摘要:

There is considerable variation in the tissue level of sulfamerazine among individual trout in a treated population. This fact may be the reason why prolonged sulfonamide therapy sometimes fails to free all trout from Bacterium salmonicida. The quantity of food given with a standard dosage of sulfamerazine has a pronounced effect on the tissue concentration of sulfamerazine; the concentration increased when the quantity of food decreased. It appears therefore, that trout should be fed at a rate very closely adjusted to their optimum feeding requirements for the best practical results. The start of treatment with high initial doses of sulfamerazine had no effect on the tissue concentration sustained by the maintenance dosage. The relative distribution of sulfamerazine in various organs and tissues of rainbow trout was about the same as in brown and brook trout. The only difference noticed was the lack of peak levels of short duration between the 8 and 10 days of treatment, which is characteristic for brook and brown trout.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1951)81[101:FSOFDT]2.0.CO;2

出版商:Taylor & Francis Group    

年代:1952

数据来源: Taylor

摘要:

A study was made of the depth distribution, feeding, and growth of the lake trout, Salvelinus namaycush, in Lake Louisa and Redrock Lake, Ontario, in 1947. In the spring the trout were widely dispersed in Redrock Lake but as surface waters warmed to 14° or 15° C. in mid-June they moved into deeper waters. During the summer months the Redrock lake trout concentrated in the lower thermocline and upper hypolimnion while those in Lake Louisa were more widespread. Both populations frequently penetrated the 15- to 20-foot zone in mid-summer up to the 18° C. isotherm. In each lake the smaller trout had a deeper distribution.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1951)81[111:ASOTLT]2.0.CO;2

出版商:Taylor & Francis Group    

年代:1952

数据来源: Taylor

摘要:

As part of an investigation of the non-game fish resources of Utah, a study of the age and growth rate of the carp was instituted. A preliminary investigation indicated that the opercular method was superior to several other methods of determining age and growth. Age and growth were calculated from the opercular bones of 330 carp collected at Ogden Bay Refuge in 1950–51. Distances to annuli were measured directly. The relationship between the posterior radius of the opercular bone and the standard length of the carp was curvilinear. Past growth was calculated with a logarithmic nomograph. Expected number of annuli on opercular bones of known age carp, agreement of ages assessed by length frequency modes and those assessed from opercular bones of the same fish, agreement of ages assessed by empirical length frequency modes with modes formed by pooled calculated lengths, agreement between ages assessed by scales and opercular bones, and increase in age with increase in size were accepted as evidence of the validity of the opercular method. Decrease in growth rate at any year of life for successive age groups is attributed to a gradual change of the environment.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1951)81[138:TOBAAI]2.0.CO;2

出版商:Taylor & Francis Group    

年代:1952

数据来源: Taylor

摘要:

To obtain information on the post-spawning movements of yellow perch that spawn in southern Green Bay, Lake Michigan, 4,172 fish caught in drop nets were marked by tagging with monel-metal strap tags attached to the right operculum and 24,799 were marked by clipping off the second or membranous dorsal fin. Marking was done during the period from May 3 to 17, 1950, at six main stations, all located in the southern end of Green Bay.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1951)81[150:MOYPMI]2.0.CO;2

出版商:Taylor & Francis Group    

年代:1952

数据来源: Taylor

摘要:

Depth distribution of the bluegill, Lepomis macrochirus Rafinesque, in farm ponds was determined by the use of fish traps. Results indicated that during summer stratification bluegills were found in greatest numbers in shallow waters. They were unable to live for extended periods of 6 to 45 hours at water depths where the dissolved-oxygen concentration was 0.3 p.p.m. or less accompanied by a carbon-dioxide concentration of 4.4 p.p.m. or more. This condition was therefore considered to be the critical combined dissolved-oxygen and carbon-dioxide concentrations for bluegills and the depth that these concentrations usually occurred was designated as the critical depth.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1951)81[162:DDOTBL]2.0.CO;2

出版商:Taylor & Francis Group    

年代:1952

数据来源: Taylor

摘要:

The Logan River flowing southwesterly through the mountains of Cache County, Utah, is comparatively cold to the mouth of Logan Canyon. The stream is characterized by steep gradient, a high velocity and relatively few pools. A total of 1,053 brown trout were examined during the course of this study; 286 were retained for age and growth determinations. The body-scale relationship is L = 40.46 mm. + 0.44185R + 0.01908R2where L equals standard length in millimeters, and R equals scale radius times 80. The relationship of standard length to weight is described by the formula W = 0.000022L2.96. The rate of growth in length of Logan River brown trout is comparable to that of several other populations. The relative weight is somewhat higher.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1951)81[171:AAGOTB]2.0.CO;2

出版商:Taylor & Francis Group    

年代:1952

数据来源: Taylor

摘要:

The Red Lakes commercial fishery is carried on in two connected lakes with a combined area of 275,000 acres. These lakes are shallow and support a large population of walleyes (Stizostedion vitreum vitreum) which is the principal commercial species. A marking study was carried on over a 3-year period to determine whether distinct populations exist in the two lakes. Monel-metal jaw tags were placed on 9,739 walleyes taken from the spawning runs of both lakes in the springs of 1949, 1950, and 1951. A total of 1,572 tags, or 16.1 percent, was returned during the 3-year period. Of the total tag recoveries 314, or 20.6 percent, moved between the two lakes. The greatest distance covered by any fish was 60 miles in 68 days and the fastest rate of travel was 41.5 miles in 33 days. The population of the two lakes was judged to be homogeneous on the basis of fish movement, similar rates of growth of fish taken from both lakes, and similar condition factor (K). Comparison of returns of marked fish at various size intervals with numbers marked in each interval suggests that mature males are completely available to the commercial nets but that females reach a size beyond which vulnerability drops appreciably. It was further demonstrated that males were not subject to exploitation before maturity but that the majority of females was subject to 1 year of fishing prior to attainment of sexual maturity.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1951)81[179:MOMWSV]2.0.CO;2

出版商:Taylor & Francis Group    

年代:1952

数据来源: Taylor

摘要:

The philosophy and actual basis for fish management in Europe, the British Isles, Canada, and the United States are compared. The problems of multiple ownership of a fishery are discussed. It is concluded that the full possibilities for fish production can only be realized through administration by a central organization representing all of the owners of a watershed. The need is stressed for united group ownership to insure proper consideration of the fisheries along with agricultural and industrial demands. Examples are cited from various countries to illustrate the need for such administration.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1951)81[197:ACOTAB]2.0.CO;2

出版商:Taylor & Francis Group    

年代:1952

数据来源: Taylor

摘要:

In 1951, winter studies were conducted at the Convict Creek Experiment Station of the U. S. Fish and Wildlife Service located at 7,200 feet elevation in the Sierra Nevada Mountains near Bishop, California. These were designed to extend knowledge of winter conditions in stream environments and to bring to light problems requiring further investigation at this season. Common stream survey methods were employed to procure and analyze data.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1951)81[202:EEOWCO]2.0.CO;2

出版商:Taylor & Francis Group    

年代:1952

数据来源: Taylor

摘要:

Israel has established fish farming with carp as the principal species. It is a successful agricultural practice because production is good and land otherwise useless is employed. Fish ponds are fertilized and fish are also fed directly with oil cake, lupin seeds, and grain husks. Production is as high as 1,750 kilograms per hectare. Research in progress and general operation of ponds is described.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1951)81[218:ROTFFI]2.0.CO;2

出版商:Taylor & Francis Group    

年代:1952

数据来源: Taylor