摘要:

Paddlefish, Polyodon spathula (Walbaum), were observed spawning over gravel bars in the Osage River, Missouri. Eggs and prolarvae were collected. Eggs were hatched and young paddlefish were reared. The external features of the egg and prolarvae, hatching, and early behavior of the larvae are described. The effect of impoundment of rivers on the paddlefish population is discussed.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1961)90[125:RAEDOT]2.0.CO;2

出版商:Taylor & Francis Group    

年代:1961

数据来源: Taylor

摘要:

Interpretation of walleye (Stizostedion vitreum vitreum) scales by three investigators revealed some differences in detail, but the data derived appeared to be basically reliable. Most fish were collected in experimental gill nets. Lengths at annuli were calculated using straight-line relationship with an intercept of 3.26 inches, total length. Growth rate of a year class, as indicated by mean length at the third annulus, was negatively correlated with abundance of the year class (r = −0.78, 11 d.f.). Walford's growth transformation did not give an entirely satisfactory fit but gave a maximum length of 31.1 inches and a k of 0.836. Variations in these values with different treatment of the data were indicated. Fitting a Walford transformation to increments gave: Lt+1= 28.8 inches (0.172) + 0.828 Lt. The correlation coefficient, r, between the annual increment indexes and the mean May to September temperatures was 0.565. Adding April and October temperatures lowered the correlation. Instantaneous growth rates, i, decrease rapidly with age and with increased length. Several indexes to growth during calendar years using i values and Parker and Larkin's Lzvalues, were tried, but the Hile increment indexes gave the best correlation with summer temperatures. Growth of female walleyes was faster than that of males.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1961)90[130:AAGOWI]2.0.CO;2

出版商:Taylor & Francis Group    

年代:1961

数据来源: Taylor

摘要:

Commercial and laboratory-prepared capillary tubes for hematocrit were tested. A 10 percent solution of heparin was found to be best for the preparation of treated capillary tubes. For examination of trout blood laboratory-prepared capillary tubes were found to be superior to commercial tubes which are designed for human blood. Sharp, pointed heparinized capillary tubes were used with good results for collecting blood from the heart without killing the examined fish. Hematocrits determined directly in such tubes were found to have the same value as those prepared in other ways.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1961)90[139:MOTMTW]2.0.CO;2

出版商:Taylor & Francis Group    

年代:1961

数据来源: Taylor

摘要:

Fish brain acetylcholinesterase is inhibited in vivo by organic phosphorus insecticides at concentrations of 0.1 mg/1 and lower. The degree of inhibition is a function of the concentration of the insecticide, the extent of exposure, specific chemical nature of the inhibiting substance, and fish species. Species used were largemouth bass (Micropterus salmoides), bluegill (Lepomis macrochirus), golden shiner (Notemigonus crysoleucas), goldfish (Carassius auratus), and fathead minnow (Pimephales promelas). Fish removed from exposure to acetylcholinesterase-inhibiting insecticides, prior to reaching lethal limits, demonstrate the capacity for regeneration of this enzyme. The time required to regenerate the brain acetylcholinesterase to normal levels depends on the extent of the initial inhibition, the specific nature of the compound producing the inhibition, and the particular species. The curve of brain enzyme inactivation and recovery, as defined by percentage changes in normal activity, describes a physiological brain cholinesterase characteristic of the fish species. The period necessary to regenerate to normal activity may be longer than 30 days. By utilization of suitable fish species it is possible to demonstrate the presence of organic phosphorus insecticides in water at concentrations of 0.1 mg/1 with exposure periods of 12 to 24 hours. Some compounds produce marked inhibition of brain enzyme activity in 6 hours. At 0.01 mg/1 Guthion produces comparable in vivo inhibition of brain acetylcholinesterase in 12 hours' exposure in several species.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1961)90[143:PEOOPI]2.0.CO;2

出版商:Taylor & Francis Group    

年代:1961

数据来源: Taylor

摘要:

Comparison of data compiled during the past 60 years with those from recent studies shows that major changes have occurred in the bottom and fish faunas of Lake Erie. The bottom fauna was formerly dominated by the nymphs of Hexagenia, but at present midge larvae and oligochaetes are most abundant. Blue pike (Stizostedion vitreum glaucum) and cisco (Coregonus artedii), which formerly dominated the commercial catch, are scarce, while other species are more plentiful than formerly. The concentrations of various major ions have increased as much as 10 p.p.m. The mean annual water temperatures are approximately 2° F. warmer today than during the 1918-28 period. Low levels of dissolved oxygen have been observed several times since 1930, and recently very low concentrations were found in the bottom waters covering many square miles of the central basin. Although similar conditions may have existed in the past, it appears that greater areas are involved at the present.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1961)90[153:ECILE]2.0.CO;2

出版商:Taylor & Francis Group    

年代:1961

数据来源: Taylor

摘要:

Selective breeding of plants and animals has been carried on for hundreds of years. Few attempts, however, have been made to breed salmon that have characteristics which would better fit the fish for the needs of modern salmon management. Experiments started in 1949 at the University of Washington to develop a selected stock of chinook salmon (Oncorhynchus tshawytscha) have shown progress in producing fish better adapted to the environment available to them. Selected stocks grow faster, are more resistant to high temperatures and disease, mature earlier, and have a higher survival rate than the non-selected stocks.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1961)90[160:SBOCS]2.0.CO;2

出版商:Taylor & Francis Group    

年代:1961

数据来源: Taylor

摘要:

The commonly used “average catch per hour” does not provide a satisfactory measure of the quality of sport fisheries because of the extreme variation in the efficiency of the angler hour. A catch rate calculated from that portion of the data which comprises the more efficient effort units is a more precise statistic, and is probably more closely related to the actual condition of the fishery and to the effects of management. Three examples of creel census data are used to illustrate a suggested method for calculating this measure of potential fishing quality, and a standardized notation for presenting the results is recommended.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1961)90[165:MOPFQ]2.0.CO;2

出版商:Taylor & Francis Group    

年代:1961

数据来源: Taylor

摘要:

Mooneyes (Hiodon tergisus) are very scarce in the upper three Great Lakes since only four specimens have been received from Lake Michigan, one from Lake Huron, and none from Lake Superior. The published statistics of the mooneyes are erroneous. Those of 1931 of Lake Michigan were perhaps chubs (Coregonus spp.) and those of Lake Huron of 1929 were also chubs and of 1934, 1949, and 1951 were gizzard shad (Dorosoma cepedianum) but since 1956 were alewives (Alosa pseudoharengus). Mooneyes are common in Lakes Erie and Ontario and perhaps in Lake St. Clair but are commercialized only in the States of Ohio and Michigan. Virtually all Lake Erie mooneyes were caught in trap nets, pound nets, and seines in less than 35 feet of water. Their life-history data collected in 1927-31 included lengths and weights of age-groups I-VII, calculated increments and lengths based on both anterior radii and lateral diameters of scales, length-weight relationships, and sexual maturity. Apparently mature specimens exceeded 8.8 inches, 3.25 ounces, and age-group I.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1961)90[170:RAAGOT]2.0.CO;2

出版商:Taylor & Francis Group    

年代:1961

数据来源: Taylor

摘要:

Taste-panel studies were conducted on fish taken from four fresh-water sources which included a cold deep lake, a shallow mixed water lake, and flowages above and below the entry of effluent from industrial plants. Fish were sampled at four seasons of the year. Taste-panel members rated the fish as to acceptability and described any unusual flavor or aroma noted. Statistical treatment of the data demonstrated that walleye (Stizostedion vitreum vitreum) taken from the source below the entry of effluent from industrial plants generally scored significantly lower than those from other sources. This trend was not as pronounced for carp (Cyprinus carpio) or for northern pike (Esox lucius). A predominance of undesirable descriptive terms was evident for the fish representing the lower-scoring source.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1961)90[175:FAAOFT]2.0.CO;2

出版商:Taylor & Francis Group    

年代:1961

数据来源: Taylor

摘要:

The assumptions necessary to obtain a valid estimate of survival rate from a single catch curve are discussed. An example of the best estimate of survival rate and its variance is worked out for the case that age is known exactly for the entire sample. A test for validity of the model is illustrated. Methods of estimating the survival rate are also given when some age groups are combined, when an age-length key is used, and when only a segment of the catch curve is usable. A table is provided to facilitate the estimation in this last case.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1961)90[181:CCAMR]2.0.CO;2

出版商:Taylor & Francis Group    

年代:1961

数据来源: Taylor