摘要:

An approach toward the development of a method to estimate the production rate of primary consumers in a stream was as follows: For a given unit area of stream bottom, the production rate (B) is equal to the algebraic sum of the rate of change in population density (P) and the difference between the rates of removal (R) and accrual (A):

ISSN:0002-8487    

DOI:10.1577/1548-8659(1962)91[243:AMTETP]2.0.CO;2

出版商:Taylor & Francis Group    

年代:1962

数据来源: Taylor

摘要:

The age and growth of the longnose gar in Central Missouri were determined from the branchiostegal rays. Males and femmes differed markedly in growth and longevity. One-year-old males were 19.5 inches long, and females were 22.0 inches long. Females continued to grow approximately one inch a year for 13 to 14 years, and outlived the males. Males matured between 3 and 4 years of age, and females at about 6 years of age. Sex ratios changed with the age of the fish; initially they were in favor of the males, and after 10 years, they were in favor of females. The average number of eggs per female was 27,830; range 4,273 and 59,422. The mature eggs are toxic to mice and other higher vertebrates, but are probably not toxic to fishes.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1962)91[251:CTTLHO]2.0.CO;2

出版商:Taylor & Francis Group    

年代:1962

数据来源: Taylor

摘要:

Fine-thread gill nets with meshes of 3/8-, 1/2-, 3/4-, 7/8-, and 1-inch (stretched measure) were used to sample lake-dwelling juvenile sockeye salmon (Oncorhynchus nerka) and associated small fishes in Brooks Lake, Alaska. Thirteen of 20 species known to occur in the lake were sampled with the small meshes. Sockeye salmon, Alaska blackfish (Dallia pectoralis), threespine stickleback (Gasterosteus aculeatus), ninespine stickleback (Pungitius pungitius) and sculpins (Cottus spp.) less than 50 millimeters in length were sampled. Different selectivity patterns were shown by different species in various mesh sizes. Meshes smaller than 1 inch had low catch efficiencies, although these meshes were useful for qualitative assessment of small fishes.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1962)91[263:TUASOS]2.0.CO;2

出版商:Taylor & Francis Group    

年代:1962

数据来源: Taylor

摘要:

Wide variations exist in landings of albacore (Thunnus germo) in Oregon and Washington. In 1944, Oregon and Washington landings reached 34 million pounds, but dropped to 0.6 million ponnds a decade later. Variations in landings may be a result of fluctuations in availability. Distribution of albacore along the North American coast is known to be influenced by sea temperatures. Although weather conditions and economic factors are reflected in Oregon-Washington landing statistics, it may be that annual variations in sea surface temperatures are also affecting the success of the fishery by varying availability to the fishermen.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1962)91[269:STATAO]2.0.CO;2

出版商:Taylor & Francis Group    

年代:1962

数据来源: Taylor

摘要:

In 1958 and 1959, 4,353 blue crabs of 5 inches or greater carapace width were tagged in three estuaries and at two coastal locations in South Carolina to determine coastal movement. Locations of 530 returns indicate that most of the crabs did not migrate between estuaries, but limited their movement between the lower estuary and adjacent coastal waters. It was concluded, at least for South Carolina, that management measures can probably be confined to individual estuarine systems rather than large coastal regions.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1962)91[275:BCMICS]2.0.CO;2

出版商:Taylor & Francis Group    

年代:1962

数据来源: Taylor

摘要:

Sexual maturity of striped bass, Roccus saxatilis (Walbaum), was investigated in the Albemarle Sound-Roanoke River system of North Carolina during the periods October 1956 through January 1957, October 1957 through April 1958, and April through September 1960. A method which permitted the determination of maturity through the measurement of ova was used. Percentages of mature female fish during several months prior to spawning are given by age group. At age-group VII and older, there was evidence of intermittent spawning and the possibility of cessation.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1962)91[279:SMADFO]2.0.CO;2

出版商:Taylor & Francis Group    

年代:1962

数据来源: Taylor

摘要:

Biologists frequently assume that the number of individuals in a “discrete” population follows an exponential relationship with respect to time, at least over the latter part of the life of the members. Such a discrete population may be, for example, a year class of a particular species of fish in a particular body of water.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1962)91[283:OEMCIE]2.0.CO;2

出版商:Taylor & Francis Group    

年代:1962

数据来源: Taylor

摘要:

Effects of a flies-only regulation on angling and on fall populations of wild brook trout were tested on 5,000 feet of Hunt Creek, Montmorency County, Michigan. Complete angling records and population estimates for the period 1949-54, when all sections were fished under normal state regulations, were compared with records for the period 1955-59, when sections Z and A were fished under a flies-only regulation, and B and C continued under normal rules. Yearly totals for angling load, catch, angling quality, pounds of trout creeled, small trout released, and postseason (fall) population estimates were compared. Averages for the 5 years after the lure regulation was changed were compared with averages for the years before the change for both Z and A and the B and C controls. Also, annual totals for Z and A were related to corresponding annual totals for B and C to provide ZA/BC ratios for before-and-after comparisons.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1962)91[295:EOAFRO]2.0.CO;2

出版商:Taylor & Francis Group    

年代:1962

数据来源: Taylor

摘要:

Effects of phosphorus and nitrogen fertilizers on the abundance of fish food organisms were investigated in four newly excavated ponds. Before fertilization the ponds were characterized by low nitrogen and phosphorus concentrations, pH values near neutrality, low total alkalinities, and dissolved oxygen concentrations near saturation. After fertilizers were added to three ponds, chemical and physical conditions were altered considerably by the production of large quantities of plankton organisms. Establishment of plankton populations was followed by development of benthic communities, especially in the two ponds receiving both nitrogen and phosphorus. The benthic community developed most rapidly, and the biomass became greatest in the pond receiving the heaviest applications of nitrogen and phosphorus. In ponds which received no phosphorus, benthic production was low.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1962)91[303:EOAFOP]2.0.CO;2

出版商:Taylor & Francis Group    

年代:1962

数据来源: Taylor

摘要:

A method is presented for determining the 24-hour chronology of feeding intensity in natural populations of fishes based upon stomach food analyses and digestion rate experiments. The method is illustrated by studies on a population of young black bullheads. Two distinct feeding periods are recognized, the major peak occurring just before dawn, and a minor peak shortly after dark. Little food of any kind is taken during the middle of the day or around midnight. Although several sources of error are currently recognized, the method should eventually prove valuable in the quantitative analysis of aquatic food chains.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1962)91[313:DOFCIF]2.0.CO;2

出版商:Taylor & Francis Group    

年代:1962

数据来源: Taylor