USGS Science⌕ Search

SEARCH · USGS Science

Results for “Canadian Journal of Fisheries and Aquatic Sciences”

Search indexed USGS publications on groundwater, aquifers, geologic maps, mineral resources and earthquakes. Explore source records by subject and place.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 361 records · Page 20Linked to original sources
USGS2008

Littoral zones as sources of biodegradable dissolved organic carbon in lakes

A survey of 12 lakes in Minnesota, USA, was conducted to examine the factors controlling variability in biodegradable dissolved organic carbon (BDOC) concentration. The principal question addressed was whether BDOC concentration was more strongly related to lake trophic status or morphometric parameters. BDOC concentration was determined by incubating filtered lake water for a period of 15 months and fitting an exponential decay curve to measured DOC concentrations. BDOC concentrations varied from 73 to 427 mmol C.L-1 and composed 15%-63% of the total DOC pool. There were no significant correlations between BDOC and measures of lake trophic status. Instead, BDOC was most closely associated with the percentage of lake area covered by littoral zone, suggesting a significant source of BDOC from aquatic macrophytes and lake surface sediments. ?? 2008 NRC.

Canadian Journal of Fisheries and Aquatic Sciences↗
USGS2008

Spatial and temporal statistical analysis of bycatch data: Patterns of sea turtle bycatch in the North Atlantic

Loggerhead (Caretta caretta) and leatherback (Dermochelys coriacea) sea turtle distributions and movements in offshore waters of the western North Atlantic are not well understood despite continued efforts to monitor, survey, and observe them. Loggerhead and leatherback sea turtles are listed as endangered by the World Conservation Union, and thus anthropogenic mortality of these species, including fishing, is of elevated interest. This study quantifies spatial and temporal patterns of sea turtle bycatch distributions to identify potential processes influencing their locations. A Ripley's K function analysis was employed on the NOAA Fisheries Atlantic Pelagic Longline Observer Program data to determine spatial, temporal, and spatio-temporal patterns of sea turtle bycatch distributions within the pattern of the pelagic fishery distribution. Results indicate that loggerhead and leatherback sea turtle catch distributions change seasonally, with patterns of spatial clustering appearing from July through October. The results from the space-time analysis indicate that sea turtle catch distributions are related on a relatively fine scale (30-200 km and 1-5 days). The use of spatial and temporal point pattern analysis, particularly K function analysis, is a novel way to examine bycatch data and can be used to inform fishing practices such that fishing could still occur while minimizing sea turtle bycatch. ?? 2008 NRC.

Canadian Journal of Fisheries and Aquatic Sciences↗
USGS2009

A biophysical model of Lake Erie walleye ( Sander vitreus ) explains interannual variations in recruitment

We used a three-dimensional coupled hydrodynamic-ecological model to investigate how lake currents can affect walleye ( Sander vitreus ) recruitment in western Lake Erie. Four years were selected based on a fall recruitment index: two high recruitment years (i.e., 1996 and 1999) and two low recruitment years (i.e., 1995 and 1998). During the low recruitment years, the model predicted that (i) walleye spawning grounds experienced destructive bottom currents capable of dislodging eggs from suitable habitats (reefs) to unsuitable habitats (i.e., muddy bottom), and (ii) the majority of newly hatched larvae were transported away from the known suitable nursery grounds at the start of their first feeding. Conversely, during two high recruitment years, predicted bottom currents at the spawning grounds were relatively weak, and the predicted movement of newly hatched larvae was toward suitable nursery grounds. Thus, low disturbance-based egg mortality and a temporal and spatial match between walleye first feeding larvae and their food resources were predicted for the two high recruitment years, and high egg mortality plus a mismatch of larvae with their food resources was predicted for the two low recruitment years. In general, mild westerly or southwesterly winds during the spawning-nursery period should favour walleye recruitment in the lake.

Canadian Journal of Fisheries and Aquatic Sciences↗
USGS2009

Genetic structure of lake whitefish (Coregonus clupeaformis) in Lake Michigan

Genetic relationships among lake whitefish (Coregonus clupeaformis) spawning aggregates in Lake Michigan were assessed and used to predict a stock or management unit (MU) model for the resource. We hypothesized that distinct spawning aggregates represented potential MUs and that differences at molecular markers underlie population differentiation. Genetic stock identification using 11 microsatellite loci indicated the presence of six genetic MUs. Resolved MUs corresponded to geographically proximate spawning aggregates clustering into genetic groups. Within MUs, analyses suggested that all but one delineated MU was a stable grouping (i.e., no between-population differences), with the exception being the Hog Island - Traverse Bay grouping. Elk Rapids was the most genetically divergent population within Lake Michigan. However, low F st values suggested that moderate to high levels of gene flow occur or have occurred in the past between MUs. Significant tests of isolation by distance and low pairwise F st values potentially led to conflicting results between traditional analyses and a Bayesian approach. This data set could provide baseline data from which a comprehensive mixed-stock analysis could be performed, allowing for more efficient and effective management of this economically and socially important resource.

Canadian Journal of Fisheries and Aquatic Sciences↗
USGS2009

Impacts of episodic acidification on in-stream survival and physiological impairment of Atlantic salmon (Salmo salar) smolts

We conducted field studies to determine the levels of acid and aluminum (Al) that affect survival, smolt development, ion homeostasis, and stress in Atlantic salmon (Salmo salar) smolts in restoration streams of the Connecticut River in southern Vermont, USA. Fish were held in cages in five streams encompassing a wide range of acid and Al levels for two 6-day intervals during the peak of smolt development in late April and early May. Physiological parameters were unchanged from initial sampling at the hatchery and the high water quality reference site (pH > 7.0, inorganic Al < 12 μg·L -1 ). Mortality, substantial loss of plasma chloride, and gill Na + /K + -ATPase activity, and elevated gill Al occurred at sites with the lowest pH (5.4-5.6) and highest inorganic Al (50-80 μg·L -1 ). Moderate loss of plasma chloride, increased plasma cortisol and glucose, and moderately elevated gill Al occurred at less severely impacted sites. Gill Al was a better predictor of integrated physiological impacts than water chemistry alone. The results indicate that Al and low pH under field conditions in some New England streams can cause mortality and impair smolt development in juvenile Atlantic salmon and provide direct evidence that episodic acidification is impacting conservation and recovery of Atlantic salmon in the northeastern USA.

Canadian Journal of Fisheries and Aquatic Sciences↗
USGS2009

Atlantic salmon (Salmo salar) smolt production: the relative importance of survival and body growth

The complex life history of Atlantic salmon (Salmo salar) coupled with interacting abiotic and biotic factors leads to extreme demographic variability across the species' range. Our goal was to evaluate the relative importance of survival and body growth in determining smolt production across space and time. We used passive integrated transponder tags and capture-mark-recapture analyses to estimate survival, emigration, and growth for six cohorts of presmolt Atlantic salmon in two streams (three cohorts per stream) in New England, USA. We observed remarkable among-cohort consistency in mean monthly survival during a 17-month period from age-0+ autumn to age-2+ spring yet high variability in monthly survival over shorter time intervals (seasons). Despite this latter variability, survival did not translate into amongcohort differences in proportions of age-2+ versus age-3+ smolts. Alternatively, the high variability across seasons and cohorts in mean individual growth rate did lead to differences in within-cohort proportions of age-2+ versus age-3+ smolts (regardless of stream). We conclude that in our two small study streams, variability in growth and size impacted smolt age and, ultimately, smolt production. Density-dependent effects on growth at the scale of the entire study site represent a possible mechanism underlying our observations.

Canadian Journal of Fisheries and Aquatic Sciences↗
USGS2009

Elemental signatures in otoliths of hatchery rainbow trout (Oncorhynchus mykiss): Distinctiveness and utility fo detecting origins and movement

Otolith chemistry in freshwater has considerable potential to reveal patterns of origin and movement, which would benefit traditional fisheries management and provide a valuable tool to curb the spread of invasive and illicitly stocked species. We evaluated the relationship between otolith and water chemistry for five markers (Ba/Ca, Mn/Ca, Sr/ Ca, Zn/Ca, and 87 Sr/ 86 Sr) in rainbow trout (Oncorhynchus mykiss) using the existing hatchery system in Colorado and Wyoming, USA, to provide controlled, seminatural conditions. Otolith Ba/Ca, Sr/Ca, and 87 Sr/ 86 Sr reflected ambient levels, whereas Mn/Ca and Zn/Ca did not. Using only the markers correlated with water chemistry, we classified fish to their hatchery of origin with up to 96% accuracy when element and isotope data were used together. Large changes in 87Sr/ Sr were evident in otolith transects, although subtler changes in Sr/Ca were also detectable. Our results suggest the relatively few otolith markers that reflect ambient chemistry can discriminate among locations and track movements well enough to provide valuable insight in a variety of applied contexts.

Canadian Journal of Fisheries and Aquatic Sciences↗
USGS2009

Using nitrogen stable isotopes to detect longdistance movement in a threatened cutthroat trout (Oncorhynchus clarkii utah)

Interior cutthroat trout occupy small fractions of their historic ranges and existing populations often are relegated to headwater habitats. Conservation requires balancing protection for isolated genetically pure populations with restoration of migratory life histories by reconnecting corridors between headwater and mainstem habitats. Identification of alternative life history strategies within a population is critical to these efforts. We tested the application of nitrogen stable isotopes to discern fluvial from resident Bonneville cutthroat trout (BCT; Oncorhynchus clarkii utah) in a headwater stream. Fluvial BCT migrate from headwater streams with good water quality to mainstem habitats with impaired water quality. Resident BCT remain in headwater streams. We tested two predictions: (i) fluvial BCT have a higher ?? 15 N than residents, and (ii) fluvial BCT ?? 15 N reflects diet and ?? 15 N enrichment characteristics of mainstem habitats. We found that fluvial ?? 15 N was greater than resident ?? 15 N and that ?? 15 N was a better predictor of life history than fish size. Our data also showed that fluvial and resident BCT had high diet overlap in headwater sites and that ?? 15 N of lower trophic levels was greater in mainstem sites than in headwater sites. We conclude that the high ?? 15 N values of fluvial BCT were acquired in mainstem sites.

Canadian Journal of Fisheries and Aquatic Sciences↗
USGS2009

Detecting declines in the abundance of a bull trout (Salvelinus confluentus) population: Understanding the accuracy, precision, and costs of our efforts

Using empirical field data for bull trout (Salvelinus confluentus), we evaluated the trade-off between power and sampling effort-cost using Monte Carlo simulations of commonly collected mark-recapture-resight and count data, and we estimated the power to detect changes in abundance across different time intervals. We also evaluated the effects of monitoring different components of a population and stratification methods on the precision of each method. Our results illustrate substantial variability in the relative precision, cost, and information gained from each approach. While grouping estimates by age or stage class substantially increased the precision of estimates, spatial stratification of sampling units resulted in limited increases in precision. Although mark-resight methods allowed for estimates of abundance versus indices of abundance, our results suggest snorkel surveys may be a more affordable monitoring approach across large spatial scales. Detecting a 25% decline in abundance after 5 years was not possible, regardless of technique (power = 0.80), without high sampling effort (48% of study site). Detecting a 25% decline was possible after 15 years, but still required high sampling efforts. Our results suggest detecting moderate changes in abundance of freshwater salmonids requires considerable resource and temporal commitments and highlight the difficulties of using abundance measures for monitoring bull trout populations.

Canadian Journal of Fisheries and Aquatic Sciences↗
USGS2009

Factors influencing coastal cutthroat trout (Oncorhynchus clarkii clarkii) seasonal survival rates: A spatially continuous approach within stream networks

Mark-recapture methods were used to examine watershed-scale survival of coastal cutthroat trout (Oncorhynchus clarkii clarkii) from two headwater stream networks. A total of 1725 individuals (???100 mm, fork length) were individually marked and monitored seasonally over a 3-year period. Differences in survival were compared among spatial (stream segment, subwatershed, and watershed) and temporal (season and year) analytical scales, and the effects of abiotic (discharge, temperature, and cover) and biotic (length, growth, condition, density, movement, and relative fish abundance) factors were evaluated. Seasonal survival was consistently lowest and least variable (years combined) during autumn (16 September - 15 December), and evidence suggested that survival was negatively associated with periods of low stream discharge. In addition, relatively low (-) and high (+) water temperatures, fish length (-), and boulder cover (+) were weakly associated with survival. Seasonal abiotic conditions affected the adult cutthroat trout population in these watersheds, and low-discharge periods (e.g., autumn) were annual survival bottlenecks. Results emphasize the importance of watershed-scale processes to the understanding of population-level survival.

Canadian Journal of Fisheries and Aquatic Sciences↗
USGS2009

Clostridium botulinum type E occurs and grows in the alga Cladophora glomerata

In recent years, massive avian die-offs from Clostridium botulinum type E infection have occurred in the Sleeping Bear Dunes National Lakeshore (SLBE) area of Lake Michigan. These outbreaks have been coincidental with massive blooms of the green algae Cladophora , mostly Cladophora glomerata . We tested the hypothesis that Clostridium botulinum type E can grow under suitable conditions in these algal mats. In a lab mesocosm study, Cladophora from four outbreak-impacted beaches from SLBE were compared with four unimpacted beaches in the Milwaukee–Racine area for bontE gene of Clostridium botulinum . Frequency of the bontE gene was higher after incubation (25 °C for up to 6 weeks) of Cladophora from impacted vs. the unimpacted area. Since no type E gene was detected initially in Cladophora from any of the eight locations, we infer that the increased occurrence of type E gene arose from spore germination or vegetative Clostridium growth within the existing algal mats of SLBE. Moreover, we found that the congener Clostridium perfringens readily grows in mesocosms containing Cladophora .

Lake Michigan;Sleeping Bear Dunes National Lakesho↗
USGS2009

The Lake Huron pelagic fish community: persistent spatial pattern along biomass and species composition gradients

Spatial patterns in the biomass of pelagic fish in Lake Huron have persisted over 10 years even though biomass decreased 86% and the fish community shifted from dominance by non-native species (rainbow smelt, Osmerus mordax) to dominance by native species (bloater, Coregonus hoyi). Based on multivariate analyses of acoustic biomass data and abiotic variables from the years 1997, 2004, 2005, and 2007, the strength of relationships between abiotic variables (primarily bottom depth) and fish community composition gradients decreased with fish biomass, suggesting that at high biomass, the influence of the measured abiotic variables is minimal. We observed consistently higher biomass in the North Channel and Georgian Bay than in the Main Basin, and as a result, we conclude that these smaller basins are likely important contributors to lakewide fish biomass, production, and dynamics. These results suggest that at current biomass levels, efforts to understand ecology, population dynamics, and lakewide abundance need to incorporate the effects of depth and geographic variation on fish distributions and ecology.

Canadian Journal of Fisheries and Aquatic Sciences↗
USGS2009

Spatial and temporal spawning dynamics of native westslope cutthroat trout, Oncorhynchus clarkii lewisi, introduced rainbow trout, Oncorhynchus mykiss, and their hybrids

We used radiotelemetry to assess spatial and temporal spawning distributions of native westslope cutthroat trout (Oncorhynchus clarkii lewisi; WCT), introduced rainbow trout (Oncorhynchus mykiss; RBT), and their hybrids in the upper Flathead River system, Montana (USA) and British Columbia (Canada), from 2000 to 2007. Radio-tagged trout (N = 125) moved upriver towards spawning sites as flows increased during spring runoff and spawned in 29 tributaries. WCT migrated greater distances and spawned in headwater streams during peak flows and as flows declined, whereas RBT and RBT hybrids (backcrosses to RBT) spawned earlier during increasing flows and lower in the system. WCT hybrids (backcrosses to WCT) spawned intermediately in time and space to WCT and RBT and RBT hybrids. Both hybrid groups and RBT, however, spawned over time periods that produced temporal overlap with spawning WCT in most years. Our data indicate that hybridization is spreading via long-distance movements of individuals with high amounts of RBT admixture into WCT streams and stepping-stone invasion at small scales by later generation backcrosses. This study provides evidence that hybridization increases the likelihood of reproductive overlap in time and space, promoting extinction by introgression, and that the spread of hybridization is likely to continue if hybrid source populations are not reduced or eliminated.

Canadian Journal of Fisheries and Aquatic Sciences↗
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↗
USGS2009

Hierarchical Bayesian analysis to incorporate age uncertainty in growth curve analysis and estimates of age from length: Florida manatee (Trichechus manatus) carcasses

Age estimation of individuals is often an integral part of species management research, and a number of ageestimation techniques are commonly employed. Often, the error in these techniques is not quantified or accounted for in other analyses, particularly in growth curve models used to describe physiological responses to environment and human impacts. Also, noninvasive, quick, and inexpensive methods to estimate age are needed. This research aims to provide two Bayesian methods to (i) incorporate age uncertainty into an age-length Schnute growth model and (ii) produce a method from the growth model to estimate age from length. The methods are then employed for Florida manatee (Trichechus manatus) carcasses. After quantifying the uncertainty in the aging technique (counts of ear bone growth layers), we fit age-length data to the Schnute growth model separately by sex and season. Independent prior information about population age structure and the results of the Schnute model are then combined to estimate age from length. Results describing the age-length relationship agree with our understanding of manatee biology. The new methods allow us to estimate age, with quantified uncertainty, for 98% of collected carcasses: 36% from ear bones, 62% from length.

Canadian Journal of Fisheries and Aquatic Sciences↗
USGS2009

Performance of temperature and dissolved oxygen criteria to predict habitat use by lake trout (Salvelinus namaycush)

We compared theoretical habitat volumes, determined from traditional combinations of temperature and dissolved oxygen concentration (DO) boundaries, with in situ habitat use by acoustically tagged lake trout ( Salvelinus namaycush ). The widely used criteria of 8–12 °C underestimated lake trout habitat use by 68%–80%. Instead, combined temperature (<12 or 15 °C) and DO (>4 or 6 mg·L –1 ) criteria most closely matched lake trout habitat use, had a similar seasonal trend as the tagged fish, suggested modest reductions (5% of total lake volume) in habitat during a warmer year, and performed best when the constraints of temperature and DO were most limiting. All data were collected in a small boreal shield lake (27 ha, z max = 21 m) at the Experimental Lakes Area in northwestern Ontario, Canada, during two contrasting periods of thermal stratification (2003: warmer and longer; 2004: cooler and shorter), providing an assessment of observed and theoretical habitat volumes over current environmental extremes.

Canadian Journal of Fisheries and Aquatic Sciences↗
USGS2009

Spatiotemporal dynamics of the Atlantic salmon (Salmo salar) Greenland fishery inferred from mixed-stock analysis

Mixed-stock fisheries refer to the exploitation of admixed fish stocks coming from different origins. We identified the North American origin of 2835 Atlantic salmon (Salmo salar) in the Greenland mixed-stock fishery during 11 years (1995-2006) at three localities using 13 microsatellites. The study included 52 baseline populations representing nine genetically distinct regional groups. The contribution of each group ranged from <1% (Maine) to 40% (Southern Qu??bec). Decreasing temporal contributions were observed for Southern Qu??bec (-22.0%) and New Brunswick (-17.4%), whereas an increasing contribution for Labrador (+14.9%) was observed during the time course of the study. The estimated regional contribution to the Greenland fishery was significantly correlated to the number of multi-sea-winter salmon regionally produced in 2002 (r = 0.79) and 2004 (r = 0.92). No difference in contribution was found between the three Greenland sampling localities. Ungava and Southern Qu??bec regions showed the highest mortality estimates caused by the fishery, ranging from 12.10% to 18.08%, for both years tested. No regional group was overrepresented in landings compared with their respective productivity. Yet, management precautions should still be taken as the fishery strongly selects large females, which could have evolutionary impacts on populations over the long term.

Canadian Journal of Fisheries and Aquatic Sciences↗
USGS2010

Individual and colony-specific wintering areas of Pacific northern fulmars (Fulmarus glacialis)

Seabird mortality associated with longline fishing in the eastern Bering Sea occurs mainly from September to May, with northern fulmars (Fulmarus glacialis) comprising the majority (60%) of the bycatch. Along the west coast of North America, winter dieoffs of fulmars may be increasing in frequency and magnitude, the most severe on record being a wreck that peaked in October-November 2003. We deployed satellite transmitters on fulmars from the four main Alaska colonies and tracked individuals for up to 2 years. Fulmars from Hall Island (northern Bering Sea) moved to Russian coastal waters after breeding, while Pribilof Island fulmars (southeastern Bering Sea) remained relatively sedentary yearround. Birds from Chagulak Island (eastern Aleutians) preferred passes between the Aleutian Islands in winter or foraged widely over deep waters of the central Bering Sea and North Pacific. Fulmars from the Semidi Islands (western Gulf of Alaska) migrated directly to waters of the California Current. Individuals from St. George Island (Pribilofs) and Chagulak were consistent in the places that they visited in two successive winters. The Pribilof Islands population is most affected by winter longlining for groundfish, whereas the Semidi Islands colony sustains most of the natural mortality that occurs off Washington, Oregon, and California.

Alaska↗