variables were identified which might require a greater amount of in-stream flow than the fishery, per se. These variables included streamflow needs for riparian and other sub-irrigated vegetation, water quality parameters, anchor ice formation, and the relationship between discharge and sediment yield. Information concerning these variables is insufficient at this time to determine whether a variable will "over-ride" the streamflow requirement for the fishery itself. Further research is needed in these areas, and several investigative methods for conducting such research are proposed.

Great Plains↗
USGS2020

Kelp forest monitoring at Naval Base Ventura County, San Nicolas Island, California: Fall 2017 and Spring 2018, Fourth Annual Report

To assess and track changes to the rocky subtidal communities surrounding San Nicolas Island, the U.S. Navy entered into an agreement with the U.S. Geological Survey (USGS) in 2014 to conduct an ecological monitoring program at several sites around the island. Four permanent sites—Nav Fac 100, West End, Dutch Harbor, and Daytona 100—were established. The sites were based on ones that had been monitored since 1980 by USGS and were combined or expanded for better comparability with monitoring programs conducted at the other California Channel Islands. At the sites, scientists from USGS and our cooperator, the University of California, Santa Cruz, measured bottom cover of algae and sessile invertebrate species in quadrats, counted and sized fish on swimming transects, and counted a suite of kelps and invertebrates on benthic band transects. Holdfast diameter and number of stipes of giant kelp ( Macrocystis pyrifera ) were recorded on these transects, and size data were collected for urchins, sea stars, and shelled mollusks. Bottom temperatures were recorded at hourly intervals by archival data loggers that were deployed at the sites. This report focuses primarily on data collected in fall 2017 and spring 2018 and makes comparisons with data collected in previous years, beginning in fall 2014. Nav Fac 100 is a site with a relatively low benthic profile, situated on the north side of San Nicolas Island. It was previously urchin dominated but underwent a dramatic decline in purple sea urchins in 2015 and 2016. Since then, macroalgae has become more prevalent as both annual brown algae, such as Dictyota, and perennials (for example, Cystoseira ) have become established. The invasive brown alga Sargassum horneri has also become established. West End, on the southwest side of the island, also lacks much bottom relief but has more crevice habitat associated with boulders. It remains dominated by kelps and red algae, but red algae have decreased recently. Dutch Harbor, on the south side, has many high relief rocky reefs and had the greatest fish and non-motile invertebrate densities. It remains the most stable of the sites. Daytona 100, on the southeast side, has moderate relief and has remained a patchwork of kelp and urchin dominated areas with moderate fish density. The main change at the sites during the last 4 years was the decline in urchin numbers at Nav Fac 100. There was storm-related mortality and subsequent recruitment in the M. pyrifera population at several of the sites in both 2016 and 2017. The winter of 2018, however, was relatively mild, with less destructive storm-related disturbance. The invasive brown alga S. horneri , first seen at San Nicolas Island at Nav Fac 100 in fall 2015, has become firmly established there during the last 2 sampling years. Finally, moderate increases were observed in purple urchin densities at all sites this spring. Long-term data are presented to illustrate trends and changes over the past three decades. Results indicate continued monitoring to evaluate ecosystem effects from perturbations owing to natural processes and anthropomorphic factors, including recovery of the sea otter population, changes in fisheries, invasive species and changing environmental conditions, could be valuable to inform managers’ decision-making.

California↗
USGS2012

February 2012 workshop jumpstarts the Mekong Fish Monitoring Network

The Mekong River in Southeast Asia travels through a basin rich in natural resources. The river originates on the northern slope of the world's tallest mountains, the Himalaya Range, and then drops elevation quickly through steep mountain gorges, tumbling out of China into Myanmar (Burma) and the Lao People's Democratic Republic (Lao PDR). The precipitous terrain of Lao PDR and Thailand generates interest in the river and its tributaries for hydropower development. The terrain, soils, water, and climate make it one of the world's most biologically rich regions. The Mekong's bounty is again on display in the Mekong River Delta, where rice production has successfully been increased to high levels making Vietnam second only to Thailand as the world's largest rice exporters. At least 800 fish species contribute to the natural resource bounty of the Mekong River and are the basis for one of the world's most productive fisheries that provide the primary protein source to more than 50 million people. Against this backdrop of rich natural resources, the U.S. Geological Survey (USGS) is working with the consulting firm FISHBIO, colleagues from the international Delta Research and Global Observation Network (DRAGON) Institute, and a broad contingent of Southeast Asian representatives and partners from abroad to increase knowledge of the Mekong River fisheries and to develop the capacity of permanent residents to investigate and understand these fisheries resources. With the Lower Mekong Basin (LMB) region facing the likelihood of significant environmental changes as a result of both human activities and global climate change, enhancing environmental understanding is critical. To encourage cooperation among the LMB scientists and managers in the study of the Mekong River's fisheries, FISHBIO and the USGS, with generous support from the U.S. State Department, hosted a workshop in Phnom Penh, Cambodia, in February 2012. Workshop participants were from Lao PDR, Thailand, Cambodia, and Vietnam. Representatives from the governments, universities, nongovernmental organizations, and the Mekong River Commission discussed current and potential methods and mechanisms of the Mekong Fish Monitoring Network. The goals of the workshop were to determine if the Network and associated databases were of interest and value to the LMB nations, to determine if future fisheries monitoring data would be comparable among the nations, and to establish methods and an organizational structure for collaborating on future monitoring and research. The participants in this international workshop agreed that the Network would be useful but would require additional funding to secure their full participation. The USGS and FISHBIO are collaboratively seeking additional funding to expand research participation and projects in all four LMB nations. If the Network can facilitate cooperation among many fisheries researchers in the LMB, the basin would become a model of cooperative international fishery studies and would increase the understanding of a river basin rich in natural resources.

Phnom Penh↗
USGS2013

Seventy-five years of science—The U.S. Geological Survey’s Western Fisheries Research Center

As of January 2010, 75 years have elapsed since Dr. Frederic Fish initiated the pioneering research program that would evolve into today’s Western Fisheries Research Center (WFRC). Fish began his research working alone in the basement of the recently opened Fisheries Biological Laboratory on Lake Union in Seattle, Washington. WFRC’s research began under the aegis of the U.S. Fish and Wildlife Service and ends its first 75 years as part of the U.S. Geological Survey with a staff of more than 150 biologists and support personnel and a heritage of fundamental research that has made important contributions to our understanding of the biology and ecology of the economically important fish and fish populations of the Nation. Although the current staff may rarely stop to think about it, WFRC’s antecedents extend many years into the past and are intimately involved with the history of fisheries conservation in the Western United States. Thus, WFRC Director Lyman Thorsteinson asked me to write the story of this laboratory “while there are still a few of you around who were here for some of the earlier years” to document the rich history and culture of WFRC by recognizing its many famous scientists and their achievements. This historyalso would help document WFRC’s research ‘footprint’ in the Western United States and its strategic directions. Center Director Thorsteinson concluded that WFRC’s heritage told by an emeritus scientist also would add a texture of legitimacy based on personal knowledge that will all-to-soon be lost to the WFRC and to the USGS. The WFRC story is important for the future as well as for historical reasons. It describes how we got to the place we are today by documenting the origin, original mission, and our evolving role in response to the constantly changing technical information requirements of new environmental legislation and organizational decision-making. The WFRC research program owes its existence to the policy requirements of Federal conservation legislation originating with the construction of Grand Coulee Dam in 1933. The research program was shaped by laws enacted in subsequent years such as the Federal Water Pollution Control Act (1972), National Environmental Policy Act (1973), Endangered Species Act (1974), and Northwest Power Planning Act (1980), to name only a few. The WFRC has not been constrained by direct management or regulatory responsibility for a particular fishery (such as providing sustainable catch limits data to a resource management structure). Thus, WFRC has been able to concentrate on scientific pursuits and information needs required by contemporary environmental legislation. Over the years, we have pioneered in several important areas of fisheries research including the diagnoses and control of diseases in economically important fish, effects of environmental alterations on the physiological quality and survival of Pacific salmon released from federal mitigation hatcheries, applications in biotelemetry, and the bioenergetics of predator-prey interactions in the Columbia River. The WFRC of today is a widely distributed organization in the Western United States. Knowledge of the historical connections and accomplishments of our predecessors is important beyond the sense of pride and unity it instills in the WFRC family of today. For example, a discerning reader will note the evolution of WFRC’s research from a single disciplinary focus (early era—hatchery disease problems), to multiple disciplines (middle to late era—species, populations, habitats; threatened and endangered species), to the present era (multidisciplinary and with increasing process focus). For the benefit of the current WFRC staff, more emphasis has been placed on the early years rather than on the present day because people are quite naturally more familiar with the recent past than with the research done during the first decades of WFRC’s existence. By every rational measure, the WFRC has evolved into a fisheries research organization well positioned to provide the biological information needed to support the continued conservation and management of our Nation’s living aquatic natural resources. The high standard of excellence that connects WFRC’s past to our present research program provides a firm foundation on which to base the work yet to be done. In another 75 years, WFRC will undoubtedly be a very different place than it is today, but its evolution will be forever rooted in the story of the research and of the people related here. More about the diverse fisheries research projects WFRC scientists are conducting today is available at WFRC’s website: http://wfrc.usgs.gov/.

Washington↗
USGS2016

Construction, calibration, and validation of the RBM10 water temperature model for the Trinity River, northern California

We constructed a one-dimensional daily averaged water-temperature model to simulate Trinity River temperatures for 1980–2013. The purpose of this model is to assess effects of water-management actions on water temperature and to provide water temperature inputs for a salmon population dynamics model. Simulated meteorological data, observed streamflow data, and observed water temperatures were used as model inputs to simulate a continuous 34-year time series of historical daily mean water temperature at eight locations along 112.2 river miles from Lewiston Dam near Weaverville, California, downstream to the Klamath River confluence. To demonstrate the utility of the model to inform management actions, we simulated three management alternatives to assess the effects of bypass flow augmentation in a drought year, 1994, and compared those results to the simulated historical baseline, referred to as the “No Action” alternative scenario. Augmentation flows from the Lewiston Dam bypass consist of temperature-controlled releases capable of cooling downstream water temperatures in hot times of the year, which can reduce the probability of disease outbreaks in fish populations. Outputs from the Trinity River water-temperature model were then used as inputs to an existing water-temperature model of the Klamath River to evaluate the effect of augmentation flow releases on water temperatures in the lower Klamath River. We structured the Trinity River water-temperature model in River Basin Model-10 (RBM10), which uses a simple equilibrium flow model, assuming discharge in each river segment on each day is transmitted downstream instantaneously. The model uses a heat-budget formulation to quantify heat flux at the air-water interface. Inputs for the heat budget are calculated from daily mean meteorological data, including net shortwave solar radiation, net longwave atmospheric radiation, air temperature, wind speed, vapor pressure, and a psychrometric constant needed to calculate the Bowen ratio. The modeling domain was divided into eight reaches ranging in length from 8.8 to 20.6 miles, which were calibrated and validated separately with observed water temperature data collected irregularly from 1980 to 2013. Root mean square errors of observed and simulated water temperatures for the eight reaches ranged from 0.25 to 1.12 degrees Celsius (°C). Mean absolute errors ranged from 0.18 to 0.89 °C. For model validation, a k -fold cross-validation technique was used. Validation root mean square error and mean absolute error for the eight reaches ranged from 0.24 to 1.11 °C and from 0.18 to 0.89 °C, respectively. Augmentation scenarios were based on historical hydrological and meteorological data, combined with prescribed flow and temperature releases from Lewiston Dam provided by the Bureau of Reclamation. Water releases were scheduled to achieve targeted flows of 2,500, 2,800, and 3,200 cubic feet per second in the lower Klamath River from mid-August through late September, coinciding with the upstream migration of adult fall-run Chinook salmon ( Oncorhynchus tshawytscha ). Water temperatures simulated at river mile 5.7 on the Klamath River showed a 5 °C decrease from the No Action historical baseline, which was near or greater than 23 °C when augmentation began in mid-August. Thereafter, an approximate 1 °C difference among augmentation scenarios emerged, with the decrease in water temperature commensurate to the level of augmentation. All augmentation scenarios simulated water temperatures equal to or less than 21 °C from mid-August through late September. Water temperatures equal to or greater than 23 °C are of particular interest because of a thermal threshold known to inhibit upstream migration of salmon. When temperatures exceed this approximate 23 °C threshold, Chinook salmon are known to congregate in high densities in thermal refugias and show extended residence times, which can potentially trigger epizootic outbreaks such as of Ichthyophthirius multifiliis (“Ich”) and Flavobacterium columnare (“Columnaris”) that were the causative factors of the Klamath River fish kill in 2002. A model with the ability to simulate water temperatures in response to management actions at the basin scale is a valuable asset for water managers who must make decisions about how best to use limited water resources, which directly affect the state of fisheries in the Klamath Basin.

California↗
USGS2000

Hydrology, water quality, and nutrient loads to Lake Catherine and Channel Lake, near Antioch, Lake County, Illinois

From April 21, 1998, through April 30, 1999, the U.S. Geological Survey, in cooperation with the Fox Waterway Agency, conducted an investigation designed to characterize the hydrology, water quality, hydrologic budget, sediment budget, and nutrient budget of Lake Catherine and Channel Lake, Lake County, Illinois. These lakes are the northernmost lakes of the Fox Chain of Lakes. Lake Catherine and Channel Lake are divided into two basins by a submerged ridge but are continuous at the surface. The lakes are marginally to moderately eutrophic. Lake Catherine and Channel Lake have a combined volume of 7,098 acre-feet at a stage of about 736.5 feet above sea level. Lake Catherine and Channel Lake are subject to thermal stratification. Although most of the water in the lakes is well oxidized, nearly anoxic conditions were present at the bottom of Lake Catherine and Channel Lake during part of the summer in 1998. Water enters Lake Catherine and Channel Lake as inflow from surface water in the watershed (61.9 percent), inflow through the State Highway 173 bridge openings (20.7 percent), direct precipitation (8.2 percent), inflow from storm drains (7.2 percent), and inflow of ground water (2.0 percent). Water exits Lake Catherine and Channel Lake as outflow through the State Highway 173 bridge openings (87.8 percent), evaporation (7.2 percent), and as outflow to ground water (5.0 percent). About 5,200 pounds of phosphorus and 107,200 pounds of nitrogen compounds were added to the lakes during the period of investigation. Phosphorus compounds were derived from primarily internal regeneration (40.2 percent), inflow from surface water in the watershed (30.9 percent), inflow from storm drains (12.5 percent), and inflow through the State Highway 173 bridge openings (9.8 percent). Inflowing ground water, waterfowl excrement, precipitation, and atmospheric deposition of particulate matter account for 6.6 percent of the phosphorus load. Nitrogen was derived from inflow of surface water from within the watershed (52.9 percent), internal regeneration (19.5 percent), inflow through the State Highway 173 bridge openings (10.7 percent), precipitation (7 percent), and inflow from storm drains (6.5 percent). Inflowing ground water, waterfowl excrement, and atmospheric deposition of particulate matter account for about 3.4 percent of the nitrogen load. About 2,220 pounds of phosphorus and 52,300 pounds of nitrogen compounds are removed from the lakes, primarily through the openings at State Highway 173. Nitrate, nitrite, ammonia, and dissolved phosphorus are utilized by algae and aquatic macrophytes. Uptake of these nutrients by aquatic macrophytes and algae temporarily removes them from the water column but not from the lake basin. Because the amount of nutrients entering the lake greatly exceeds the amount leaving, the nutrients are concentrated in the sediments at the lake bottom, where the nutrients can be used by the rooted aquatic macrophytes (rooted aquatic plant large enough to be visible to the unaided eye) and released to the water column during reducing conditions. The buildup of nitrogen and phosphorus compounds in the lakes has the potential over time to stimulate algal and plant growth to nuisance levels that have the potential to affect the fishery and detract from the aesthetic quality of these lakes.

Water-Resources Investigations Report↗
USGS2000

Preliminary hydraulic analysis and implications for restoration of Noyes Slough, Fairbanks, Alaska

The present-day channels of the Chena River and Noyes Slough in downtown Fairbanks, Alaska, were formed as sloughs of the Tanana River, and part of the flow of the Tanana River occupied these waterways. Flow in these channels was reduced after the completion of Moose Creek Dike in 1945, and flow in the Chena River was affected by regulation from the Chena River Lakes Flood Control Project, which was completed in 1980. In 1981, flow in the Chena River was regulated for the first time by Moose Creek Dam, located about 20 miles upstream from Fairbanks. Constructed as part of the Chena River Lakes Flood Control Project, the dam was designed to reduce maximum flows to 12,000 cubic feet per second in downtown Fairbanks. Cross-section measurements made near the entrance to Noyes Slough show that the channel bed of the Chena River has been downcutting, thereby reducing the magnitude and duration of flow in the slough. Consequently the slough slowly is drying up. Residents of the community wish to restore flow in Noyes Slough to create a clean, flowing waterway during normal summer flows. The desire is to enhance the slough as a fishery and habitat for other wildlife and for recreational boating.

Alaska↗
USGS2003

Pop-up archival transmitting (PAT) tags: A method to investigate the migration and behavior of Pacific halibut ( Hippoglossus stenolepis ) in the Gulf of Alaska

Pop-up archival transmitting (PAT) tags provide a fisheries-independent method of collecting environmental preference data (depth and ambient water temperature) and migration distance. In this study, we evaluate the use of pop-up archival transmitting tags as a method to investigate demersal fish. We report the results from eight pop-up archival transmitting tagged Pacific halibut Hippoglossus stenolepis (from 107 to 165 cm FL) that were released in and around Resurrection Bay, Alaska. Commercial fishermen recovered three tags, while five tags transmitted data to Argos satellites. Horizontal migration was not consistent among fish as four Pacific halibut remained in the vicinity of release while the other four traveled up to 358 km from the release site. Vertical movement was not consistent among fish or over time; however, they spent most of their time at depths of 150 to 350 m. The minimum and maximum depths reached by any of the Pacific halibut were 2 m and 502 m, respectively. The fish preferred water temperatures of approximately 6°C, but experienced temperatures between 4.3 and 12.2°C. Light attenuation with depth prevented geolocation software and light sensing hardware from accurately estimating geoposition for the majority of days. The methods, adapted from investigations on large pelagic fish, proved to be effective for studying Pacific halibut in the northern Gulf of Alaska. PAT tags allowed us to obtain high accuracy locations of the fish at the end of the tag deployments as well as preliminary data to identify approximate seasonal locations and to characterize their depth and temperature characteristics. By using PAT tags, we will be able to ensure tag returns during the winter season (which is closed to fishing) and gain valuable biological information even if fish migrate large distances or to unexpected locations.

Alaska Fishery Research Bulletin↗
USGS2010

Effects of High-Flow Experiments from Glen Canyon Dam on Abundance, Growth, and Survival Rates of Early Life Stages of Rainbow Trout in the Lees Ferry Reach of the Colorado River

High-flow experiments (HFEs) from Glen Canyon Dam are primarily intended to conserve fine sediment and improve habitat conditions for native fish in the Colorado River as it flows through Grand Canyon National Park, Arizona. These experimental flows also have the potential to affect the rainbow trout (Oncorhynchus mykiss) population in the Lees Ferry tailwater reach immediately below the dam, which supports a highly valued recreational fishery and likely influences the abundance of rainbow trout in Grand Canyon. Understanding how flow regimes affect the survival and growth of juvenile rainbow trout is critical to interpreting trends in adult abundance. This study reports on the effects of HFEs in 2004 and 2008 on early life stages of rainbow trout in the Lees Ferry reach on the basis of monthly sampling of redds (egg nests) and the abundance of the age-0 trout (fertilization to about 1 to 2 months from emergence) and their growth during a 7-year period between 2003 and 2009. Multiple lines of evidence indicate that the March 2008 HFE resulted in a large increase in early survival rates of age-0 trout because of an improvement in habitat conditions. A stock-recruitment analysis demonstrated that age-0 abundance in July 2008 was more than fourfold higher than expected, given the number of viable eggs that produced these fish. A hatch-date analysis showed that early survival rates were much higher for cohorts that hatched about 1 month after the 2008 HFE (about April 15, 2008) relative to those fish that hatched before this date. These cohorts, fertilized after the 2008 HFE, would have emerged into a benthic invertebrate community that had recovered, and was possibly enhanced by, the HFE. Interannual differences in growth of age-0 trout, determined on the basis of otolith microstructure, support this hypothesis. Growth rates in the summer and fall of 2008 (0.44 mm/day) were virtually the same as in 2006 (0.46 mm/day), the highest recorded during 6 years, even though abundance was eightfold greater in 2008. We speculate that the 60-hour-long 2008 HFE (with peak magnitude about twice that of the annual peak flow during the previous 4 years) increased interstitial spaces in the gravel bed substrate and food availability or quality, leading to higher early survival of recently emerged trout and better growth of these fish through summer and fall. Abundance in 2009 was more than twofold higher than expected, given the estimated number of viable eggs deposited in that year, perhaps indicating that the effect of the 2008 HFE on early life stages was somewhat persistent. In a 3-week interval that spanned the November 2004 HFE, abundance of age-0 trout that were approximately 7 months old from hatch experienced about a threefold decline, compared to the approximately twofold decrease observed between November and December 2008. Abundance of age-0 trout that were approximately 10 months old from hatch was very similar across sampling trips that spanned the March 2008 HFE. It is uncertain whether the decline in abundance after the November 2004 HFE was the result of higher flow-induced mortality or higher flow-induced downstream dispersal. A focused monitoring effort in Marble Canyon (the reach immediately downstream of the Lees Ferry tailwater) before and after future HFEs is recommended to resolve this uncertainty. Relatively detailed monitoring of early life stages-such as the program described in this study-is essential to establish linkages between Glen Canyon Dam operations, or possibly other factors, and trends in the abundance of important nonnative and native fish populations living downstream within Grand Canyon National Park.

Open-File Report↗
USGS2012

Perils of correlating CUSUM-transformed variables to infer ecological relationships (Breton et al. 2006; Glibert 2010)

We comment on a nonstandard statistical treatment of time-series data first published by Breton et al. (2006) in Limnology and Oceanography and, more recently, used by Glibert (2010) in Reviews in Fisheries Science. In both papers, the authors make strong inferences about the underlying causes of population variability based on correlations between cumulative sum (CUSUM) transformations of organism abundances and environmental variables. Breton et al. (2006) reported correlations between CUSUM-transformed values of diatom biomass in Belgian coastal waters and the North Atlantic Oscillation, and between meteorological and hydrological variables. Each correlation of CUSUM-transformed variables was judged to be statistically significant. On the basis of these correlations, Breton et al. (2006) developed "the first evidence of synergy between climate and human-induced river-based nitrate inputs with respect to their effects on the magnitude of spring Phaeocystis colony blooms and their dominance over diatoms."

Limnology and Oceanography↗
USGS2009

Influence of a weak field of pulsed DC electricity on the behavior and incidence of injury in adult Steelhead and Pacific Lamprey

Predation by pinnipeds, such as California sea lions Zalophus californianus, Pacific harbor seals Phoca vitulina, and Stellar sea lions Eumetopias jubatus on adult Pacific salmon Oncorhynchus spp in the lower Columbia River has become a serious concern for fishery managers trying to conserve and restore runs of threatened and endangered fish. As a result, Smith-Root, Incorporated (SRI; Vancouver, Washington), manufacturers of electrofishing and closely-related equipment, proposed a project to evaluate the potential of an electrical barrier to deter marine mammals and reduce the amount of predation on adult salmonids (SRI 2007). The objectives of their work were to develop, deploy, and evaluate a passive, integrated sonar and electric barrier that would selectively inhibit the upstream movements of marine mammals and reduce predation, but would not injure pinnipeds or impact anadromous fish migrations. However, before such a device could be deployed in the field, concerns by regional fishery managers about the potential effects of such a device on the migratory behavior of Pacific salmon, steelhead O. mykiss, Pacific lampreys Entoshpenus tridentata, and white sturgeon Acipenser transmontanus, needed to be addressed. In this report, we describe the results of laboratory research designed to evaluate the effects of prototype electric barriers on adult steelhead and Pacific lampreys.

Report↗