摘要:

The growth and age structure of mountain whitefish, Prosopium willlamsoni, was compared from three sample locations in the North Fork Clearwater River, and a tagging study initiated to assess movement and migratory behavior. No difference was detected in growth or age structure of whitefish in two streams of the upper drainage, and juveniles representing age groups I and II were generally absent from upper river populations. Age groups I and II whitefish from the lower North Fork Clearwater had significantly greater growth than similar fish from the upper river. The sample from the lower river contained whitefish as old as age IV, whereas fish to age XIV were found in the upper reaches.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1975)104<68:AGAMOM>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor

摘要:

Annual reproductive cycles of largemouth bass (Micropterus salmoides) collected in the heated area of a 1120-hectare reservoir receiving thermal effluent were similar to cycles from bass collected in unheated waters during 1969 and 1970. Average maximum monthly temperatures at the heated area exceeded those in unheated waters by greater than 10 C for the 2 years. Few monthly differences in gonosomatic indices were found between heated and unheated areas. Earlier attainment of maximum gonadal size and the presence of significantly larger juvenile bass at the heated area suggested that reproduction might be accelerated by thermal discharge. However, gonadal condition indicated that the reproductive period started in March and continued through April in both areas. Reproduction may have been advanced in some heated-area bass, although this was not obvious from overall changes in the reproductive cycles of bass from unheated areas.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1975)104<77:RCOLBM>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor

摘要:

The early life history of the smallmouth bass was studied for two summers (1971-1972) in South Branch Lake, Penobscot County, Maine, to determine what factors were affecting fry production. The spawning behavior of one male with two females is described. Nesting success for the two spawning seasons was 67% and 77%, respectively, with an average of 3,943 fry rising off each nest. Nest fanning by males did not measurably increase egg survival but did reduce mortality of sac-fry. Egg mortality was highest in the nests of smaller males (less than 400 mm) with large egg deposits. A water level drop was considered the primary cause for the lower nesting success in 1971.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1975)104<83:FAFPOS>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor

摘要:

A difference was found in the summer distribution of underyearling brook trout, Salvelinus fontinalis (Mitchill), and planted rainbow trout, Salmo gairdneri Richardson, in Castle Lake, California. Brook trout underyearlings oriented to the bottom and were found primarily in shallow water on the eastern shore of the lake near springs. The rainbow trout underyearlings were more pelagic and were found in the littoral areas along the entire shoreline.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1975)104<88:FADOUB>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor

摘要:

A 22.7 m3s discharge, which is at least 150 times normal summer discharge, reduced the population of marked young-of-the-year trout by 96% in the 49-day interim between the June 1972 preflood and August 1972 postflood samples. Other year classes decreased, but less dramatically. Mortality for young-of-the-year between August 1972 and October 1972 was negligible. The standing crop of trout was reduced from 26.4 kg/hectare in June to 21.9 kg/hectare in August. Of the surviving trout, 28.3% moved out of the section in which they were marked. No fish was recovered more than 1,220 m from the section in which it was marked.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1975)104<96:FATROH>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor

摘要:

A field study investigating the role of groundwater in trout spawning was conducted on Poplar Creek in northern Lower Michigan during 1969-1971. Seventy-eight natural brown trout (Salmo trutta) redds were instrumented with Mark VI standpipes during the study. Three Vibert boxes, each containing 100 fertilized brown trout eggs, were buried near each standpipe. Periodic measurements were made of gravel permeability, apparent water velocity, dissolved oxygen, temperature, and sand content of the redd gravels. Extensive measurements showed temperatures of 8.5 to 10 C and dissolved oxygen contents of 2 to 8 mg/liter in the groundwater at considerable depth beneath the streambed. The density of redds was the same in areas with or without groundwater inflow. Where there was groundwater inflow, the trout preferred zones of intermediate surface-groundwater mix, but avoided zones of undiluted groundwater inflow. Redds had higher and less variable temperatures as the percentage of groundwater increased. This resulted in earlier egg hatching. However, eggs survived in all redds regardless of the presence or absence of groundwater. Redds without groundwater inflow had temperatures closely approximating the generally colder surface water. There were no measurable changes in intragravel permeability, velocity, dissolved oxygen, or sand content of the redds as groundwater inflow increased.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1975)104<100:SEOGOB>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor

摘要:

The temperature and dissolved oxygen content of intragravel water were measured in three Oregon coastal streams between June 1968 and June 1969. In 1966, the watershed of one stream had been completely clearcut, and that of a second stream partially clearcut in staggered settings. A third watershed was left unlogged.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1975)104<111:EOLOWT>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor

摘要:

We identified the low oxygen concentrations that significantly decreased survival of largemouth bass (Micropterus salmoides) embryos incubated at three temperatures in both stationary and moving containers. Embryos developed and hatched at oxygen concentrations as low as 1.0, 1.1, and 1.3 mg/liter at temperatures of 15, 20, and 25 C, respectively, but concentrations below 2.0, 2.1, and 2.8 mg/liter significantly lowered survival. Most mortality at these oxygen concentrations occurred during hatching. At oxygen concentrations below 1.0 mg/liter, survival during the prehatching period was higher among those groups of embryos that were moved slowly up and down during incubation than among unmoved embryos; however, moved embryos suffered nearly complete mortality during hatching at all oxygen concentrations.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1975)104<122:SOLBEA>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor

摘要:

The effect of dissolved oxygen (DO) concentration on acute toxicity of cadmium to the mummichog, Fundulus heteroclitus (L.), at selected salinities was studied. Fish were acclimated to either test salinities (10, 20, 32 ‰) or to 32 ‰ and then exposed at 10 and 20 ‰. Levels of DO between 4 mg/liter and saturation did not significantly influence the tolerance of fish to cadmium poisoning in 96 hours, regardless of salinity and acclimation regime.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1975)104<129:EODOCO>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor

摘要:

Regeneration of caudal fins in Fundulus was retarded by treatment with 10 μg/liter (10 ppb) of DDT, Malathion, Parathion, and Sevin. Although DDT was quite toxic to the fish, it did not retard regeneration as much as the other insecticides, showing significant retardation only after 2 weeks. The other three which retarded regeneration to a greater extent are all acetylcholinesterase inhibitors. There may be a relationship between acetylcholinesterase inhibition and fin regeneration, although the effect on regeneration was probably not directly related to this enzyme's inhibition.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1975)104<135:ROFRIF>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor