摘要:

Variation in the results of five near-identical bioassays of fathead minnows subjected to instant increase in water temperature is examined. It is shown that median tolerance limits for an instant temperature increase can be estimated with precision, and levels of stress tolerable to more than 50% of the test fish can be estimated with somewhat lower precision. It is suggested that the standard deviation of the population tolerance frequency distribution can be of practical value in evaluating the effect of dilution on lethality of wastes. It is concluded that TL50 values should indeed be used in calculations of “safe” levels of water quality alteration when bioassays and so called “application factors” are employed in regulating disposal of lethal agents.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1972)101<403:VIROIB>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1972

数据来源: Taylor

摘要:

Fish collections were made at nine stations along the Moapa River of southern Nevada. Four native species are ecologically separated into headwater and middle-stream types. The headwater fishes are ecologically segregated into one pond species (Crenichthys baileyi) and one stream species (Moapa coriacea). The apparent temperature preference for both species is near 29.5 C. Temperature range for Crenichthys is 27–32 C and for Moapa 19.5–32 C. Both Gila robusta and Rhinichthys osculus are most abundant in the turbid middle portion of the stream in undisturbed, deep riffle habitats. A fifth native species, Plagopterus argentissimus, is extremely rare or of accidental occurrence.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1972)101<408:EDOFOM>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1972

数据来源: Taylor

摘要:

Bluegills (Lepomis macrochirus Rafinesque) and largemouth bass (Micropterus salmoides Lacepede) were exposed to two applications of Dursban(R), an organophosphorus insecticide, at the recommended rates for mosquito control of 0.05 or 0.01 lb of active ingredient/A in experimental 0.1 acre ponds. Residues of Dursban in water 1 day after the applications ranged from 2.39 parts per billion (ppb) in the highest treatment to 0.97 ppb in the low treatment. Cumulative mortality in the untreated ponds during 63 days of observation was approximately 1% of the total population of each species of fish. Cumulative mortality of fishes during the same period in ponds treated at 0.01 lb/A was 3% for bluegills and 10% for bass, whereas the corresponding mortalities for the high application rate (0.05 lb/A) were 55% for bluegills and 46% for bass. Uptake of Dursban by fishes produced maximum residue values of 3.82 parts per million (ppm) in bluegills and 2.55 ppm in bass within 1 to 3 days after application of the insecticide at 0.05 lb/A. These residues decreased greatly within 2 weeks to less than 0.4 ppm and were undetectable after 4 weeks. Both species of fish taken from the ponds treated at 0.05 lb/A exhibited more than 80% inhibition of brain acetylcholinesterase activity as compared to fish from untreated ponds; fishes from these ponds had not recovered normal acetylcholin-esterase activity 28 days after application of the insecticide. Histological examination of tissues from bluegills and largemouth bass exposed to Dursban did not show conclusive evidence for pesticide-induced pathology. The high treatment reduced the total number of insects colonizing plate samplers by three-fourths, eliminated caddisflies, and severely reduced mayfly populations. We believe that the results of this investigation confirm the inadvisability, as suggested on product labels, of using Dursban at the current recommended rates of application for mosquito control in habitats where valuable fishery resources are to be protected.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1972)101<420:TOTIDR>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1972

数据来源: Taylor

摘要:

The gonads of 4,405 premigratory smolts from eight year classes of chinook salmon, Oncorhynchus tshawytscha (Walbaum), were inspected to determine sex. Nearly half of the smolts of seven of the year classes had been irradiated for their first 80 days of life by exposure to the gamma rays of cobalt-60 at rates that increased almost exponentially from 0.5 R/day the first year to a maximum of 50 R/day the last year. Sex ratios were unaffected by 5 R/day or less, but at 10 or more R/day gonadal development was retarded.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1972)101<428:SRAROG>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1972

数据来源: Taylor

摘要:

Bluegills were exposed to a temperature-zinc interaction consisting of five temperature regimes and four concentrations of zinc which were 1.0, 5.6, 10.0 and 32.0 mg Zn++/1. All of the above concentrations of zinc and a control were tested on five groups of fish which had been acclimated to (1) 20 ± 1 C, (2) 30 ± 1 C and fish which had been acclimated to 20 ± 1 C and were exposed to temperature increases at the following rates: (3) 1 C/24 hours, (4) 1 C/1 hour and (5) 1.5 C/10 minutes until a maximum of 30 C was reached.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1972)101<435:MCOBLM>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1972

数据来源: Taylor

摘要:

Annual distribution and abundance of young-of-the-year striped bass were measured from 1959 to 1970 in the Sacramento-San Joaquin estuary. Annual abundance of young bass in late summer was closely related to the amount of river flow in June-July into the estuary (r = 0.89). Highly significant correlations existed between striped bass abundance and salinity and water diverted from the estuary, both of which were mutually related to the amount of river flow. Six mechanisms which may control these relationships are discussed. Annual striped bass distribution in the estuary was also related to river flow (r = -0.93) and salinity (r = 0.88) with bass being farther upstream in years of low runoff and high salinity.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1972)101<442:DAAOYS>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1972

数据来源: Taylor

摘要:

To observe striped bass, Morone saxatilis (Walbaum), migration through the Chesapeake and Delaware Canal, we placed ultrasonic transmitters in the stomachs of five adult bass and traced their movements for as long as 4 days and nights in the spring of 1971. Three bass were prespawning and 2 postspawning. The tags were Smith-Root SR-69B; the receiving equipment consisted of an SR-70H hydrophone and a TA-60 sonic receiver. Tagged bass ranged from 470 to 908 mm in fork length. We experienced no shedding of tags, nor difficulty with sound transmission and reception. No bass tracked was travelling at all times; on the contrary, there were long rest periods between moves during both day and night. Fish were more active during the night than during the day. Prespawning adults tended to be moving more constantly than postspawning fish which tended to linger more within the canal. Lost signal could be picked up again fairly easily. One tagged fish was refound after a 24-hour interval.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1972)101<453:STSBIT>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1972

数据来源: Taylor

摘要:

Between 1952 and 1961 standing crops of brook (Salvelinus fontinalis), rainbow (Salmo gairdneri), and brown (Salmo trutta) trout were determined in August for a 5.7 mile section of Sagehen Creek in east-central California. In 1953 a creel census was initiated which continued through 1961. The purpose of the study was to determine if a moderately productive wild trout stream could support a substantial angler harvest over an extended period without augmentation with hatchery-reared trout.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1972)101<463:AAHOTI>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1972

数据来源: Taylor

摘要:

Effects of winter and spring floods on rainbow (Salmo gairdneri) and brook (Salvelinus fontinalis) trout were evaluated over a 10-year period in Sagehen Creek, California. Winter floods decimated developing eggs of fall-spawning brook trout. Because of reduced competition by young brook trout, survival of spring-spawned rainbow fry increased in years following winter floods. Conversely, spring floods destroyed rainbow eggs, thereby enhancing survival of young brook trout. Floods changed the species composition markedly and these changes endured for several years. Adult trout were adversely affected by the worst flood studied, but were unaffected by other floods of lesser magnitude. Effects of floods were not nearly as pronounced or predictable on adult trout as they were on young trout.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1972)101<478:EOFOTI>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1972

数据来源: Taylor

摘要:

Gonadal development, time of spawning, and fecundity of black bullheads were examined in 1969 and 1970 for insight into the reproductive potential of this species in a warm-water lake.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1972)101<483:RPOTBB>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1972

数据来源: Taylor