Some relationships between water fertility and egg production in brown trout ( Salmo trutta ) from Montana streams

Relationships between water fertility (as measured by conductivity and alkalinity) of 17 Montana streams and the attainment of sexual maturity and fecundity of their resident female brown trout were studied. Fish from the streams having conductivity and alkalinity levels greater than 100 micromhos / cm and ppm CaCO 3 , respectively, were younger at sexual maturity than fish from waters with lower levels. The attainment of earlier sexual maturity in fish from the former streams could not be completely explained on the basis of greater growth rates. Fish from the stream having the highest levels of conductivity had the slowest growth rate but became sexually mature at the youngest age. A positive relationship was found between chemical fertility of streams and the fecundity of their fish. However, in the stream having the highest levels of conductivity, fish were the least fecund. It was concluded that the chemical fertility of these streams is generally related to the age at sexual maturity and fecundity of fish.       

Some parasites of paddlefish ( Polyodon spathula ) from the Yellowstone River, Montana

One species of copepod ( Ergasilus elongatus ), one trematode ( Diclybothrium hamulatum ), two nematodes ( Camallanus oxycephalus and Contracaecum sp.), and two cestodes ( Marsipometra hastata and M. parva ) were recovered from 17 paddlefish ( Polyodon spathula ) collected from the Yellowstone River, Montana, on 11 and 18 May 1973. The male paddlefish averaged 69.4 nematodes and 157.6 cestodes per infected fish while the females averaged 12.0 nematodes and 415.7 cestodes. The higher intensity of cestode infection in female paddlefish was attributed to their larger size and consequent greater intake of food resulting in more exposure to the cestode intermediate hosts ( Cyclops bicuspidatus ).     

Growth and reproduction of the flannelmouth sucker, Catostomus latipinnis, in the Upper Colorado River Basin, 1975-76

Growth rates estimated using the scale annuli of flannelmouth sucker, Catostomus latipinnis , did not differ between fish collected from the Gunnison and Colorado rivers, and the Green and Yampa rivers. However, body condition and fecundity were significantly greater in the former population. Age of first maturity for male and female fish from all rivers was IV; and most fish were mature by age VII. The smallest mature female collected was 405 mm, and the smallest mature male was 391 mm total length. Fecundity ranged from 4,000 ova in fish 450 mm long to 40,000 ova in a 500-mm fish: mean ovum diameter was 2.39 mm. Ripe male flannelmouth suckers were collected from early April through June; ripe females were collected from both study areas during May and early June.         

Host-parasite studies of Trichophrya infesting cutthroat trout ( Salmo clarki ) and longnose suckers ( Catostomus catostomus ) from Yellowstone Lake, Wyoming

Trichophrya sp. (Protozoa) on the gills of cutthroat trout ( Salmo clarki ) and longnose suckers ( Catostomus catostomus ) was studied using light and electron microscopy and tracer techniques. All cutthroat trout, 14 cm in total length and above, from Yellowstone Lake, Yellowstone National Park, Wyoming, were infested with the suctorian. No trichophryans were found on fry or fingerling cutthroat trout. Sixty percent of the examined longnose suckers from the same location were infested. Light microscopy disclosed extensive pathology of gill epithelium in longnose suckers infested with Trichophrya that was not observed for infested cutthroat trout. Electron micrographs show damage to immediate host gill cells by both parasites, depicted by a reduction and lack of mitochondria. Both parasites form attachment helices (0.52 × 0.04 μ m), which may originate in the protozoan cell membrane and function for maintenance of parasite position on the host cell. There was no uptake of 14 C, injected into host fish, via the attachment helices by the parasite that further substantiated the mechanical function for the spiral structure. Protozoan feeding on host tissue may be accomplished by use of necrotic gill tissue and mucus.        

Aspects of the biology of the flathead chub ( Hybopsis gracilis ) in Montana

Mature flathead chubs ( Hybopsis gracilis ) were present in mid - July and mid - August collections from the Musselshell River, Montana. The estimated numbers of mature eggs present in eight females were 360–753 per female. The smallest mature female and male collected were 113 and 123 mm in total length, respectively. The male to female sex ratio in collections was about 1:1. Only small differences were detected among the length – weight relationships of males and females and samples taken from various seasons and localities in Montana. Observations on size groups, fish associates, and habitat characteristics of flathead chubs are presented.         

Parasites of the cutthroat trout, Salmo clarki, and longnose suckers, Catostomus catostomus, from Yellowstone Lake, Wyoming

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;} Twenty-five cutthroat trout ( Salmo clarki ) and eight longnose suckers ( Catostomus catostomus ) from Yellowstone Lake, Wyoming, were collected and examined for parasites in 1985. Cutthroat trout had at least six different species of parasites that included both protozoans and helminths. The greatest number of parasite species on one fish was nine. Parasites added to the known list for cutthroat trout from Yellowstone Lake, Wyoming, were: Myxosoma sp., Diphyllobothrium ditremum, Diphyllobothrium dendriticum, Diplostomum baeri, and Posthodiplostomum minimum. These data were compared with a previous survey (1971) and a checklist of parasites of cutthroat trout in North America. There are 17 species of parasites and two fungal species reported for cutthroat trout from Yellowstone Lake. Trichophrya catostomi, Diplostomum spathaceum, and Ligula sp. were observed in the small sample of longnose suckers.        

Electrophoretic study of cutthroat trout populations in Utah

Thirty - nine Utah streams were sampled for cutthroat trout. Of these, 31 contain cutthroat or cutthroat / rainbow hybrid populations. By using starch gel electrophoresis, these populations were segregated into three groups. One group consisted predominately of fish from the Sevier River (of the Bonneville Basin) and Colorado drainages. A second was primarily populations from the Bear River Drainage (Bonneville Basin) as well as some scattered populations along the Wasatch Front (Bonneville Basin). The third consisted of Wasatch Front populations and populations that have hybridized with rainbow trout. Since different subspecies of cutthroat trout are native to the Colorado and Bonneville drainages, one would expect the populations from within the Bonneville Basin to be more similar to one another and less similar to the Colorado River populations. That this did not occur raises questions concerning the evolutionary relationships of the subspecies and the populations. It is clear that at least a northern (Bear River) and southern (Sevier River) form of the Bonneville cutthroat exists. The Wasatch Front may represent an intermediate zone where these two forms intergrade.         

Size selection of food by cutthroat trout, Salmo clarki, in an Idaho stream

The mean size of food and amount of food consumed by cutthroat trout from Palisades Creek in southeastern Idaho increased with trout length. Number of organisms of terrestrial origin, number of aquatic larvae, number of ants, and number of berries from redstem dogwood were related to trout length. The size range and number of taxa consumed increased with trout size, indicating that as trout get larger, they broaden their feeding menu. The minimum size of food consumed was relatively constant for all trout, but larger trout appeared to feed more from the stream bottom. Trout may have a minimum length of food, below which items cannot be detected as food. Other possible factors affecting the feeding of cutthroat trout are mentioned.         

Helminth parasites of the white-tailed jackrabbit, Lepus townsendi, from northwestern Colorado and southern Wyoming

Helminth parasites of white - tailed jackrabbits, Lepus townsendi , were surveyed from southern Wyoming and northwestern Colorado. A total of eight helminth species were identified, including two species of adult cestodes, Mosgovoyia pectinata and M. varabilis ; three species of larval cestodes, Multiceps serialis , Taenia pisiformis , and Taenis sp. ; and three species of nematodes, Dermatoxys veliger , Passalurus ambiguus , and a filariid, Micipsella brevicauda . In addition, eggs of an unidentified species of Nematodirus were found in pooled fecal samples. The cysticercus larva of Taenia sp. is a species new to science and will be reported elsewhere. Mosgovoyia varabilis and Micipsella brevicauda are new records for the white - tailed jackrabbit.         

Life history of the Lahontan cutthroat trout, Salmo clarki henshawi, in Pyramid Lake, 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;} The Pyramid Lake Lahontan cutthroat trout ( Salmo clarki henshawi ) population was sampled on a monthly basis from November 1975 through December 1977. A subsample of 676 trout, stratified by fish size and lake habitat, provided biological data. The entire population is presently derived from hatchery production, stocked at lengths of approximately 75 to 300 mm. Peak annulus formation occurs in March and April, followed by the period of maximum growth. Scale patterns illustrate a variable growing season. Maximum growth in length is in the first three years of life; after that males begin to grow faster than females. Males attained a greater age in our sample; i.e., the oldest male was seven years old compared to six years for females. The Pyramid Lake Lahontan cutthroat trout exhibit nearly isometric growth. The legal sport fishery removed 380 mm); other decimating factors are poorly understood. No evidence of the following diseases or pathogens was found in the Pyramid Lake population, presuming a carrier incidence of 2 percent at the 95 percent confidence level: infectious pancreatic necrosis, infectious hematopoietic necrosis, viral hemorrhagic septicema, bacterial kidney disease, enteric redmouth, furunculosis, whirling disease, blood fluke; however, 7 of 235 (≈3 percent) adults sampled at the Marble Bluff fishway were positive for furunculosis. Small trout feed primarily on zooplankton and benthic invertebrates; cutthroat trout >300 mm are piscivorous, feeding almost exclusively on tui chub ( Gila bicolor ). The spawning migration of Pyramid Lake cutthroat trout to the Marble Bluff egg taking facility in spring 1976 and 1977 peaked in April and May. Females mature at three or four years (352–484 mm), and males mature at two or three years (299–445 mm). Mean diameter of mature eggs is 4.51 mm; both ovum size and fecundity are a function of fish size. Fecundity ranges from 1241 to 7963 eggs, with a mean of 3815. Lahontan cutthroat trout comprise     

The eye fluke disease (Diplostomatosis) in fishes from Utah

During 1976 and 1977, 798 fish representing 11 species from eight collection sites in Utah were examined for metacercariae of Diplostomum spathaceum, which causes the fish eye fluke disease, diplostomatosis.   Eight species were infected. The infection rate ranged from 7 percent of 46 Salmo gairdneri from Soldiers Creek Reservoir to 100 percent in 7 species of fish from four collection sites. Summary charts for four years of data are given for collection sites, piscine hosts in Utah, and fish hosts for Strawberry Reservoir, Utah.     

Incidence of the leech Helobdella stagnalis on the Colorado River in west central Colorado

Fifty-seven fish of three genera were taken from the Colorado River in west central Colorado and examined for external parasites. No external parasites were found on Ictalurus. Seven percent of the Hybognathus and 100 percent of the Catastomus were infected with a Hirudinean of the species Helobdella stagnalis.        

Biotic and abiotic factors related to redband trout occurrence and abundance in desert and montane streams

Redband trout Oncorhynchus mykiss gairdneri in the Columbia River Basin of western North America occupy desert and montane streams with variable habitat conditions. In general, desert streams are lower in gradient and elevation, contain less large substrate and more silt substrate, are less shaded by overhead vegetation, and have higher summer water temperature than montane streams. Consequently, we assessed whether the relationships between biotic and abiotic factors and the occurrence and abundance of redband trout in southwestern Idaho differed between desert and montane streams (<25 m mean width). Increased occurrence of redband trout in desert streams was most strongly related to increased stream shading and decreased amounts of silt substrate, followed by increased amounts of cobble/boulder substrate and absence of piscivorous fish (i.e., smallmouth bass Micropterus dolomieui and northern pikeminnow Ptychocheilus oregonensis ). In montane streams, increased occurrence of redband trout was most strongly related to decreased site elevation and increases in cobble/boulder substrate, followed by decreases in stream gradient and width. Furthermore, occurrence of redband trout decreased in desert streams at mean summer (June–August) water temperature (Temp smr ) >16 °C, whereas for montane streams, occurrence increased at Temp smr >9 °C. Redband trout density in desert streams was most strongly related to higher stream order (i.e., headwater streams), increased stream shading, and increased amounts of cobble/boulder substrate. In montane streams, redband trout density was not well explained by any stream conditions, but stream shading had the strongest positive relationship with density. Redband trout density was negatively related to Temp smr in desert streams, but the relationship was weak for montane streams. That environmental conditions related to the occurrence and abundance of redband trout differ between desert and montane streams is important for fisheries managers who manage these disparate populations occurring in such close proximity to each other.     

The scotopic visual sensitivity of four species of trout: a comparative study

We compared the maximum scotopic visual sensitivity of 4 species of trout from twilight (mesotopic) to fully dark-adapted vision. Scotopic vision is the minimum number of photons to which a fully dark-adapted animal will show a behavioral response. A comparison of visual sensitivity under controlled laboratory conditions showed that brown trout ( Salmo trutta ) and brook trout ( Salvelinus fontinalis ) had maximum scotopic thresholds (1.1 × 10 –4 μmol ? m –2 s –1 , ～0.005 lux) 2 times lower than rainbow trout ( Oncorhyncus mykiss ) and Snake River cutthroat trout ( Oncorhynchus clarki bouvieri ), which did not differ from each other (2.1 × 10 –4 μmol ? m –2 s –1 , ～0.01 lux). A literature review tended to corroborate these results in that brown trout and brook trout were reported to be more active during the night and at twilight than cutthroat trout and rainbow trout. We also measured light intensity within open versus shaded reaches during the day, dusk, and night in 3 Rocky Mountain streams. The scotopic sensitivity of brown trout and brook trout was sufficient to allow foraging during all twilight periods and under average nighttime light intensities in open and shaded reaches, whereas the scotopic sensitivity of rainbow trout and cutthroat trout may restrict their foraging to relatively bright nocturnal conditions (twilight or a moonlit night). Native cutthroat trout restoration efforts may have greater success in open versus shaded stream reaches in the Rocky Mountains and elsewhere.     

Metazoan parasite fauna of the round goby Neogobius melanostomus Pallas, 1811 (Perciformes: Gobiidae) collected from the Black Sea coast at Sinop,Turkey

Round gobies (Neogobius melanostomus) were collected from a small stream connected to the Black Sea coast of Sinop, Turkey and examined for metazoan parasites. A total of 122 gobies was investigated throughout a 1‐year period. Long‐term investigations can be useful for finding rare parasites and for determining the diversity and seasonality of parasites. Parasite species recovered were a Digenea gen. sp., Pygidiopsis genata, Ascocotyle sp., Gyrodactylus proterorhini, Dichelyne minutus, Hysterothylacium aduncum, Spiroxys sp., Neoechinohynchus rutilii, and Ergasilus sieboldi. Overall infection prevalence (%) and mean intensity values were 97.5% and 78.2±23.1 parasites per infected fish, respectively. Infection prevalence and mean intensity values for each parasite species in relation to season, fish size, and sex were also determined and discussed.     

Contrasting movement and activity of large brown trout and rainbow trout in Silver Creek, Idaho

Recent radiotelemetry studies demonstrated that stream-dwelling trout are mobile, but few have compared sympatric species. We used radiotelemetry to simultaneously monitor positions of 20 brown trout and 21 rainbow trout from May or June 1994 to February 1995 in Silver Creek, a small spring-fed stream in south central Idaho. Our biweekly observations from May to September indicated that rainbow trout had larger home ranges (medians, 606 m v. 131 m) and moved greater distances (medians, 1109 m v. 208 m) than brown trout. Furthermore, rainbow trout used more positions than brown trout (means, 7 v. 3) over this interval. Hourly diel monitoring revealed no significant difference in 24-h home ranges of rainbow trout and brown trout (means, 77 m v. 105 m). However, activity patterns of the 2 species differed; rainbow trout activity was usually highest during the day, whereas brown trout activity tended to peak at night. Differences in foraging strategies and response to disturbance may be responsible for differences in mobility.     

New Sclerocactus (Cactaceae) from Nevada

Described is Sclerocactus blainei Welsh & Thorne, sp. nov. from Nye County, Nevada.        

Diplostomiasis in native and introduced fishes from Yellowstone Lake, Wyoming

Totals of 101 native Yellowstone cutthroat ( Oncorhynchus clarki bouvieri ), 27 introduced lake trout ( Salvelinus namaycush ), and 40 introduced longnose sucker ( Catostomus catostomus ) from Yellowstone Lake, Wyoming, USA, were examined for eye flukes. Metacercariae of the trematode fluke Diplostomum were in vitreous humor and/or lens of 94% of Yellowstone cutthroat trout, 92% of lake trout, and 78% of longnose sucker. Longnose sucker had 7% prevalence of infection in both lens and vitreous humor of metacercariae, while Yellowstone cutthroat trout had 3% and lake trout 8%. Diplostomum spathaceum was in lens tissue of 5% of infected Yellowstone cutthroat trout and 93% of longnose sucker; Diplostomum baeri was in vitreous humor of 92% each of infected Yellowstone cutthroat trout and lake trout. Morphological characteristics indicate that a single species infected the lens of Yellowstone cutthroat trout and longnose sucker, while another species infected lake trout. Impacts of the parasite interchange between native and introduced fishes of Yellowstone Lake, Wyoming, are unknown but should be monitored each year.     

Effects of watershed alteration on the brook trout population of a small Black Hills stream

The impacts of adjacent landscaping activity and livestock presence on the brook trout ( Salvelinus fontinalis ) population of a small Black Hills stream were evaluated. Moderate changes in temperature, turbidity, and fecal coliform numbers did not influence brook trout densities. Stream morphometry, particularly factors affecting stream cover, appeared to have the greatest impact on numbers of trout. Brook trout were poor indicators of moderate changes in water quality, but they were adequate indicators of the physical perturbations within the stream.      

Different life histories of brook trout populations invading mid-elevation and high-elevation cutthroat trout streams in Colorado

Brook Trout ( Salvelinus fontinalis ), native to eastern North America, have invaded many montane cold-water systems of western North America, and these invasions are implicated in the decline of native cutthroat trout ( Oncorhynchus clarki ). If fisheries biologists are to be effective in managing brook trout invasions, demographic models that predict invasion success will need to incorporate life history variation in different environments. We tested whether brook trout populations invading streams at 2 different elevations varied in life history characteristics that influence population dynamics and potential invasion success. In the high-elevation stream (3195 m), water temperatures were colder and brook trout apparently grew more slowly (i.e., had shorter lengths-at-age), became sexually mature 2 years later, and had life spans 2 to 3 times longer than those in the mid-elevation stream (2683 m). This flexibility in life history may allow brook trout to maximize their chance of establishment and invasion success among elevations. We propose that in mid-elevation streams fast growth and early maturity maximize fitness and can lead to rapid establishment and high population growth rates. In high-elevation streams, slow growth, later maturity, and a long reproductive life span may allow brook trout to successfully establish populations in these marginal habitats where recruitment is often poor.