SEARCH · USGS Science

Results for “Growth”

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

SourceResearch connectionFrom yearThrough year

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

At least 703 records · Page 39Linked to original sources

USGS1986

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

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

North American Journal of Fisheries Management↗

USGS2000

Influence of costocking on growth of young-of-year brook trout and rainbow trout

We examined the effects of costocking on growth of hatchery-produced young-of-year brook trout Salvelinus fontinalis and rainbow trout Oncorhynchus mykiss in the laboratory. Fry of both species (brook trout = 0.16 ± 0.01 g; rainbow trout = 0.18 ± 0.01 g; mean weight ± standard deviation) were stocked into 400-L recirculation raceways at a rate of 100 fish/raceway and were held at 12°C. Raceways received either rainbow trout only ( n = 3), brook trout only ( n = 3), or half brook trout and half rainbow trout ( n = 3). Trout were fed a commercial trout feed three times per day at an initial rate of 10% body weight/d, which was reduced to 3% body weight/d by the 6th week of the study as a result of a buildup of excess feed. After 8 weeks of similar treatment, brook trout were significantly larger than rainbow trout (in terms of length and weight) when they were stocked alone. However, rainbow trout were significantly larger than brook trout (in terms of length and weight) in the costocked treatment. A second phase of the study was conducted to evaluate the effect of ration level on growth of costocked brook and rainbow trout using low (2% body weight/d), medium (4% body weight/d), and high (6% body weight/d) ration levels. After 8 weeks, rainbow trout were significantly larger than brook trout (in terms of length and weight) in all costocked feeding treatments. This suggests that behavioral interaction might have resulted in decreased growth of brook trout when they were costocked with rainbow trout.

Transactions of the American Fisheries Society↗

USGS2000

Optimum temperature for growth and preferred temperatures of age-0 lake trout

This study was performed to determine the thermal preferences and optimum temperature for growth of age-0 lake trout Salvelinus namaycush to help predict the thermal habitat they select when they leave the spawning grounds and to assess the risk posed to them in the Great Lakes by piscivorus, nonnative fishes whose thermal habitat preferences are known. The test fish were hatched in the laboratory from eggs taken from wild fish, acclimated to 5, 10, 15, and 18°C, and fed to excess with commercial trout food for 47 d. The test fish grew at all of the temperatures, and the specific growth rate was highest at about 12.5°C (3.8% wet body weight/d). Fish used in the growth study were also tested in a vertical thermal gradient tank and had a final thermal preferendum between 10.1°C and 10.2°C. These results, which generally agreed with those of an earlier laboratory study of the temperature preference of age-1 lake trout and the limited information on thermal habitat use by age-0 lake trout in the Great Lakes, indicated age-0 lake trout would tend to seek temperatures near 10°C, or as high as 12.5°C, during summer if food was abundant. Published information on thermal habitat use of age-1 and adult alewives Alosa pseudoharengus and rainbow smelt Osmerus mordax indicated they would be expected to co-occur with age-0 lake trout during much of the time when the lake trout were small enough to be eaten by these two introduced piscivores.

North American Journal of Fisheries Management↗

USGS2001

Effects of developmental stage at stocking on growth and survival of Atlantic salmon fry

Stocked fry are the primary source of fish for the restoration effort for Connecticut River Atlantic salmon Salmo salar , yet it is unknown whether there is a developmental stage at stocking that yields optimal growth and survival or whether good growth and survival can be achieved across a wide range of fry developmental stages. To evaluate the effects of developmental stage on growth and survival, we stocked otolith-marked (thermal-banding patterns) fry from four (1996) or three (1997) developmental stages (thermally delayed, nominal, thermally accelerated-fed, and thermally accelerated-unfed) into three rivers in the spring and sampled the age-0 fish in the fall. There was no difference in 1996 among delayed, nominal, or accelerated-fed developmental stage treatments in the final size or population estimate. Few fish from the accelerated-unfed treatment were recovered. Results from a laboratory starvation study suggested that fish from the accelerated-unfed treatment would die from starvation in about 4 d after release. In 1997, accelerated-fed fish were recaptured at a slightly higher rate than were fish from the delayed or nominal treatment, but final sizes did not differ among treatments. Despite differences in population estimates and sizes among rivers, there was no interaction between treatment and river in either study year, indicating that treatment effects were consistent among rivers. Our results suggest that fry from a fairly wide range of developmental stages will survive equally well and will grow to similar sizes by fall unless the fish have been accelerated without feeding.

Connecticut, Massachusetts, New Hampshire, New Yor↗

USGS2004

Comparative survival and growth of Atlantic salmon from egg stocking and fry releases

First summer survival and subsequent growth of Atlantic salmon Salmo salar planted as eggs and fry in a tributary of Cayuga Lake, New York, were examined for 3 years. Atlantic salmon were planted in December 1999-2001 in 20 Whitlock-Vibert (W-V) egg incubators, each containing 300 eyed eggs. The following May, 500 fin-clipped Atlantic salmon fry were released in the same stream section. In autumn, a backpack electroshocker was used to capture fry to assess survival and growth. Mean survival was significantly greater for fry (27.9%) than eggs (0.8%). In autumn, mean length was significantly greater for Atlantic salmon released as fry (90.1 mm) than those planted as eggs (76.2 mm), probably owing to accelerated growth in the hatchery caused by warmer water temperatures (i.e., hatchery, 9.4A?C; stream, 5.1A?C). Releasing Atlantic salmon fry in May was nearly 11 times more costly in terms of hatchery effort than was releasing eggs in December. Although the survival of Atlantic salmon eggs in W-V incubators was low, when considering production costs, the use of egg plantings may warrant consideration under certain restoration or enhancement situations.

North American Journal of Fisheries Management↗

USGS2006

Effects of increased feeding frequency on growth of hybrid bluegill in ponds

Increased feeding frequency has been used in aquaculture to increase growth and food conversion efficiency, and recent laboratory studies have indicated that feeding frequency could be used to reduce the size variation within groups of hybrid bluegills (F1: male bluegill Lepomis macrochirus x female green sunfish L. cyanellus). Our experiment evaluated the growth of pond-reared hybrid bluegills fed equal amounts of food either once or four times per day. We were particularly interested in reducing the size variation and increasing the percentage of harvestable-size fish (???110 g). After 194 d, there was no significant effect of feeding frequency on growth, food conversion efficiency, size variation, or percentage of harvestable-size fish.

North American Journal of Aquaculture↗

USGS2006

Comparison of native and introduced flathead catfish populations in Alabama and Georgia: Growth, mortality, and management

We compared growth of flathead catfish Pylodictis olivaris from two native populations in Alabama (Coosa and Tallapoosa rivers) and two introduced populations in Georgia (Ocmulgee and Satilla rivers). We also compared mortality rates and potential outcomes of various management regimes (minimum length limits [MLLs]) among the populations. Total length-log10(age) regression slopes for introduced fish were higher than those for native fish, and von Bertalanffy growth coefficients (K) were greater for introduced fish (Ocmulgee: 0.195; Satilla: 0.201) than for native individuals (Coosa: 0.057; Tallapoosa: 0.059). Therefore, introduced flathead catfish grew more rapidly than those in their native range. Mortality (instantaneous mortality rate, Z) was higher in the Satilla River population (Z = -0.602) than in the Ocmulgee River (Z = -0.227) and Coosa River (Z = -0.156) populations. However, fish in the Satilla River population had been introduced for only 10 years and presumably did not reach their theoretical maximum age, potentially biasing the mortality estimate for that population. Simulation of management regimes in Fishery Analyses and Simulation Tools software predicted that maximum biomass of flathead catfish in the Ocmulgee (1,668 kg) and Satilla (1,137 kg) rivers was substantially larger than that in the Coosa (873 kg) and Tallapoosa (768 kg) populations. However, increased exploitation rates in the Ocmulgee and Satilla River populations resulted in dramatic declines in overall biomass, especially at lower MLLs (254 and 356 mm, respectively). Therefore, in systems where introduced flathead catfish represent an important recreational fishery but have dramatically reduced the abundance of native fishes through predation, minimal protection is recommended. We contend that rapid growth of introduced flathead catfish has major implications for their management and the conservation of native fishes. ?? Copyright by the American Fisheries Society 2006.

North American Journal of Fisheries Management↗

USGS2000

Ecology and conservation of a rare, old-growth-associated canopy lichen in a silvicultural landscape

Nephroma occultum Wetm. is a rare, epiphytic lichen associated with old-growth forests of northwestern North America. We describe its distribution, abundance, and habitat within the managed landscape of a southwestern Oregon watershed. Because this species is found mainly in the canopy, we used direct canopy access (tree climbing) in combination with ground (litter) searches for our surveys. We recommend this dual approach when confident determination of presence or absence of a canopy species is needed. Our surveys confirm that N. occultum is a rare old-growth associate within the area of this study, the southernmost extension of its known range. It was both rare across the landscape and uncommon in our primary study site, a 500 yr old stand. It was most often found growing close to the trunk on branches of large Pseudotsuga menziesii , but its distribution was sporadic even within an old-growth stand. The scarcity of very old stands, in combination with the limited ability of this species to disperse within and between stands, has likely contributed to its rarity within the watershed. Management for N. occultum should focus on populations and habitat needs rather than on individuals. Our calculations show that cutting with retention of individual trees surrounded by small buffers could result in the eventual loss of N. occultum from the study area.

Oregon↗

USGS2016

Growth, survival, longevity, and population size of the Big Mouth Cave salamander ( Gyrinophilus palleucus necturoides ) from the type locality in Grundy County, Tennessee, USA

Salamander species that live entirely in subterranean habitats have evolved adaptations that allow them to cope with perpetual darkness and limited energy resources. We conducted a 26-month mark–recapture study to better understand the individual growth and demography of a population of the Big Mouth Cave Salamander ( Gyrinophilus palleucus necturoides ). We employed a growth model to estimate growth rates, age at sexual maturity, and longevity, and an open population model to estimate population size, density, detectability, and survival rates. Furthermore, we examined cover use and evidence of potential predation. Individuals probably reach sexual maturity in 3–5 years and live at least nine years. Survival rates were generally high (>75%) but declined during the study. More than 30% of captured salamanders had regenerating tails or tail damage, which presumably represent predation attempts by conspecifics or crayfishes. Most salamanders (>90%) were found under cover (e.g., rocks, trash, decaying plant material). Based on 11 surveys during the study, population size estimates ranged from 21 to 104 individuals in the ca. 710 m 2 study area. Previous surveys indicated that this population experienced a significant decline from the early 1970s through the 1990s, perhaps related to silvicultural and agricultural practices. However, our data suggest that this population has either recovered or stabilized during the past 20 years. Differences in relative abundance between early surveys and our survey could be associated with differences in survey methods or sampling conditions rather than an increase in population size. Regardless, our study demonstrates that this population is larger than previously thought and is in no immediate risk of extirpation, though it does appear to exhibit higher rates of predation than expected for a species believed to be an apex predator of subterranean food webs.

Tennessee↗

USGS2005

Long-term analysis of survival, fertility, and population growth rate of black bears in North Carolina

We estimated survival, fertility, and realized and asymptotic population growth rates from 1981 to 2002 for a protected population of black bears (Ursus americanus) in the southern Appalachian Mountains. We used Akaike's information criterion to assess the time interval for averaging observations that was best for estimating vital rates for our study, given our yearly sample sizes. The temporal symmetry approach allowed us to directly assess population growth and to address all losses and gains to the population by using only capture data, offering an alternative to the logistically intensive collection of reproductive data. Models that averaged survival and fertility across 5- and 7-year time intervals were best supported by our data. Studies of black bear populations with annual sample sizes similar to ours should be of at least 5 years in duration to estimate vital rates reliably, and at least 10 years in duration to evaluate changes in population growth rate (??). We also hypothesized that survival would not track changes in ?? because ?? is influenced by both survival and fertility. The 5-year model supported our hypothesis, but the 7-year model did not. Where long-term dynamics of large, relatively stable bear populations are of interest, monitoring survival is likely to be sufficient for evaluating trends in ??. For rapidly changing, small populations, however, failure to incorporate fertility into assessments of ?? could be misleading. ?? 2005 American Society of Mammalogists.

Journal of Mammalogy↗

USGS2014

The role of landscape features and density dependence in growth and fledging rates of Piping Plovers in North Dakota, USA

For species with precocial young, survival from hatching to fledging is a key factor influencing recruitment. Furthermore, growth rates of precocial chicks are an indicator of forage quality and habitat suitability of brood-rearing areas. We examined how growth and fledging rates of Piping Plover ( Charadrius melodus ) chicks were influenced by landscape features, such as hatchling density (hatchlings per hectare of remotely sensed habitat [H ha -1 ]), island vs. mainland, and wind fetch (exposure to waves) at 2-km segments (n ¼ 15) of Lake Sakakawea, North Dakota, during 2007–2008. Hatchling growth was comparable with published estimates for other habitats. Models for fledging rate (fledged young per segment) assuming density dependence had more support (wi ¼ 96%) than those assuming density independence (wi ¼ 4%). Density-dependent processes appeared to influence fledging rate only at densities .5 H ha -1 , which occurred in 19% of the segments we sampled. When areas with densities .5 H ha -1 were excluded, density-dependence and density-independence models were equally supported (wi ¼ 52% and 48%, respectively). Fledging rate declined as the wind fetch of a segment increased. Fledging rate on mainland shorelines was 4.3 times greater than that on islands. Previous work has indicated that plovers prefer islands for nesting, but our results suggest that this preference is not optimal and could lead to an ecological trap for chicks. While other researchers have found nesting-habitat requirements to be gravelly areas on exposed beaches without fine-grain substrates, our results suggest that chicks fledge at lower rates in these habitats. Thus, breeding plovers likely require complexes of these nesting habitats along with protected areas with fine, nutrient-rich substrate for foraging by hatchlings.

North Dakota↗

USGS2006

Survival and growth of American alligator (Alligator mississippiensis) hatchlings after artificial incubation and repatriation

Hatchling American Alligators (Alligator mississippiensis) produced from artificially incubated wild eggs were returned to their natal areas (repatriated). We compared artificially incubated and repatriated hatchlings released within and outside the maternal alligator's home range with naturally incubated hatchlings captured and released within the maternal alligator's home range on Lake Apopka, Lake Griffin, and Orange Lake in Florida. We used probability of recapture and total length at approximately nine months after hatching as indices of survival and growth rates. Artificially incubated hatchlings released outside of the maternal alligator's home range had lower recapture probabilities than either naturally incubated hatchlings or artificially incubated hatchlings released near the original nest site. Recapture probabilities of other treatments did not differ significantly. Artificially incubated hatchlings were approximately 6% shorter than naturally incubated hatchlings at approximately nine months after hatching. We concluded that repatriation of hatchlings probably would not have long-term effects on populations because of the resiliency of alligator populations to alterations of early age-class survival and growth rates of the magnitude that we observed. Repatriation of hatchlings may be an economical alternative to repatriation of older juveniles for population restoration. However, the location of release may affect subsequent survival and growth. Copyright 2006 Society for the Study of Amphibians and Reptiles.

Journal of Herpetology↗

USGS2003

Facilitation of survival and growth of Baccharis halimifolia L. by Spartina alterniflora Loisel. In a created Louisiana salt marsh

Coastal wetland loss is a major environmental issue in the Mississippi Delta region of the southern United States, where grasses such as Spartina alterniflora may play a critical role both as early colonizers on created sites and as facilitators of other marsh grasses and shrubs, particularly at high intertidal elevations. We explored the potential role of S. alterniflora as a facilitator of the colonization and growth of the shrub Baccharis halimifolia at two created wetlands in southwestern Louisiana through a combination of plant surveys and experimentation. Surveys for the presence of B. halimifolia inside and outside the bare centers of S. alterniflora clones that had begun to senesce inwardly were conducted at a 4-yr-old site originally created in 1993. The percent of clones containing B. halimifolia and the number of individual B. halimifolia plants per clone increased with increasing S. alterniflora clone size and decreased with increasing distance from an adjacent containment berm. Two experiments conducted at a second 4-yr-old site that was originally created in 1996 were designed to assess seed capture and growth of seedlings of B. halimifolia inside S. alterniflora clones. These experiments revealed that while significantly fewer seeds settle inside clones, those seedlings that grow in such areas gain a clear advantage in terms of both survival and rate of growth, which helps to explain the results of the initial survey and testifies to the role of S. alterniflora as a nurse plant in newly-created high intertidal marshes.

Louisiana↗

USGS2016

Age, growth, and size of Lake Superior Pygmy Whitefish ( Prosopium coulterii )

Pygmy Whitefish (Prosopium coulterii) are a small, glacial relict species with a disjunct distribution in North America and Siberia. In 2013 we collected Pygmy Whitefish at 28 stations from throughout Lake Superior. Total length was recorded for all fish and weight and sex were recorded and scales and otoliths were collected from a subsample. We compared the precision of estimated ages between readers and between scales and otoliths, estimated von Bertalanffy growth parameters for male and female Pygmy Whitefish, and reported the first weight-length relationship for Pygmy Whitefish. Age estimates between scales and otoliths differed significantly with otolith ages significantly greater for most ages after age-3. Maximum otolith age was nine for females and seven for males, which is older than previously reported for Pygmy Whitefish from Lake Superior. Growth was initially fast but slowed considerably after age-3 for males and age-4 for females, falling to 3–4 mm per year at maximum estimated ages. Females were longer than males after age-3. Our results suggest the size, age, and growth of Pygmy Whitefish in Lake Superior have not changed appreciably since 1953.

Lake Superior↗

USGS2007

Comparative growth and consumption potential of rainbow trout and humpback chub in the Colorado River, Grand Canyon, Arizona, under different temperature scenarios

We used bioenergetics models for humpback chub, Gila cypha, and rainbow trout, Oncorhynchus mykiss, to examine how warmer water temperatures in the Colorado River, Grand Canyon, Arizona, through a proposed selective withdrawal system (SWS) at Glen Canyon Dam, would affect growth, consumption, and predation rates. Consumption by the rainbow trout population was at least 10 times higher than by the smaller humpback chub population. Water temperature increases of 6??C during autumn increased growth of humpback chub and likely increased their survival by reducing the time vulnerable to predation. Water temperature increases caused by drought in 2005 did not alter humpback chub growth as much as the SWS. Increased temperatures might cause changes to the invertebrate community and the distribution and abundance of other warmwater nonnative fishes. The implications on the entire aquatic community need to be considered before any management action that includes increasing water temperatures is implemented.

Southwestern Naturalist↗

USGS2014

Effects of soil temperature and depth to ground water on first-year growth of a dryland riparian phreatophyte, Glycyrrhiza lepidota (American licorice)

We investigated the effects of soil temperature and depth to ground water on first-year growth of a facultative floodplain phreatophyte, Glycyrrhiza lepidota , in a 2-×-2 factorial greenhouse experiment. We grew plants in mesocosms subirrigated with water low in dissolved oxygen, mimicking natural systems, and set depth of ground water at 63 or 100 cm and soil temperature at cold (ambient) or warm (≤2.7°C above ambient). We hypothesized the moister (63 cm) and warmer soil would be most favorable and predicted faster growth of shoots and roots and greater nitrogen-fixation (thus, less uptake of mineral nitrogen) under those conditions. Growth in height was significantly faster in the moister treatment but was not affected by soil temperature. Final biomass of shoots and of roots, total biomass of plants, and root:shoot ratio indicated a significant effect only from depth of ground water. Final levels of soil mineral-nitrogen were as predicted, with level of nitrate in the moister treatment more than twice that in the drier treatment. No effect from soil temperature on level of soil-mineral nitrogen was detected. Our results suggest that establishment of G. lepidota requires strict conditions of soil moisture, which may explain the patchy distribution of the species along southwestern dryland rivers.

Southwestern Naturalist↗

USGS2018

Use of remote sensing to detect and predict aquatic nuisance vegetation growth in coastal Louisiana: Summary of findings

On an annual basis, federal and state agencies are responsible for mapping and removing large expanses of aquatic nuisance vegetation from navigable waterways. This study set out to achieve four primary objectives: (1) utilize recent advancements in remote sensing techniques to classify the extent and distribution of aquatic vegetation in coastal ecosystems using satellite imagery, (2) assess primary aquatic vegetation growth and management efforts in coastal Louisiana, (3) statistically identify the ecological drivers that promote growth and infestation of aquatic nuisance vegetation, and (4) develop numerical models and a spatial tool to predict the probability of occurrence and growth of aquatic vegetation given ecological drivers. Moderate spatial resolution multispectral satellite imagery were used in conjunction with environmental variables from available data streams to generate regression models that predict aquatic vegetation occurrence in the eastern coastal region of south Louisiana. Geospatial tools were developed to execute the model logic using recent environmental conditions, thereby predicting aquatic vegetation occurrence and producing classified maps for end users. These products provide more efficient and enhanced capabilities for management of aquatic nuisance vegetation.

Louisiana↗

USGS2011

An improved understanding of the Alaska coastal current: The application of a bivalve growth-temperature model to reconstruct freshwater-influenced paleoenvironments

Shells of intertidal bivalve mollusks contain sub-seasonally to interannually resolved records of temperature and salinity variations in coastal settings. Such data are essential to understand changing land-sea interactions through time, specifically atmospheric (precipitation rate, glacial meltwater, river discharge) and oceanographic circulation patterns; however, independent temperature and salinity proxies are currently not available. We established a model for reconstructing daily water temperatures with an average standard error of ???1.3 ??C based on variations in the width of lunar daily growth increments of Saxidomus gigantea from southwestern Alaska, United States. Temperature explains 70% of the variability in shell growth. When used in conjunction with stable oxygen isotope data, this approach can also be used to identify changes in past seawater salinity. This study provides a better understanding of the hydrological changes related to the Alaska Coastal Current (ACC). In combination with ??18Oshell values, increment-derived temperatures were used to estimate salinity changes with an average error of 1.4 ?? 1.1 PSU. Our model was calibrated and tested with modern shells and then applied to archaeological specimens. As derived from the model, the time interval of 988-1447 cal yr BP was characterized by ???1-2 ??C colder and much drier (2-5 PSU) summers. During that time, the ACC was likely flowing much more slowly than at present. In contrast, between 599-1014 cal yr BP, the Aleutian low may have been stronger, which resulted in a 3 ??C temperature decrease during summers and 1-2 PSU fresher conditions than today; the ACC was probably flowing more quickly at that time. The shell growth-temperature model can be used to estimate seasonal to interannual salinity and temperature changes in freshwater-influenced environments through time. ?? 2011 SEPM (Society for Sedimentary Geology).

Palaios↗