摘要:

Representatives from the States of Illinois, Iowa, Minnesota, Missouri, and Wisconsin and from the United States Fish and Wildlife Service, meeting in December 1943, formed the Upper Mississippi River Conservation Committee for the purpose of carrying on scientific investigations of the fishery and wildlife resources of the Mississippi River from Caruthersville, Missouri, to Hastings, Minnesota. Although originally planned as a post-war project, field operations were started in the spring of 1944. Field work wag divided between two units, one operating from Dubuque, Iowa, northward and one operating from Dubuque southward. Status of the fish population was determined by test-netting, and condition of the commercial and sport fisheries was checked by commercial fishing reports, contacts with commercial fishermen, and creel census. Results of preliminary studies indicate that several types of regulations will be needed in different areas because of different ecological and economic conditions.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1946)76[279:CFSOTU]2.0.CO;2

出版商:Taylor & Francis Group    

年代:1949

数据来源: Taylor

摘要:

Attention was focused on the need of a common and better understanding of the term depletion as applied to the fisheries in order to eliminate if possible the existing inexactness of thought on the subject. Depletion has been confused at various times with at least ten different ideas associated with it but which, as has been pointed out, are not synonymous at all. In defining depletion we must recognize that the term represents a condition and must not be confounded with the cause (overfishing) that leads to this condition or with the symptoms that identify it. Depletion was defined as a reduction, through overfishing, in the level of abundance of the exploitable segment of a stock that prevents the realization of the maximum productive capacity.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1946)76[283:ADODOF]2.0.CO;2

出版商:Taylor & Francis Group    

年代:1949

数据来源: Taylor

摘要:

An analysis of the yield of brook trout (Salvelinus fontinalis) and rainbow trout (Salmo gairdnerii) per unit of fishing effort at Furnace Brook, Vermont, shows how modern statistical methods can be utilized to determine the significance of changes in the relative abundance of animal populations. The data cover the 5 years from 1936 to 1940 and the analysis of covariance employed shows that there was a significant decrease in the catch per unit of effort in 1939 which was attributed to the effects of severe floods caused by the hurricane in September of the previous year. This method of analysis, although useful for supplying a measure of relative abundance, fails to provide an estimate of the actual stock on hand.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1946)76[290:TSAOCD]2.0.CO;2

出版商:Taylor & Francis Group    

年代:1949

数据来源: Taylor

摘要:

In Birch Lake, an oligotrophic lake in southwestern Michigan, rainbow trout (Salmo gairdnerii) and lake trout (Cristivomer namaycush) have been stocked at various times in an effort to make the deeper waters of the lake provide more fishing. Over a 6-year period, creel-census clerks collected stomachs of 322 rainbow trout and 25 lake trout taken by anglers. Analysis of the contents of these stomachs revealed that while the two species of trout were competing with each other for food, neither species preyed upon the indigenous cisco population nor competed with it for food. Aquatic insects and fish made up the greater part of the diet of both species of trout. The fish portion of the diet consisted largely of forage species, with yellow perch and centrarchids occurring but seldom in the stomachs. Rainbow trout took very little surface food except during late June, when there was a mass emergence of burrowing mayflies, and in October and early November when many terrestrial insects were consumed.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1946)76[301:AAOTFH]2.0.CO;2

出版商:Taylor & Francis Group    

年代:1949

数据来源: Taylor

摘要:

On July 23, 1947, a 1-mile section of Back Creek, treated the previous year with a DDT suspension with little damage to fish, was re-treated with an oil spray at the same rate (1 pound per acre). The oil spray killed about six times as many fish as the suspension formula.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1946)76[315:RTOSAO]2.0.CO;2

出版商:Taylor & Francis Group    

年代:1949

数据来源: Taylor

摘要:

In an attempt to evaluate lake-survey procedures some of the chemical, physical, and biological measurements that have been considered possible indices of lake productivity have been examined in the light of 11 years of lake surveys and 6 years of pond rearing of yellow pikeperch. In Minnesota waters total alkalinity and total phosphorus appear to be the most valuable indices. Nitrogen is usually present in excess; sulphates are of most value in considering waterfowl areas; and chlorides, pH, and dissolved carbon dioxide are of little value in comparing waters and judging potential productivity. Potassium, manganese, and iron concentrations also are discussed. Quantitative plankton and bottom-fauna samples have been found unsatisfactory as productivity indices for ordinary lake surveys, and the distribution and abundance of larger aquatic plants are of greatest value when related to waterfowl management. In estimating the potential productivity and formulating fish-management plans for lakes the structure of the fish population and the nature of the lake basin should be considered.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1946)76[322:SIOLP]2.0.CO;2

出版商:Taylor & Francis Group    

年代:1949

数据来源: Taylor

摘要:

A review of recent European literature on pond fertilization is offered as a foundation for certain phases of American pond-cultural technique. The fertilizing substances, lime, potassium, phosphorus, nitrogen, and carbon, are discussed individually in the light of their usefulness in increasing fish yields and with regard to the important mechanisms through which they are able to effect these increases. European techniques in the employment of fertilizer are described where these are different from corresponding American procedures. In addition, an attempt has been made to integrate divergent aspects of the subject through a consideration of certain fundamentals of trophic metabolism in ponds, the function of pond soils as conservators of nutrients, and microbiological processes relating to the theory of fertilization. A synopsis of the history of pond fertilization in central Europe and a general criticism of research methods are included.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1946)76[335:DASOPF]2.0.CO;2

出版商:Taylor & Francis Group    

年代:1949

数据来源: Taylor

ISSN:0002-8487    

DOI:10.1577/00028487.1949.10492644

出版商:Taylor & Francis Group    

年代:1949

数据来源: Taylor

ISSN:0002-8487    

DOI:10.1577/00028487.1949.10492645

出版商:Taylor & Francis Group    

年代:1949

数据来源: Taylor

ISSN:0002-8487    

DOI:10.1577/00028487.1949.10492646

出版商:Taylor & Francis Group    

年代:1949

数据来源: Taylor