Food habits of young-of-year largemouth bass in Lake Mead and Lake Mohave, Arizona-Nevada

Young-of-year largemouth bass from lakes Mead and Mohave fed upon crustacean zooplankton, insects (primarily chironomids), and fish. Largemouth bass smaller than 32 mm TL fed extensively upon zooplankton. In Lake Mead, transition to an insect-dominated diet occurred at 32 mm TL; transition to an insect-fish—dominated diet did not occur in Lake Mohave until a length of 56 mm was reached. Largemouth bass from Lake Mohave consumed significantly more zooplankton than did those from Lake Mead, but largemouth bass from Lake Mead consumed significantly more insects. Fish were most common in the diet of young-of-year largemouth bass larger than 52 mm TL.     

Distribution and relative abundance of fish in Ruth Reservoir, California, in relation to environmental variables

The fish population of Ruth Reservoir, California, was sampled every two weeks with variable mesh gill nets from May 1974 through May 1975. Fish were captured in the following order of numerical abundance: Humboldt sucker ( Catostomus humboldtianus ), golden shiner ( Notemigonus crysoleucus ), brown bullhead ( Ictalurus nebulosus ), white catfish ( I. catus ), rainbow trout ( Salmo gairdneri ), and largemouth bass ( Micropterus salmoides ). The three most abundant species made up about 95 percent of total numbers and weight. All species exhibited a similar cyclic temporal availability pattern: catch rates increased to a maximum during summer and fall and decreased during winter and spring. Environmental variables with the most pronounced relationships to fish catches were temperature (direct) and turbidity (inverse).     

Status and life history notes on the native fishes of the Alvord Basin, Oregon and Nevada

Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4 st1\:*{behavior:url(#ieooui) } /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;} Three fishes, two species of Gila, and an undescribed subspecies of cutthroat trout, are endemic to the Alvord Basin. Historically, the Alvord cutthroat trout, Salmo clarki ssp., inhabited the larger creeks of the basin but has been extirpated in pure form because of introgression with introduced rainbow trout, Salmo gairdneri. Gila boraxobius is restricted to the thermal waters of Borax Lake and its outflows in the northern part of the basin. This species is endangered because of alteration of its fragile habitat. The Alvord chub, G. alvordensis, is recorded from 16 localities throughout the basin, including springs, creeks, and reservoirs. Although G. alvordensis as a species is not in jeopardy, many populations are small and could be easily eliminated by habitat destruction or by the introduction of exotic fishes. Competition with exotic guppies, Poecilia reticulata, has extirpated the Thousand Creek Spring population of Alvord chubs. Both species of Gila are opportunistic omnivores, consuming primarily chironomids, microcrustaceans, and diatoms. The Borax Lake chub also consumed large numbers of terrestrial insects, but specialized feeding on molluscs was noted in the West Spring population of Alvord chubs. Borax Lake chubs spawn throughout the year; however, most spawning occurs in early spring. Borax Lake chubs mature at a small size, occasionally less than 30 mm standard length, and seldom live more than one year. Alvord chubs are typically much larger than the Borax Lake species and live at least into their fifth year.     

Egg production of two sympatric species of Hyalella Smith, 1874 (Crustacea,Amphipoda, Dogielinotidae) in aquaculture ponds in southern Brazil

This study tests the hypothesis that sympatric species of Hyalella may show different reproductive strategies that permit their coexistence. Ovigerous females were collected monthly with nets during a 1-year period in two aquaculture trout ponds in Vale das Trutas, São José dos Ausentes County, southern Brazil. In both species there was a decrease in the number of embryos in the brood pouch during embryonic development, and an increase in egg volume. However, the two species differed in the body size of ovigerous females, number of eggs and juveniles per female, brood mortality rate, egg size and hatching size of juveniles. Egg production continued throughout the year, with the highest number of eggs produced during winter and spring by Hyalella pleoacuta, and winter, spring and autumn by Hyalella castroi. These differences in the reproductive traits of species of Hyalella may permit their coexistence in nature.     

Predation of adult razorback sucker and bonytail by striped bass in Lake Mohave, Arizona–Nevada

We report 2 separate records from sport-fish anglers in Lake Mohave, Arizona–Nevada, that document the presence of endangered razorback sucker Xyrauchen texanus and bonytail Gila elegans in stomach contents of large (13+ kg) nonnative striped bass Morone saxatilis. These records suggest that striped bass, since their first appearance in Lake Mohave nearly 3 decades ago, may have played a role in population declines of the other 2 species. Current native-fish stocking programs at Lake Mohave continue to face significant obstacles to achieving population recoveries because all life stages of repatriated individuals, including mature adults, are vulnerable to predation.     

Littoral heterogeneity and diel behavior of white bass ( Morone chrysops ) and carp ( Cyprinus carpio ) in Utah Lake, Utah

Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4 st1\:*{behavior:url(#ieooui) } /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;} Diel activity and association patterns of white bass ( Morone chrysops ) and carp ( Cyprinus carpio ) in Utah Lake, Utah, were studied over four 24-hr periods during August 1980. Fish were concurrently sampled from two adjacent littoral habitats. Significant differences existed in diel activity patterns in two of three size classes of white bass and in diel association patterns of white bass and carp between the two habitat areas. Differences in habitat structure, and in biological activity between the habitat types, are implicated as the primary determinants of overall diel activity of fish in these littoral areas.        

Trichoptera and other macroinvertebrates in springs of the Great Basin: species composition, richness, and distribution

Detailed surveys of aquatic invertebrates in 28 springs along the western border of the Great Basin were made using pan traps, emergence traps, black lights, and benthic sampling devices from 1994 to 1998. Although all macroinvertebrate groups were collected, caddisflies (Insecta: Trichoptera) were sampled most intensively. Fifty-eight species of caddisflies were collected from the 28 springs, with up to 18 species from a single spring. Although several springs had very similar physicochemical characteristics, none had identical trichopteran species composition. Using Wards minimum variance clustering technique, and with all macroinvertebrates identified to the lowest possible level, we found 3 taxa assemblages. These assemblages occurred in springs with the following physical conditions: (1) warm water (15.9° C), low elevation (1794 m); (2) cold water (8.5° C), mid-elevation (2334 m); and (3) cold water (6.6° C), high elevation (1794 m). Although the warm water group had a distinct assemblage of invertebrates (amphipods, gastropods, Trichoptera), distinct assemblages did not separate the 2 cold water groups. Discriminant analysis indicated that temperature, conductivity, alkalinity, and elevation were most responsible for discriminating group 1 from groups 2 and 3; temperature and elevation distinguished the latter 2 groups. Spring permanence, lack of disturbance, and cold water temperatures were the factors most responsible for explaining higher species richness of Trichoptera.     

Composition and abundance of periphyton and aquatic insects in Sierra Nevada, California, stream

The species composition of periphyton and benthic insect communities and abundances of common taxa (&;gt;0.1&;#37; of individuals) were examined during snow-free months in Convict Creek, a permanent snowmelt- and spring-fed stream in the Sierra Nevada of California. The communities were highly diverse. The most abundant taxa in the periphyton were diatoms ( Achnanthes minutissima, Cocconeis placentula lineata, Cymbella microcephala, C. sinuata, Fragilaria construens, F. crotonensis , Navicula spp., Synedra acus , and S. rumpens ), except in late spring and summer when several seasonal blue-green algae ( Chamaesiphon incrustans, Lyngbya spp. and Oscillatoria spp.) are at their maximum densities. Most common periphyton taxa vary systematically in abundance with season, but relative abundances of taxa also appear to be influenced by streambed scouring and by concentrations of ambient nutrients. Data on population densities and length frequencies of larval and nymphal stages of common benthic insects and occurrences of pupal and adult stages were examined to determine life history patterns. Taxa hatching in winter and spring and abundant as immatures in late spring include ephemeropterans ( Epeorus longimanus, Drunella flavilinea , and Caudatella heterocaudata ), plecopterans ( Calineuria californica, Doroneuria baumanni, and Pteronarcys princeps ) and dipterans ( Cryptolabis sp.). Common taxa hatching in late spring or summer are the plecopteran Malenka ( californica? ) and the trichopterans Arctopsyche grandis and Rhyacophila acropedes . Several bivoltine and multivoltine ephemeropterans ( Baetis devinctus and B. tricaudatus ) and dipterans ( Simulium spp. and Chironomidae) have summer cohorts. Taxa hatching in late summer or autumn and most abundant in autumn include ephemeropterans ( Baetis spp., Ephemerella infrequens, Epeorus dulciana, Ironodes lepidus , and Paraleptophlebia pallipes ), trichopterans ( Hydropsyche oslari, Lepidostoma spp., Glossosoma califica, Micrasema sp., Brachycentrus americanus, Neophylax sp., and Rhyacophila vaccua ) and dipterans ( Antocha monticola, Pericoma sp., and Chironomidae). Major recurring events that may influence life history patterns and structure of the benthic insect community are (1) near-freezing, nighttime winter water temperatures and occasional anchor ice, (2) a prolonged period of high discharge in late spring and early summer (3) a brief summer, and (4) a prolonged period of moderate stream discharge in autumn when the substratum is stable and food is abundant.     

Daily activity of the white-clawed crayfish,Austropotamobius pallipes (Lereboullet): a comparison between field and laboratory studies

The daily activity of the threatened crayfish, Austropotamobius pallipes (Lereboullet), was studied both in the field, through direct counts of active animals along a stream section, and in the laboratory, by means of actographs. In the field, crayfish were mostly found after dawn, with a slight but significant difference among seasons. In winter, only two specimens were seen to be active. Distinguishing among size classes, medium-sized crayfish were more abundant in spring and summer, while large ones mostly occurred in autumn. The former always concentrated their activity at night-time; to the contrary, larger specimens were more active late at night in spring and at dusk in autumn. Sex-ratio, analysed only in summer, was balanced throughout the 24h. Nocturnal activity, although differing among seasons, was similar in size classes, temperatures and sexes. In the laboratory, activity (evaluated as photo-cell interruptions) increased with temperature and occurrence throughout a 24-h cycle (the highest peak shifting from midnight to dusk). Only in the laboratory, a low peak occurred at dawn, but disappeared when a shelter was available. The interaction between the response of A. pallipes to temperature and its nocturnal habit is examined. Questions still remain on the adaptive value of the environmental factors influencing the cycle of freshwater decapods' activity.     

Management of endangered Sonoran topminnow at Bylas Springs, Arizona: description, critique, and recommendations

Efforts between 1982 and 1990 have failed to recover and secure three natural populations of endangered Sonoran topminnow ( Poeciliopsis o. occidentalis ) at Bylas Springs, Arizona. Flooding in the Gila River in 1977-78 allowed ingress by predatory mosquitofish ( Gambusia affinis ), and topminnows began to decline. Since that time (1) one stock has been replaced twice and is again nearly gone because of depredations by mosquitofish that resisted two eradication attempts; (2) topminnows at a second spring were extirpated through vegetation encroachment after fencing to protect the habitat from livestock; and (3) a third population was lost to mosquitofish, restocked after the nonnative was removed, and the restocked population is again in jeopardy, or extirpated, since mosquitofish reinvaded. Recommendations for a more intensive program of recovery are based on reassessments of past efforts and new suggestions for eradication and exclusion of mosquitofish.     

Ecological studies of a regulated stream: Huntington River, Emery County, Utah

A 36.9x10 6 m 3 reservoir constructed on Huntington River, Emery County, Utah, resulted in changes in physical habitat, water quality, temperature, and flow regime. The greatest changes in physical habitat resulted from: (1) sediment additions from dam and road construction plus erosion of reservoir basin during filling; and (2) changing stream flow from a spring high runoff regime to a moderated flow regime. Elimination of spring nutrient concentration peaks and overall reduction of total dissolved nutrient availability in the river plus moderate reductions in pH were the most apparent water quality changes below the reservoir. Water temperature changes were an increased diurnal and seasonal constancy, summer depression, and winter elevation, generally limited to a 10–12 km reach below the dam. Physical and chemical changes altered macroinvertebrate community structure, with changes greatest near the dam and progressively less as distance downstream increased. Below the dam: (1) more environmentally tolerant taxa increased their dominance; (2) relative numbers of smaller sized individuals increased in relation to larger individuals; and (3) filter feeding, collector/gatherers, and scrapers gained an advantage over shredders. Insect taxa such as Rhithrogena robusta, Pteronarcella badia, and Ephemerella doddsi were eliminated from stream reaches near the dam, and other taxa such as Arctopsyche grandis, Chironomidae, and Simuliidae increased in numbers. Late spring to early summer egg hatch proved to be a disadvantage to Brachycentrus occidentalis, and B. americanus, with a fall hatch, was less impacted by altered river flow patterns. Macroinvertebrate taxa with small instar larvae present from late summer to early fall were negatively impacted by the unnaturally high July and August flows. The reservoir became a physical barrier to downstream larval drift and upcanyon and downcanyon immigration of adults, resulting in reduced numbers of several species above and below the reservoir.         

Growth of smallmouth bass ( Micropterus dolomieu ) in Flaming Gorge Reservoir, Wyoming-Utah

Growth of smallmouth bass ( Micropterus dolomieu ) was described for three widely spaced areas progressing downstream in Flaming Gorge Reservoir, Wyoming-Utah. Significant differences among areas were detected only for age-1 fish. Growth in the reservoir was compared with that of populations in other lentic habitats of varying growing season lengths in North America; slow growth in the reservoir was related to the relatively short growing season (less than 90 days).     

Status of introduced fishes in certain spring systems in southern Nevada

We record eight species of exotic fishes as established, reproducing populations in certain springs in Clark, Lincoln, and Nye counties. Nevada. These include an unidentified species of Hypostomus, Cyprinus carpio, Poecilia mexicana, Poecilia reticulata, a Xiphophorus hybrid, and Cichlasoma nigrofasciatum. Tilapia mariae, established in a spring near the Overton Arm of Lake Mead, and Tilapia zilli, established in a golf course pond in Pahrump Valley, are recorded for the first time from Nevada waters. Though populations of transplanted Gambusia affinis persist, other populations of Poecilia latipinna are apparently no longer extant. Cichlasoma severum, Notemigonus crysoleucas, Poecilia latipinna, and Carassius auratus were apparently eradicated from Rogers Spring in 1963.     

Distribution of a thermal endemic minnow, The desert dace ( Eremichthys acros ), and observations of impacts of water diversion on its population

Population status surveys were performed from 1987 to 1996 for desert dace ( Eremichthys acros , a cyprinid endemic to several small thermal springs in Soldier Meadow, Humboldt County, Nevada, where the species occupies 7 spring areas in a single valley. Because spring distributions are patchy and all areas are not linked by surface flow, each area comprises a more-or-less isolated population, although irrigation practices or high runoff may occasionally link several of them. Although limited to thermal springpools and outflows, desert dace were found in temperatures ranging from 37° C near spring sources to 13° C in downstream areas. Between May 1988 and October 1989, most of the discharge from a major spring outflow was diverted from its natural channel into an irrigation ditch than in the channel. Reduced fish numbers still persist (1996), even though the affected site has been relatively undisturbed since 1989. To improve desert dace habitat and increase populations, irrigation diversion should be discontinued and water returned to the original channel. Continued protection and increased habitat preservation for desert dace are recommended because of their limited distribution, apparently restricted habitat requirements, and the potential for environmental disruption in the area.     

Spring waterfowl migration in the Uinta Basin of northeastern Utah

Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4 st1\:*{behavior:url(#ieooui) } /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;} Spring waterfowl migrations at Ouray National Wildlife Refuge and Pelican Lake, Uintah County, Utah, were monitored during 1975 and 1976. Peak numbers occurred during the first week in April 1975 when 11,440 birds were counted. In 1976 the highest count, 9,650 birds, was made on 15 March. Most numerous earlyseason migrants were Mallards and Pintails. Important midseason migrants included Blue - winged and Cinnamon Teal, Canvasbacks, and Redheads. Late season migrants were Gadwall and Ruddy Ducks. Surveys conducted only at Ouray Refuge or at Pelican Lake would not adequately have reflected species composition of spring migration. Results point up the advisability of sampling large open water areas to obtain a representative view of waterfowl species composition in a given area during spring migration.        

Food habits of clouded salamanders ( Aneides ferreus ) in Curry County, Oregon (Amphibia: Caudata: Plethodontidae)

Stomach contents of 650 clouded salamanders ( Aneides ferreus ), collected monthly throughout the year from Curry County, Oregon, were examined. Samples from three age classes were involved: (1) 489 adults, (2) 131 juveniles, and (3) 30 hatchlings. Foods did not vary by sex, but did vary by age and by season. Hatchlings ate small items, particularly mites, springtails, flies, and small beetles. Juveniles fed mainly on flies, isopods (sowbugs), beetles, mites, and centipedes in winter; beetles, ants, and isopods in spring; ants and beetles in summer; and isopods, beetles, and ants in fall. Adults ate isopods and beetles as their major foods in winter, spring, and fall and isopods, ants, beetles, and earwigs in summer. Four species were exceedingly important as foods for these salamanders: an unidentified isopod, the snout beetle ( Trachyphloeus bifoveatus ), the European earwig ( Forficula auricularia ), and an ant ( Lasius alienus ).       

Impact of cattle on two isolated fish populations in Pahranagat Valley, Nevada

The presence of cattle at Browning Spring and Ash Springs in Pahranagat Valley, Nevada, impacted fish populations by causing an increase in ammonia (NH 3 ) and nitrite (NO 2 ) levels, an increase in Pseudomonas aeruginosa and Aeromonas hydrophila , and increased, mortality and morbidity. One of the affected fishes, the White River springfish, is listed as endangered by the Department of the Interior. After removal of the cattle from Ash Springs, NH 3 and NO 2 levels decreased and fish populations increased. At Brownie Spring the NH 3 and NO 2 levels are chronically elevated, cattle are still present, and the speckled dace population has not recovered.     

Diatom flora of Cowboy Hot Spring, Mono County, California

The diatom flora of Cowboy Hot Spring, Mono County, California, was studied. Two habitats, one at 37C and one at 41C, were examined. Fifty-six taxa were identified from our samples. These taxa were mostly broadly distributed forms, and no endemic species were encountered. The dominant taxon was Nitzschia frustulum, followed by Achnanthes gibberula, Achnanthes exigua, Nitzschia hantzschiana , and Navicula cincta .     

Life history, abundance, and distribution of Moapa dace ( Moapa coriacea )

Moapa dace ( Moapa coriacea ) is a federally listed endangered fish endemic to the spring-fed headwaters of the Muddy River, Clark County, Nevada. Species life history, abundance, and distribution were studied from March 1984 to January 1989. Reproduction, which was observed year-round, peaked in spring and was lowest in fall. It occurred in headwater tributaries of the Muddy River within 150 m of warm water spring discharge in water temperatures ranging from 30 to 32 C. Females matured between 41 and 45 mm in fork length (FL). Egg abundance increased with female size ( r 2 = .93); counts ranged from 60 for a 45-mm-FL female to 772 for one 90-mm FL. The oldest of eight fish, aged by the opercle method, was a 90-mm-FL, 4+-year-old female. Adults are omnivorous but tended toward carnivory; 75% of matter by volume consumed was invertebrates and 25% plants and detritus. Fish size was generally commensurate with flow, the largest fish occurring in the greatest flow. Adults were near bottom, in focal velocities ranging from 0 to 55 cm/s. Juveniles occupied a narrower range of depths and velocities than adults, and larvae occupied slack water. From December 1984 to September 1987, the total adult population ranged from 2600 to 2800. Although these numbers are higher than previously believed for Moapa dace, they are still sufficiently low to warrant its endangered status. The dependency of Moapa dace's different life history stages to various areas and habitat types of the Warm Springs area suggests that all remaining habitat is necessary for their survival.     

Opportunistic feeding in Sceloporus horridus from Jalisco, Mexico

Based on a sample of 17 adult specimens of Sceloporus horridus taken near Autlan, Jalisco, Mexico in May 1974 just before and just after the first rainfall of the year, we present the first published data on the food habits of this lizard. Important prey item taxa were Homoptera, Coleoptera, Hymenoptera, Orthoptera, and Isoptera. The absence of Homoptera and Orthoptera, and the concomitant greater relative importance of Isoptera and Hymenoptera in the diet after the rain than before indicates opportunistic feeding by S. horridus. Our data suggest that reproduction in this lizard is probably initiated soon after the first rains in late spring.