摘要:

On the basis of age-composition of fish taken by commercial nets in 1949 and 1950, the whitefish in Big Bay de Noc, in the upper Michigan peninsula, appear to be a population separate from that of northern Lake Michigan. There was a change in the age-structure of the commercial catch of whitefish in Big Bay de Noc during the period 1949 to 1954. In 1949 and 1950, several year-classes made important contributions to the catch, but after 1950, Age-III fish provided 85 to 90 percent of the annual catch. Possible reasons for this change in age-structure of the catch are discussed. With the exception of two localities in northern Lake Michigan, growth rate of whitefish in Big Bay de Noc and in the lake was similar. Annual differences in growth in Big Bay de Noc were noted. Fish of the larger year-class of 1949 showed greater first-year's growth than other year-classes, suggesting that the factors responsible for good growth may also favor high survival. Whitefish of older age-groups also showed indications of greater growth during 1949 than did fish of the same age in other years.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1957)87[190:AAGOWC]2.0.CO;2

出版商:Taylor & Francis Group    

年代:1958

数据来源: Taylor

摘要:

Multiple use program of eight San Diego, California water-supply reservoirs includes closely regulated sport fishing for warm-water fish. These reservoirs, when full, supply about 8,000 acres of fishing water on which there were 105,000 fishing trips in 1956 by which 456,000 fish were taken. Average catch has been 6.2 fish per fishing trip. The program is under the supervision of the San Diego Water Department and to protect public health, access to reservoirs is permitted only at stations manned by Water Department personnel. Here, public facilities including toilets, boats, trash cans, fishing docks, fireplaces, and parking areas are maintained. Regulations pertaining to protection of public health are strictly enforced. The recreational program, which includes camping, picnicking and hunting as well as fishing, is operated on a self-sustaining basis and without cost to water users through a fee-permit system. The fee for sportfishing is $1.00 a day. Close cooperation is had between the Water Department, Public Health and Conservation agencies and the public. No case of waterborne infection has been traced to pollution of the reservoirs despite many years of multiple use.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1957)87[200:MOSFIS]2.0.CO;2

出版商:Taylor & Francis Group    

年代:1958

数据来源: Taylor

摘要:

During the 1953–54 migration season 63 female silver salmon (Oncorhynchus kisutch) of the 1950 brood year were recovered in the traps at the University of Washington. Eggs from each female were fertilized by one male only and the eggs maintained as separate lots through hatching. Hatching was completed in most lots from 40 to 43 days after fertilization in water of about 52.5°F. The mortality of eggs was studied during three stages of development. Mortality appeared to be related more to the female than the male parent. Females arriving during the first portion of the run produced eggs that had higher survival than females arriving during the last portion of the run. Survival through hatching was 48 percent for about 198,000 eggs produced by the 63 females. This survival was considerably less than survival rates reported in the literature. A delayed entry into the ponds was associated with increased water temperature. Over-retention of the eggs may have caused the below-normal survival.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1957)87[207:STHOEF]2.0.CO;2

出版商:Taylor & Francis Group    

年代:1958

数据来源: Taylor

摘要:

Redear sunfish (Lepomis microlophus) were marked by latex injection and by fin-clipping in Wyland Lake, Indiana, to determine immediate and delayed effects of these techniques on survival. A variety of fin-clips were used and latex was injected subdermally with a hypodermic syringe in the occiput region and posterior dorsal region. From recaptures made during the year of marking and in the next year the following conclusions were drawn. (1) Survival of fin-clipped fish below and above 123 millimeters fork length was similar two weeks following marking and proportionate recaptures from these two size groups were also made a year subsequent to marking for fish carrying either a single fin-clip or a double fin-clip. (2) There was no immediate mortality from subdermal injection of latex; and survival of fish of different sizes was the same with no difference noted between the two sites of injection. (3) Survival of fish marked with posterior-dorsal latex injections was similar to that of fin-clipped fish over a year period, but fish marked with occiput injections were recaptured at a lower rate than those of the other groups. There is some evidence that the occiput injection is sloughed off. The spot may heal or it may become infected and the fish die. In either event the mark is lost. (4) Latex marking does not possess an advantage over fin-clipping from the point of view of survival. The new technique does offer an increased variety of marks, however; but careful choice of the injection site must be made, since all sites are not equally favorable.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1957)87[220:TSOFAL]2.0.CO;2

出版商:Taylor & Francis Group    

年代:1958

数据来源: Taylor

摘要:

A reanalysis of pertinent data on survival, natural mortality rates and rates of exploitation for largemouth black bass (Micropterus salmoides) is made. It is demonstrated mathematically that a size limit effective one year after the minimum size at which capture is practicable will eventually assure a greater number of large fish in the catch than is possible without a size limit under the conditions observed to date. Large fish are defined as those which are three years or more older than fish at the limiting size for capture.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1957)87[229:SLILBB]2.0.CO;2

出版商:Taylor & Francis Group    

年代:1958

数据来源: Taylor

摘要:

Changes in the fish population in Clearwater Lake during the first 7 years after impoundment, 1948 through 1954, are described. This flood-control reservoir of 1,650 acres on Black River in the Ozark Highland of Missouri was completed by the Corps of Engineers, U. S. Army, in 1948. It is mostly shallower than 30 feet, and the water is moderately hard (M. O. alkalinity 97–106 p.p.m.) and clear (turbidity usually less than 7 p.p.m.).

ISSN:0002-8487    

DOI:10.1577/1548-8659(1957)87[240:TDOTFP]2.0.CO;2

出版商:Taylor & Francis Group    

年代:1958

数据来源: Taylor

摘要:

Among the lake trout, Salvelinus namaycush (Walbaum), of eastern Lake Superior are some which, instead of spawning on reefs and shoals in the lake, enter certain rivers to spawn. Tagging and recovery studies were conducted on such fish seined from the Montreal and Dog rivers during the period 1951 through 1955. Male trout in Montreal River were found to mature at age 7 years when their average length was 25 inches. Females matured a year later when their average length was 28.5 inches. Trout in Dog River matured at the same ages but at lengths shorter by 3 to 4 inches, apparently because of slower growth during early life. Captures of the tagged trout in Lake Superior by sport and commercial fishermen showed that they frequented depths from 10 to 30 fathoms. Most of the trout recaptured were taken within 30 miles of the river in which they spawned. High recapture rates in the succeeding spawning season in the rivers at which they were tagged suggest that most of the trout return to the same river annually to spawn, and that the populations associated with each spawning run are discrete. The mortality rate of fish in the spawning run increased during the study period and reached an estimated 90 percent in both populations for the year 1954 to 1955. Spawning populations in both rivers declined from over 2,000 fish in 1952 to only a few fish in 1955. Catch of trout by sport and commercial fishermen was light, and was estimated to be less than 5 percent of the population each year. Incidence of scars caused by attacks of sea lamprey, Petromyzon marinus, greatly increased during the years when the trout population declined. It appears likely that the rapid decline of these populations of stream-spawning lake trout was caused by the increase of sea lampreys in Lake Superior.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1957)87[259:SORPOL]2.0.CO;2

出版商:Taylor & Francis Group    

年代:1958

数据来源: Taylor

ISSN:0002-8487    

DOI:10.1577/1548-8659(1957)87[281:I]2.0.CO;2

出版商:Taylor & Francis Group    

年代:1958

数据来源: Taylor

摘要:

Management of marine fisheries, when compared to agriculture, is handicapped by the small amount of influence that can be exerted in any phase of fish production except the harvest. However, fishery science can contribute to increased fish catches in several ways. Although planting of hatchery-reared marine fish has been of little use, cultivation of marine animals, particularly of molluscs, can produce increased quantities of seafood. There is a possibility of inducing artificial up-wellings of more fertile bottom waters. Scientific investigations can help avoid artificial and unnecessary limitations which restrict efficient fishing operation. Research can also point out ways to avoid waste of fish and fishing effort which results from depletion of heavily exploited stocks. Predictions of availability and of abundance and correlation of such predictions with hydrographic conditions can assist fishing operations. Studies in fish behavior and reactions under given circumstances can aid in the design and operation of fishing gear.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1957)87[282:COBAOT]2.0.CO;2

出版商:Taylor & Francis Group    

年代:1958

数据来源: Taylor

摘要:

A summary of recent technological advances in commercial fisheries is presented. Application of these can eliminate waste and loss, extend storage life of fresh and frozen fish, reduce production costs by design of production lines, develop new fisheries products, increase quality of present products, and develop new uses for processing wastes. The fishing industry must adopt new technological advances if it is to compete with other food-producing industries.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1957)87[293:IOTAOU]2.0.CO;2

出版商:Taylor & Francis Group    

年代:1958

数据来源: Taylor