摘要:

The ability and persistence of salmonids in ascending pool-and-overfall fishways was measured in experimental “endless” fishway structures in which fishways of any height could be simulated. Six chinook salmon (Oncorhynchus tshawytscha), four sockeye salmon (O. nerka), and four steelhead trout (Salmo gairdneri) were permitted to ascend 1,000 feet in the experimental fishways. One sockeye salmon was allowed to ascend an endless fishway for over 5 days, climbing 6,648 feet, a vertical ascent of more than a mile, before the test was discontinued. Rate of ascent of all fish tested increased following an initial period of experience in the fishway. The level of blood lactate in the exercised fish showed no evidence of fatigue. Practical significance of the data in relation to fishway design is discussed.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1962)91[1:AOSTAH]2.0.CO;2

出版商:Taylor & Francis Group    

年代:1962

数据来源: Taylor

摘要:

Several experiments were run on hatchery ponds to determine the effects on pond metabolism of leaving cut but untreated aquatic vegetation and the effects of treating mats of cut vegetation with 2, 4-D and ammonium nitrate. Cutting vegetation did not improve environmental conditions until cut plants decayed. Ammonium nitrate appeared to be superior to 2, 4-D for inducing decay. When mats were treated with ammonium nitrate, blooms of zooplankton were produced which persisted up to 8 months. No phytoplankton blooms developed after ammonium nitrate treatment, and the higher aquatic vegetation did not grow faster in the treated ponds. Fish kills were not observed near the untreated mats, but dissolved-oxygen conditions there were unfavorable. No fish kills were observed after ammonium nitrate treatment, and growth rates of fish in treated ponds were good.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1962)91[8:EOCAVA]2.0.CO;2

出版商:Taylor & Francis Group    

年代:1962

数据来源: Taylor

摘要:

The fate of toxaphene, applied in three treatments at a total calculated concentration of 0.05 p.p.m. to Clayton Lake, New Mexico, was followed over a 1.5-year period. A detailed description of the chromatographic method of analysis is given. Water concentrations of toxaphene were higher in leeshore samples than in windward samples for 2 weeks after the application; toxaphene levels then appeared to reach a constant value of about 0.001 p.p.m. for at least an additional 250 days. Total body concentrations of toxaphene were determined in trout and bullheads present in the lake during the poisoning and in trout placed in the lake in live-cars subsequently. Trout were more susceptible to toxaphene and accumulated lower body levels than bullheads. Bullheads which showed symptoms of toxaphene poisoning when collected had higher levels than did normal-appearing individuals. No difference in levels was observed in live-car trout collected dead as compared to survivors. Aquatic vegetation accumulated high concentrations of toxaphene; low concentrations were found in some sediment samples. The significance of these findings is discussed.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1962)91[14:DADOTI]2.0.CO;2

出版商:Taylor & Francis Group    

年代:1962

数据来源: Taylor

摘要:

Sexual maturity and fecundity of largemouth bass (Micropterus salmoides) were studied in Maine. Ovaries and ovarian constituents of 46 female bass are described. Atresia, although present, is not prevalent in mature ovaries. Size-frequency distribution of ova was used to determine ovary maturity. Ovum production per fish of 20 mature bass was determined by a dry-weight method. Individual fecundity ranges from 5,000 to 82,000 ova and varies considerably with the age and size of the fish. Ovum production appears to decline in fish older than 7 years. Regression equations are given describing the relationships between fecundity and age, weight and length. The correlation between fecundity and age is higher than between fecundity and weight or fecundity and length. Weight is more closely correlated to fecundity than is length. Regression equations are graphically illustrated and their use for prediction purposes is shown.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1962)91[23:SMAFOT]2.0.CO;2

出版商:Taylor & Francis Group    

年代:1962

数据来源: Taylor

摘要:

Early life history of largemouth bass (Micropterus salmoides) at Lake George and adjoining sloughs, Anoka County, Minnesota, is described. Bass spawning first occurred 2-5 days after mean daily water temperature exceeded 60° F. Two hundred and sixty-six nests were found on needlerush, waterlily roots, humps of fibrous material, aquatic vegetation, and sand in 10 to 62 inches of water. Egg survival at time of hatching varied from 0 to 94 percent. Percentage of successful nests from a single spawning period varied from 0 to 100. Number of fingerlings per brood 2 weeks after rising from the nest varied from 500 to 12,715 fish with mean brood size of 5,600 in 1956 and 1957 and 3,600 in 1958. Analyses of bag-seine catches showed 1.0, 5.5, 10.0, and 1.3 fingerlings per 1,000 square feet in 1955, 1956, 1957, and 1958, respectively. Number of yearlings in the four year classes at the beginning of the second summer of life were 0.05, 0.42, 0.93, and <0.05 per 1,000 square feet. Year classes were weak in 1955 and 1958 and strong in 1956 and 1957. Year-class strength was set after egg deposition and before fingerlings were 2 weeks old. Water temperature was directly related to egg survival and nest success. Wind was the most important single factor in year-class formation in Lake George. Egg survival was highest on needlerush and lowest on sand. Two-thirds of all successful nests were in water deeper than the median depth. Illumination, dissolved oxygen, total alkalinity, hydrogen-ion concentration, cannibalism, predation, food habits, growth rate, and condition were not factors in determining year-class strength.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1962)91[29:FOYCIL]2.0.CO;2

出版商:Taylor & Francis Group    

年代:1962

数据来源: Taylor

摘要:

Sport-fishing catch from Gladstone Lake, a 481-acre hard-water bass-panfish lake in north-central Minnesota, averaged 24.3 pounds (about 65 fish) per acre over a 7-year period (1952-58). Of the weight of fish taken 25.4 percent was larger predaceous fishes, including 13.4 percent (3.2 pounds per acre) of largemouth bass (Micropterus salmoides). Panfishes, especially bluegill (Lepomis macrochirus), made up the bulk of the catch. Average summer fishing pressure over the 6 years was 37 hours per acre and of the same magnitude as that for other bass-panfish lakes in this area. The fish population was sampled by seining in 1957 and 1958 and size of the bass population estimated by marking and recovery methods. In 1957 there were estimated to be 11,000 bass 6 inches or longer (23 per acre); in 1958, 5,500 (12 per acre). Approximately 50 percent of this decline was attributed to poor recruitment from the 1955 year class. The exploitation rate was 14.6 percent in 1957 3.5 bass per acre) and 15.6 percent in 1958 (1.8 per acre). Total fishing pressure was 29.9 hours per acre in 1957 and 27.3 in 1958. Fishing mortality of age-IV and older bass was 15 percent during the 2 years, and estimated natural mortality, 47. Age-groups IV and younger were taken incidentally to panfish angling. Larger bass were caught mostly by anglers fishing specifically for them. During the 2 years 30 percent of the total fishing pressure was directed at largemouth bass and 50 percent at panfishes. Catch of the smaller bass appears to be related to the goodness of panfish fishing. The population of larger bass declined 30 percent from 1957 to 1958, but the catch declined 48 percent and fishing pressure for larger fish declined 55 percent. The catch of smaller bass declined 35 percent and the population declined about 55 percent. Age-groups V-VIII (1 to 3 pounds) were taken in both years in greater proportion to their numbers than ages IX and older (3.5 to 5.0 pounds). Angling habits and success of panfish anglers had considerable influence on the bass catch. Opening the bass season 2 weeks earlier in 1957 and 1958 than in the 5 preceding years had little influence on the catch and about half the fish were taken during the first month in both instances.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1962)91[42:LBPAHG]2.0.CO;2

出版商:Taylor & Francis Group    

年代:1962

数据来源: Taylor

摘要:

Estimates of population density of all species of fish except the slimy sculpin were made in selected areas of three hard-water streams and three soft-water streams in Pennsylvania. Total standing crops ranged from 46 to 354 pounds per acre. Brown trout (Salmo trutta) stocks ranged from 13 to 137 pounds per acre. Average annual survival of brown trout ranged from 0.189 to 0.554. Recruitment appeared to be fairly stable except for occasional variations believed caused by flood or drought conditions. Growth rate of brown trout was significantly correlated with specific conductance of the water. The data suggest also that a relationship may exist between specific conductivity and standing crop of fish expressed in pounds per acre.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1962)91[53:AECOSP]2.0.CO;2

出版商:Taylor & Francis Group    

年代:1962

数据来源: Taylor

摘要:

Spawn taken annually from rainbow trout (Salmo gairdneri) entering the inlet at Lake DeSmet constitutes Wyoming's primary source of trout eggs. The number of eggs taken has fluctuated between 500,000 and 4 million. Effects of planting rainbow trout of spring- and fall-spawning races and locations of plants were studied from marked fish. Rainbow trout of the spring-spawning race entered the spawning run in an 11-to-1 ratio over the fall-spawning strain. Fish planted in the inlet ditch returned in a 3-to-1 ratio over those planted in the far end of the lake. Anglers harvested marked trout randomly from all portions of the lake. Trout apparently migrated to the spawning trap from all portions of the lake. Ten percent of the adult trout shore-trapped and tagged in the spring migrated to the inlet ditch and spawning trap. Seventeen percent of females trapped in 1957 returned in 1958 to make up 13 percent of the female run. Most of the run is spawning for the first time. Creel census from January to June during 1958, 1959, and 1960 indicated harvest of trout was not large enough to affect the spawning run seriously. Between two and four trout per surface acre were harvested. Planted trout must be at least 4 inches long (40 per pound) to escape predation by yellow perch. An annual plant of 500,000 spring spawning trout appears sufficient to maintain the rainbow trout population. At least 40,000 of these fish should be planted in the inlet ditch to insure an annual take of 2 million eggs.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1962)91[63:EOHMAS]2.0.CO;2

出版商:Taylor & Francis Group    

年代:1962

数据来源: Taylor

摘要:

Mixing depth and turbidity negatively affect the productivity of an aquatic environment through the control they exert on the effective energy available for photosynthesis. A feedback equation is developed that defines the interaction of these two quantities with the production by phytoplankton. The equation permits calculation of the relative productivity of any body of water provided nutrients are assumed adequate, and provided depth of mixing and turbidity are known. Calculated relative production corresponded very well with observed production for a series of 33 small shallow ponds. The possibility is advanced that the same principles apply to reservoirs when thermocline depth can be regarded as mixing depth, and further, it is suggested that the productivity of reservoirs might be increased by reducing the depth of the mixed layer by withdrawing from the surface. In addition, this practice might further enhance production by mixing deeper water, richer in nutrients, into the euphotic zone during the productive season.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1962)91[69:EOMDAT]2.0.CO;2

出版商:Taylor & Francis Group    

年代:1962

数据来源: Taylor

摘要:

Coastal cutthroat trout (Salmo clarki clarki Richardson) were studied at Sand Creek, Tillamook County, Oregon (1946-49). Upstream runs occurred mainly in fall and early winter months and downstream runs in the spring. Upstream migrant sea-run cutthroats averaged 13.6 inches, while upstream non-sea-run trout averaged 6.0 inches, fork length. Downstream trout, mainly initial migrants, averaged 5.7 inches long. Of summer-resident trout, 8.7 percent were of legal angling length. Scales of sea-run trout gave ages of 2-10 years, with different combinations of stream and sea life. Most sea-run trout spawned after one season in the sea and a third had spawned one to three times. Growth was back-calculated from scale readings. Survival figures are given.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1962)91[77:MAGOTC]2.0.CO;2

出版商:Taylor & Francis Group    

年代:1962

数据来源: Taylor