摘要:

Mean standing crop of 5 brood years of age 0+ salmon prior to regulation of stream flows was estimated for each kg of female spawners/ha. Estimate was 20.1 fish/ha weighing 0.035 kg. Mean standing crop of 5 brood years of age 0+ salmon for each kg of female spawners following flow regulation was 39.0 fish/ha weighing 0.088 kg. The estimates are not significantly different at the 95% confidence level but are at the 70% confidence level. Mean standing crop of 5 brood years of 10–15 cm age I+ salmon prior to regulation of stream flows was estimated for each age 0+ salmon/ha and for each kg of age 0+ salmon/ha of the same brood years. So measured each age 0+ salmon produced 0.0040 kg of age I+ salmon and each kg of age 0+ salmon produced 1.876 kg of age I+ salmon. For 4 brood years of 10–15 cm age I+ salmon following flow regulation each age 0+ salmon produced 0.0029 kg of age I+ salmon and each kg of age 0+ salmon produced 1.115 kg of age I+ salmon. Differences for before and after flow regulation are not significant at the 95% confidence level. Mean annual survival from age 0+ to 10–15 cm age I+ salmon prior to and following flow regulation was 18.69% and 19.61% respectively. The differences in survival are not significant at the 95% confidence level. Prior to water control, mean annual number of all fish except salmon was 3,775/ha while mean annual weight was 19.003 kg/ha. After water regulation mean annual number of all fish except salmon was 6,795/ha while mean annual weight was 21.504 kg/ha. Neither number nor weight differences are different at the 95% confidence level. Small fish tended to respond to the increased flows more than the larger fish. Some practical aspects of operation of small water control dams are discussed particularly the desirability of releasing additional water following large rains in dry seasons.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1974)103<1:EORFOS>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

Migration of newly planted yearling coho salmon (Oncorhynchus kisutch) out of a Lake Michigan tributary and through the connecting bay was monitored with trap nets and pound nets in April-June 1968 and 1969. Concurrently, food habits of coho and their potential piscine predators were examined. Yearling coho migrated out of the Whitefish River within 2 wk and through northern Little Bay de Noc within 4 wk. They fed primarily on insects and crustaceans in both river and bay. Coho were eaten by only 2 of 221 predatory fishes examined. Thus, yearling coho did not prey upon or compete significantly with native game fishes for food, nor were they utilized as food extensively by resident fishes.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1974)103<10:MFHAPO>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

Species of forage fish in stomachs of walleye and their abundance in trawl catches were compared in 1968–71. Young yellow perch were the predominant species in trawls and were consistently selected by walleyes. Consumption of young white perch and walleyes by older walleyes increased during periods of low yellow perch abundance which suggested that young yellow perch might act as a buffer controlling intensity of predation. This possibility was assessed by comparison of relative survival of white perch and walleye cohorts between the first and second year of life with indices of yellow perch density between 1959 and 1970. Close correlations between these variables support the conclusion that abundance of young perch governs intensity of predation on other forage size fish and indirectly controls the size of the walleye population by regulating cannibalism.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1974)103<15:IBYPAW>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

Food habits of young and yearling white bass, Morone chrysops, were determined on the basis of seven sets of samples taken at approximate 2-hr intervals from sunset to sunrise in midsummer and early autumn of 1966 and 1967. Digestion rate studies were carried out in situ and in the laboratory. In most cases young and yearling fish evacuated a major share of their stomach contents within 7 to 8 hr after termination of feeding. Laboratory and field data suggest that the major feeding activity of both age groups occurred prior to sunset; young fish apparently ceased feeding at 2 to 3 hr post-sunset while yearlings continued to feed at low levels throughout the night. Both age groups fed heavily on Daphnia spp. and Leptodora kindtii, but yearlings also showed heavy dependence on macroinvertebrates (Amphipoda, Diptera and Odonata) and fish (principally Centrarchidae and Cyprinidae) in later post-sunset hours.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1974)103<25:FHOYAY>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

Energy budgets, based on laboratory and field studies in 1967 and 1968, were constructed for young-of-the-year white bass Morone chrysops. Major food items in the diet of the fish were cladocerans, copepods, amphipods, insect larvae and pupae. Estimates of daily food intake were based on two periods of intense feeding (early morning and late afternoon). Fish egested 39% of the food consumed during a single feeding period. Mean caloric content of this material was 3,339 and 3,760 g˙cal/g dry weight for laboratory and field samples, respectively.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1974)103<32:ETBYWB>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

A respirometer was utilized to determine the energy cost of food utilization in the bluegill Lepomis macrochirus. Prior to the study, fish were acclimated to the experimental photoperiod (16 hr light) and temperature (15, 20 and 25 C) for 90 and 14 days, respectively. Each fish was tested in the respirometer for 3-day periods. After an initial acclimation period of 24 hr, metabolic rates were determined at 2-hr intervals for the next 48 hr and were converted to their caloric equivalents. Fish were fed to satiation on mayfly nymphs (Hexagenia limbata) in the morning and evening of day 3. We calculated the energy cost of food utilization by determining the increase in energy of respiration subsequent to feeding.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1974)103<38:ECOFUI>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

Abundance and growth data indicated a 2-yr life cycle for longfin smelt with even-numbered year-classes being more abundant and showing a lower growth rate than the odd. The Cedar River was the major spawning area. The peak of the spawning run occurred during mid-March in 1970 and mid-February in 1971. The average size of spawning adults decreased as the spawning runs progressed. Males were consistently larger than females and dominated in numbers throughout the runs by a 3:2 ratio. The time of the spawning migration was related to body size; the larger adults of the odd year-class spawn earlier in the year than the smaller adults of the even year-class.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1974)103<46:AGASOT>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

Channel catfish, Ictalurus punctatus (Rafinesque), from Lake Sharpe, a 22,600-ha reservoir on the Missouri River in South Dakota, showed little change in abundance during the first 8 yr of impoundment, 1964–1971. All year classes from 1953 through 1969 were represented in gill net catches. Mean lengths of fish at a given age averaged 20% less in 1971 than in 1964. Average annual survival rate was calculated to be 69% from age VI to XVI. Some females attained sexual maturity at age VII, but only 50% were mature at age XIV. Less than 10% of the females 437 to 489 mm total length were mature; all females over 593 mm were mature.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1974)103<53:AGSAMO>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

A self-sustaining rainbow trout population has developed in the North Platte River drainage. This population inhabits McConaughy Reservoir and reproduces successfully in tributary streams of the North Platte River located approximately 113 to 145 km above the reservoir. Fall and spring spawning populations migrate from the reservoir.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1974)103<59:SRTSGP>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

Breeding male fathead minnows (Pimephales promelas) develop a dorsal pad as well as several other secondary sexual characteristics. The dorsal pad consists of a dermal layer made up of loose connective tissue which develops above the scales, and an epidermal layer of stratified epithelium. The outer layer of the epidermis contains many mucus cells. Mucus secreted by this layer is deposited on the spawning surface during contact movements performed by breeding males. Taste buds are present in the epidermal layer of the dorsal pad and other regions. Contact movements by breeding males may facilitate chemosensory sampling of the spawning site and eggs.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1974)103<65:FMOTDP>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor