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Research about Canada, United States

Source-linked reports with geographic coverage including Canada, United States.

At least 451 records · Page 25Linked to original sources
USGS2021

Distribution, abundance and spatial variability of microplastic pollution on the surface of Lake Superior

In 2014, 94 paired neuston net samples (0.5 mm mesh) were collected from the surface waters of Lake Superior. These samples comprise the most comprehensive surface water survey for microplastics of any of the Great Lakes to date, and the first to employ double net trawls. Microplastic abundance estimates showed wide variability, ranging between 4000 to more than 100,000 particles/km 2 with most locations having abundances between 20,000 to 50,000 particles/km 2 . The average abundance in Lake Superior was ~30,000 particles/km 2 which was similar to previous estimates within this Laurentian Great Lake and suggests a total count of more than 2.4 billion (1.7 to 3.3 billion, 95% confidence interval) particles across the lake’s surface. Distributions of plastic particles, characterized by size fraction and type, differed between nearshore and offshore samples, and between samples collected in the eastern versus western portion of the lake. Most of the particles found were fibers (67%), and most (62%) were contained in the smallest classified size fraction (0.50–1 mm). The most common type of polymer found was polyethylene (51%), followed by polypropylene (19%). This is consistent with global plastics production and results obtained from other studies. No statistically significant difference was detected between the paired net samples, indicating that single net sampling should produce a representative estimate of microplastic particle abundance and distribution within a body of water.

Lake Superior↗
USGS2021

Lake sturgeon (Acipenser fulvescens) annual adult survival estimated from acoustic telemetry

Survival of adult fishes is critical to the conservation and management of wild populations, particularly for long-lived, slow to reproduce species. Most sturgeon species are of conservation concern, but their long lifespans and large ranges have made estimation of adult survival rates challenging. In this study, acoustic telemetry was used to track 205 lake sturgeon ( Acipenser fulvescens ) tagged in the St. Clair and Detroit rivers of the Laurentian Great Lakes over seven years (2012–2019). The objective of this study was to determine if annual survival was related to sex, size, tagging location (river), or year post-tagging using Cormack-Jolly-Seber (CJS) models. Annual survival was high among all seven years (range of point estimates: 95–99%) and did not differ based on sex, tagging year, size at time of tagging, or tagging location. Lake sturgeon detection probability on acoustic receivers was high each year (range of point estimates: 82–99%) and increased as the number of receivers in the system increased. High survival rates of lake sturgeon were consistent with levels thought required for lake sturgeon to be self-sustaining in the St. Clair – Detroit river system. Our application of acoustic telemetry detections as input to CJS models demonstrated the usefulness of this approach and should be considered for population assessment studies throughout the Great Lakes and beyond.

Michigan↗
USGS2021

Slimy sculpin depth shifts and habitat squeeze following the round goby invasion in the Laurentian Great Lakes

The collapse of Diporeia spp. and invasions of dreissenid mussels (zebra, Dreissena polymorpha ; quagga, D. bugensis ) and round goby ( Neogobius melanostomus ) have been associated with declines in abundance of native benthic fishes in the Great Lakes, including historically abundant slimy sculpin ( Cottus cognatus ). We hypothesized that as round goby colonized deeper habitat, slimy sculpin avoided habitat competition, predation, and aggression from round goby by shifting to deeper habitat. Accordingly, we predicted increased depth overlap of slimy sculpin with both round goby and deepwater sculpin ( Myoxocephalus thompsonii ) that resulted in habitat squeeze by both species. We used long-term bottom trawl data from Lakes Michigan, Huron, and Ontario to evaluate shifts in slimy sculpin depth and their depth overlap with round goby and deepwater sculpin. Lake Huron most supported our hypotheses as slimy sculpin shifted to deeper habitat coincident with the round goby invasion, and depth overlap between slimy sculpin and both species recently increased. Slimy sculpin depth trends in Lakes Michigan and Ontario suggest other ecological and environmental factors better predicted sculpin depth in these lakes.

Lake Huron, Lake Michigan, Lake Ontario↗
USGS2021

An adaptive management implementation framework for evaluating supplemental sea lamprey (Petromyzon marinus) controls in the Laurentian Great Lakes

Invasive sea lamprey ( Petromyzon marinus ) populations in the Laurentian Great Lakes Basin have been suppressed for over 60 years primarily by migration barriers and lamprey-specific pesticides. Improving control outcomes by supplementing barriers and pesticides with additional control strategies has been a long-standing objective of managers and stakeholders, but progress towards this objective has been limited. We developed an adaptive management implementation framework and applied it to this objective. The framework consists of a set of adaptive management implementation goals (develop effective monitoring practices, develop effective participatory process, and conduct management experiments), a set of aspirational targets hypothesized to be related to Sea Lamprey Control Program adaptive capacity (multi-level political and social organization, creation of safe-to-fail decision making arenas, and effective use of multi-criteria decision analysis), and a feedback loop linking adaptive capacity and progress towards adaptive management implementation goals. Progress towards improving sea lamprey control outcomes by integrating supplemental control strategy into the Sea Lamprey Control Program may be possible through adaptive management implementation.

Great Lakes↗
USGS2021

A review of sea lamprey dispersal and population structure in the Great Lakes and the implications for control

Understanding the population structure of invasive sea lamprey ( Petromyzon marinus ) in the Great Lakes basin is essential for an effective control program. We review knowledge of lake connectivity, dispersal during the parasitic stage, and results from phenotypic, demographic, and genetic studies to evaluate how sea lamprey populations are structured. There is no evidence for contemporary movement between Lake Ontario and the Atlantic population, although it appears possible. Dispersal between Lake Ontario and the Finger Lakes is more likely, as is contemporary movement between Lakes Ontario and Erie via the Welland Canal, although neither has been directly observed. Downstream movement from Lake Erie to Lake Ontario via the Niagara River has been reported. Bidirectional movement between Lakes Erie and Huron has been observed, and movement of sea lamprey among the upper Great Lakes (especially between Lakes Huron and Michigan) is relatively common, although complete mixing likely does not occur. The maximum straight-line dispersal distance reported for a tagged sea lamprey was 628 km between the St. Marys River and western Lake Erie. Genetic population studies using a variety of molecular markers generally found weak but significant broad-scale population structure (e.g., between freshwater and anadromous populations, and among Lake Ontario, Lake Erie, and the upper Great Lakes), but finer-scale structure was rarely detected. Nevertheless, some within-basin structure is suggested by regional differences in phenotypic and demographic traits (e.g., sex ratio, body size). Further study will be important because management is most efficiently targeted when the geography of demographically independent populations is well-characterized.

Lake Ontario↗
USGS2021

Setting and tracking suppression targets for sea lampreys in the Great Lakes

In response to invasive species, the course of action taken by management agencies often evolves over a range of options from a do-nothing approach to suppression to complete eradication. As a case study of suppression targets, we explore the history of approaches used by the Great Lakes Fishery Commission in response to the invasion of the Laurentian Great Lakes by sea lampreys ( Petromyzon marinus ). With the early realization that eradication was not possible using available techniques, focus shifted to suppression of sea lampreys to support fish community objectives for the lakes. As a surrogate for damage to the fishery, a suppression target was defined for the maximum acceptable marking rate, indicated by the average number of sea lamprey wounds observed on every 100 large lake trout ( Salvelinus namaycush ) surveyed. Historic marking rates were used to delineate time periods of acceptable sea lamprey predation levels as an approximate measure of sea lamprey-induced mortality. A second target, independent of lake trout population status, was based on the average sea lamprey abundance estimated during the specified time periods. These intuitive targets have served as suppression benchmarks for the Sea Lamprey Control Program in the Great Lakes, allowing decision makers to gauge progress towards targets, refine control strategies and prioritize geographic areas for increased control effort. Here we document the development and subsequent changes to targets, summarize the methods used to implement these changes, and provide considerations for the future.

Great Lakes↗
USGS2021

Expansion of intertidal mussel beds following disease-driven reduction of a keystone predator

Disease shapes community composition by removing species with strong interactions. To test whether the absence of keystone predation due to disease produced changes to the species composition of rocky intertidal communities, we leverage a natural experiment involving mass mortality of the keystone predator Pisaster ochraceus from Sea Star Wasting Syndrome. Over four years, we measured dimensions of mussel beds, sizes of Mytilus californianus, mussel recruitment, and species composition on vertical rock walls at six rocky intertidal sites on the central California coast. We also assessed the relationship between changes in mussel cover and changes in sea star density across 33 sites along the North American Pacific coast using data from long-term monitoring. After four years, the lower boundary of the central California mussel beds shifted downward toward the water 18.7 ± 15.8 cm (SD) on the rock and 11.7 ± 11.0 cm in elevation, while the upper boundary remained unchanged. In central California, downward expansion and total area of the mussel bed were positively correlated with mussel recruitment but were not correlated with pre-disease sea star density or biomass. At a multi-region scale, changes in mussel percent cover were positively correlated with pre-disease sea star densities but not change in densities. Species composition of primary substrate holders and epibionts below the mussel bed remained similar across years. Extirpation of the community below the bed did not occur. Instead, this community became limited to a smaller spatial extent while the mussel bed expanded.

California, Oregon↗
USGS2021

Measuring adrenal and reproductive hormones in hair from southern Beaufort Sea polar bears (Ursus maritimus)

Polar bears ( Ursus maritimus ) use sea ice to access marine mammal prey. In Alaska’s Southern Beaufort Sea, the declining availability of sea ice habitat in summer and fall has reduced opportunities for polar bears to routinely hunt on the ice for seals, their primary prey. This reduced access to prey may result in physiological stress with subsequent potential consequences to reproductive function (physiological changes that accompany reproduction), which can be measured via reproductive hormones. Hormone concentrations in hair can be used as a minimally invasive alternative to serum concentrations, which must come from animal captures. Hair samples also provide a long-term average measurement of hormone concentrations that is not influenced by short-term fluctuations like that of serum. The aim of this study was (1) to determine if a radioimmunoassay could be used to measure adrenal and reproductive hormones in polar bear hair, and (2) to determine what the relationship is between these hormones and other reproductive, condition, and demographic parameters of polar bears. We successfully validated this method for cortisol, progesterone, estradiol, and testosterone through the analysis of hair and serum of 141 free-ranging polar bears. We found that while hair cannot be used to estimate serum hormone concentrations during the breeding season, hormone concentrations in hair can be used to measure reproductive function in polar bears. Further, our findings support trends in previous studies measuring hormone concentrations in serum. We found that adrenal and some reproductive hormones were positively correlated in hair samples of females. Associations between hormone concentrations in hair and serum did not vary relative to reproductive status of adult females. Serum testosterone increased throughout the breeding season for adult males and was significantly associated with body mass index (BMI). Our research supports the use of hair as a measure of reproductive function in polar bears and allows us to monitor the future effects of climate change on polar bear physiology.

Alaska, Yukon↗
USGS2021

Export of pelagic fish larvae from a large Great Lakes connecting channel

The St. Clair-Detroit River System is located in the heart of the North American Laurentian Great Lakes, connecting lakes Huron and Erie, contributing over 90% of the inflow to Lake Erie, and providing spawning habitat for many fishes including walleye (Sander vitreus), yellow perch (Perca flavescens), and lake whitefish (Coregonus clupeaformis). Dredging and channelization have greatly altered the Detroit River thereby reducing available spawning habitat and redirecting a majority of river discharge through deep canal-like channels to offshore areas of western Lake Erie at high velocities. Fish reproduction has been measured in the Detroit River using larval surveys for over 10 years. However, quantitative estimates of contributions from spawning in the system to Lake Erie fish populations have not been determined. We use long-term biological sampling and physical habitat surveys to characterize larval drift patterns and a Bayesian approach to quantify larval export from the Detroit River. Larval export from the Detroit River into Lake Erie varied by species, across years (2006–2015), and spatially among the multiple navigational channels in the lower Detroit River. Total annual export of walleye larvae ranged from 12 million in 2013 to 114 million in 2014, yellow perch larvae ranged from 319 million in 2014 to 690 million in 2013, and lake whitefish larvae ranged from 29 million in 2010 to 84 million in 2011. Given the widespread spawning, large numbers of larvae produced, and continued system-wide water quality and aquatic habitat improvements, the Detroit River provides valuable habitat and added resilience to Lake Erie fisheries despite suffering from severe anthropogenic disturbances.

Michigan, Ontario↗
USGS2021

Short-term survival of lake whitefish following surgical implantation of acoustic transmitters using chemical anesthesia and electroimmobilization

The recreational, tribal, and commercial importance of lake whitefish ( Coregonus clupeaformis ) has prompted interest in conducting large-scale telemetry studies to evaluate movement patterns, stock structure, and spatial distribution of fish relative to fishing effort in the Laurentian Great Lakes. However, there is a lack of knowledge concerning the postoperative effects of intracoelomic transmitter implantation and the use of different anesthetic agents and immobilization techniques during surgery on the survival of lake whitefish. Consequently, we evaluated 48-h survival of lake whitefish following intracoelomic implantation of acoustic transmitters using chemical anesthesia (i.e., Aqui-S 20E®) and electroimmobilization through a series of field surgery trials during November 2016 and 2017. Lake whitefish were collected using electrofishing and assigned to treatment groups including: 1) a loop tag; 2) a loop tag and acoustic transmitter with no anesthesia or immobilization; 3) a loop tag and transmitter using Aqui-S 20E®; 4) a loop tag and transmitter using electroimmobilization; and 5) reference fish. In treatments involving anesthesia or immobilization, induction and recovery times were recorded, and all fish were monitored for postoperative mortality. After 48 h, all fish that underwent anesthesia or immobilization during surgery were alive, but 4 of 25 (16%) fish that underwent surgery without anesthesia or immobilization died within 48 h. Induction and recovery times were substantially shorter for fish immobilized with electricity (induction time: instantaneous; recovery time < 20 s) than for those anesthetized with Aqui-S 20E® (induction time > 200 s; recovery time > 500 s). Results indicate that survival of lake whitefish following surgical implantation of acoustic transmitters was high when surgeries were conducted with Aqui-S 20E® or electroimmobilization. Compared to using Aqui-S 20E®, electroimmobilization can provide shorter induction and recovery times and may be a preferred option for field-based tagging activities with limitations on time and fish holding capacity.

Great Lakes↗
USGS2021

Spatial extent of contemporary lake whitefish spawning in western Lake Erie

Degradation of lake whitefish (Coregonus clupeaformis) spawning areas in the Detroit River, Maumee Bay, and western Lake Erie reefs and shoals has been identified as a contributing factor to Lake Erie’s population collapse in the 1950s. This decline prompted the United States and Canada to take steps to improve the aquatic ecosystem of Lake Erie. A recent increase in commercial fish harvest and catch of early-life stages of lake whitefish in the western basin of Lake Erie provide evidence that lake whitefish are once again spawning in some of their historical spawning areas, however the extent of use is unknown. To investigate the contemporary distribution of lake whitefish spawning within western Lake Erie, 31 potential spawning locations were sampled for eggs in 2016 and 2017. A subset of sites within Maumee Bay and an open lake reef complex were sampled repeatedly each year to determine the onset of spawning and 17 sites outside these two areas were each sampled once to describe the spatial extent of spawning. Spawned eggs were first detected on 22 November in 2016 and on 18 November in 2017. Viable eggs were collected at 27 of 31 sampled locations, verifying that lake whitefish spawned in Maumee Bay, on the mid-lake reefs, and other locations in 2016 and 2017. These findings confirm that lake whitefish are using historical spawning areas and available spawning habitat in western Lake Erie. The extensive use of available spawning habitat adds spawning stock diversity that is vital for generating population stability and resilience.

Lake Erie↗
USGS2021

Lake Ontario cisco population dynamics based on long-term surveys

Prior to European settlement, cisco (Coregonus artedi) were likely one of Lake Ontario’s most abundant fishes but currently represent a small portion of the fish community. To understand how the population has changed over the past 70 years we compared trends in annual catch rates from gillnet and bottom trawl surveys and commercial fishery landings. In surveys, cisco were generally rare, and represented 0.2, 0.4, and 0.001% of all fish caught in two gillnet surveys and bottom trawl surveys. Cisco catch rates in gillnets and trawls were positively correlated and correlations increased when gillnet catches two years later were compared to trawls since trawls tended to capture smaller, juvenile-sized cisco relative to gillnets. Survey catch rates suggest recruitment is generally low, but discrete periods of relatively greater recruitment in the 1980s and mid-2010s suggest reproductive conditions for cisco vary temporally. Trawl surveys were the most spatially extensive survey and illustrated catch rates were highest in northeastern Lake Ontario. Greater cisco abundance in this region may be related to more-abundant embayment spawning habitat, greater distance from winter aggregations of nonnative planktivores, or more appropriate environmental conditions during spawing. At the basin scale, Lake Ontario bottom trawl catch per unit effort (CPUE) was positively correlated to Lake Superior trawl CPUE suggesting a regional driver, such as climate, may be similarly impacting both populations. Concurrent patterns across Lake Ontario surveys support the idea that cisco are currently a small portion of the fish community, recruitment remains inconsistent, and habitats in northeastern Lake Ontario appear critical to the remnant populations.

Lake Ontario↗
USGS2021

Historic coregonine habitat use and assessment of larval nursery locations in Lake Erie

Coregonine fishes (Coregonus spp.) are important components of Great Lake food webs and support lucrative commercial and recreational fisheries. Due to a combination of several factors including habitat loss, over-exploitation, and introduction of exotic species, the distribution and abundance of coregonines have been reduced. Examples of these declines are evident in Lake Erie where cisco (C. artedi) have been nearly extirpated, and lake whitefish (C. clupeaformis), while still abundant, are declining. To identify key habitat locations of coregonines in Lake Erie, we conducted a literature review of historical spawning, nursery, and adult habitat sites where coregonines have been observed. We used these sites as a reference for larval sampling at six locations across the southern shore of Lake Erie during spring 2017. Paired bongo samplers were used to collect larvae, and average densities were calculated for comparison across sites. Larval coregonine (46 visually identified as lake whitefish; 8 classified as coregonines) densities were highest at Huron, OH (0.880/1,000 m3 ± 1.61), followed by Sandusky, OH (0.426/1,000 m3 ± 1.05), Dunkirk, NY (0.208/1,000 m3 ± 0.703), Fairport, OH (0.185/1,000 m3 ± 0.680), Erie, PA (0.120/1,000 m3 ± 0.532), and Conneaut, OH (0.1196/1,000 m3 ± 0.528). Using contemporary sampling data coupled with historical spawning locations, we identified sites that are currently being used as nursery locations by lake whitefish. By validating the contemporary use of historic spawning and nursery sites, this study identifies locations where habitat protection and restoration or future stocking of coregonids could be conducted in Lake Erie in efforts to recover populations and improve fishery production.

Lake Erie↗
USGS2021

Influence of water temperature and biotic interactions on the distribution of westslope cutthroat trout (Oncorhynchus clarkii lewisi) in a population stronghold under climate change

Climate warming is expected to have substantial impacts on native trout across the Rocky Mountains, but there is little understanding of how these changes affect future distributions of co-occurring native fishes within population strongholds. We used mixed-effects logistic regression to investigate the role of abiotic (e.g., temperature) and biotic factors (bull trout presence, Salvelinus confluentus ) on distributions of westslope cutthroat trout ( Oncorhynchus clarkii lewisi ; WCT) in the North Fork Flathead River, USA and Canada. The probability of WCT presence increased with stream temperature and decreased with channel gradient and bull trout presence, yet the effect of bull trout was reduced with increasing pool densities. Combining this model with spatially explicit stream temperature projections, we predict a 29% increase in suitable habitat under high emissions through 2075, with gains at mid-elevation sites predicted to exceed bull trout thermal tolerances and high-elevation sites expected to become more thermally suitable for WCT. Our study illustrates the importance of considering abiotic and biotic drivers to assess species response to climate change, helping to guide local-scale climate adaptation and management.

Alberta, British Columbia, Montana↗
USGS2021

Effects of a diatom ecosystem engineer (Didymosphenia geminata) on stream food webs: Implications for native fishes

Stream habitat changes affecting primary consumers often indirectly impact secondary consumers such as fishes. Blooms of the benthic algae Didymosphenia geminata (Didymo) are known to affect stream macroinvertebrates, but the potential indirect trophic impacts on fish consumers are poorly understood. In streams of the Kootenai River basin, we quantified the diet, condition, and growth rate of species of trout, char, and sculpin. In 2018, macroinvertebrate taxa composition was different between a stream with Didymo and a stream without, but trout diets, energy demand, and growth rates were similar. Trout abundance was higher in the stream with Didymo, but the amount of drifting invertebrates was higher in the stream without. In 2019, we surveyed 28 streams with a gradient of coverage. Didymo abundance was correlated only with the percentage of aquatic invertebrates in trout diets and was not related to diets of char or sculpin or condition of any species. Thus, we found no evidence for a trophic link between Didymo blooms and the condition or growth of trout, char, or sculpin in mountainous headwater streams.

Alberta, British Columbia, Idaho, Montana↗
USGS2021

It’s complicated…environmental DNA as a predictor of trout and char abundance in streams

The potential to provide inferences about fish abundance from environmental (e)DNA samples has generated great interest. However, the accuracy of these abundance estimates is often low and variable across species and space. A plausible refinement is the use of common aquatic habitat monitoring data to account for attributes that influence eDNA dynamics. We therefore evaluated the relationships between eDNA concentration and abundance of bull trout ( Salvelinus confluentus ), westslope cutthroat trout ( Oncorhynchus clarkii lewisi ) and rainbow trout ( Oncorhynchus mykiss ) at 42 stream sites in the Intermountain West (USA and Canada) and tested whether accounting for site-specific habitat attributes improved the accuracy of fish abundance estimates. eDNA concentrations were positively associated with fish abundance, but these relationships varied by species and site, and there was still considerable variation unaccounted for. Random site-level differences explained much of this variation, but specific habitat attributes of those sites explained relatively small amounts of this variation. Our results underscore that either eDNA sampling or environmental characterization will require further refinement before eDNA can be used reliably to estimate fish abundance in streams.

Idaho, Montana, Oregon, Washington↗
USGS2021

Consequences of changing water clarity on the fish and fisheries of the Laurentian Great Lakes

Human-driven environmental change underlies recent changes in water clarity in many of the world’s great lakes, yet our understanding of the consequences of these changes on the fish and fisheries they support remains incomplete. Herein, we offer a framework to organize current knowledge, guide future research, and help fisheries managers understand how water clarity can affect their valued populations. Emphasizing Laurentian Great Lakes findings where possible, we describe how changing water clarity can directly affect fish populations and communities by altering exposure to ultraviolet radiation, foraging success, predation risk, reproductive behavior, or territoriality. We also discuss how changing water clarity can affect fisheries harvest and assessment through effects on fisher behavior and sampling efficiency (i.e., catchability). Finally, we discuss whether changing water clarity can affect understudied aspects of fishery performance, including economic and community benefits. We conclude by identifying generalized predictions and discuss their implications for priority research questions for the Laurentian Great Lakes. Even though the motivation for this work was regional, the breadth of the review and generality of the framework are readily transferable to other freshwater and marine habitats.

Great Lakes↗