摘要:

The early life history of northern pike was studied to determine the relationship of adult pike abundance to the strength of resulting year classes and the existence and chronology of critical survival periods, along with the nature and origin of the mortality mechanisms involved. Adult abundance and the strength of the resulting year classes were not directly related. Two critical survival periods were located, one during the embryo stage between fertilization and closure of the blastopore, and the second between hatching and the termination of the alevin stage. The mortality during these periods may result from toxic concentrations of iron compounds or from excessively rapid temperature change. Growth, food utilization, and oxygen, ammonia, and sulfide levels in the nursery slough did not appear to influence survival. Greatest survival of naturally reared fingerlings will result from stabilization of water levels in the nursery areas. Water is required for at least 3 months after egg deposition if the best survival is to be obtained.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1963)92[91:ELHOTN]2.0.CO;2

出版商:Taylor & Francis Group    

年代:1963

数据来源: Taylor

摘要:

The sustained swimming speeds of juvenile coho and chinook salmon tested in a tubular chamber at temperatures ranging from 10 to 20° C. usually were dependent on the dissolved oxygen concentration at any tried concentration below the air-saturation level. Some underyearling chinook salmon tested at 19.5° C. were notably exceptional; their performance at high oxygen concentrations was not markedly better than that observed at lower concentrations between 5 and 7 mg/1. These fish may have been anemic. Reduction of oxygen concentration from air-saturation levels to 7, 6, 5, 4, and 3 mg/1 usually resulted in reduction of the maximum sustained swimming speed of coho salmon by about 5, 8, 13, 20, and 30 percent, respectively. These percentages are based on the observed performance of the first-failing and second-failing individuals of a group of five fish used in a performance test. The corresponding estimated percent reductions of the swimming speed of first-failing fish in most of the early exploratory experiments with chinook salmon were somewhat greater, averaging approximately 10, 14, 20, 27, and 38 percent, respectively. Within the ranges of tested concentrations above the saturation levels, variations of oxygen concentration had little or no effect on the performance of wild underyearling and hatchery-reared yearling coho salmon. The performance of the wild underyearlings at tested oxygen concentrations improved progressively with increase of temperature from 10 to 15 and to 20° C.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1963)92[111:TIOOCO]2.0.CO;2

出版商:Taylor & Francis Group    

年代:1963

数据来源: Taylor

摘要:

Three short-term experiments on selectivity of cod ends with various mesh sizes for smelt, Osmerus mordax (Mitchill), were conducted in Lakes Ontario and Erie during 1961. In each experiment the paired tow method was used. Four cod ends were attached alternately to a “Western bottom trawl” fished by the MV Erie I. Estimates of percent retention within 0.3-inch length strata were obtained from a comparison of length-frequency distributions in catches made by the different cod ends fishing approximately the same population of smelt on the same date. Additional information was gained from the weight of catches by different cod ends.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1963)92[125:SOFTCE]2.0.CO;2

出版商:Taylor & Francis Group    

年代:1963

数据来源: Taylor

摘要:

Groups of brown trout (Salmo trutta) which had experienced normal and temperature-retarded growth in the hatchery were stocked in a 5-mile section of Fall Creek, New York, to compare their natural mortality rates during the season directly following spring stocking. “Normal” trout were reared in Cortland, New York, hatchery water averaging 54° F. and varying annually from 39 to 60° F.; “retarded” trout were reared in a different water supply at Cortland which remained at approximately 47° F. year-round. Observations on movement (from tag returns), rates of exploitation (from creel census), and total mortality (from electrical inventories in June and September) provided the data needed to compute natural mortality rate (n) of each experimental lot in the first and second parts of both the 1949 and 1950 seasons. Yearling and 2-year-old retarded trout usually had higher natural mortality than did yearling normals in both parts of both seasons. The higher mortality rates among the retarded trout were particularly evident in the second parts of the seasons, when higher water temperatures prevailed. At time of stocking in 1949, yearling normals had harder body fat (lower iodine number) than the yearling retarded trout. In a 6-week test in Cascadilla Creek in the spring of 1951, yearling normals again had lower natural mortality than yearling retarded trout, although water temperatures never became critically high. These findings suggest that characteristics of the hatchery water supply can influence natural mortality rate of brown trout after stocking. High-temperature acclimation may be one component of this influence, but apparently it is not the only component.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1963)92[132:EOHRCO]2.0.CO;2

出版商:Taylor & Francis Group    

年代:1963

数据来源: Taylor

摘要:

Effects of temperature, ice, and fluctuating water levels on bottom organisms and on the movements of rainbow trout were investigated in a 900-foot section of Bridger Creek in southwestern Montana from October 21, 1959, to September 12, 1960. Ninety-six bottom samples and 27 drift samples were studied. Limnephilidae were the most abundant aquatic organisms in the area. Surface ice cover had no effect on the abundance of bottom organisms except for the loss of a small number frozen in the ice at the stream edge. High flows during the spring reduced the number of bottom organisms in situ, and increased the number taken in drift samples. Floating surface ice did not appear to increase the number of organisms in drift samples.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1963)92[140:WOOBOA]2.0.CO;2

出版商:Taylor & Francis Group    

年代:1963

数据来源: Taylor

摘要:

Variability and reliability of counts of fish made by divers in sections of two British Columbia rivers are examined. Repeated counts of several species of fish by a team of divers in a stream section are reasonably homogeneous, and not markedly different from total numbers subsequently recovered by poisoning. Diver counts of large spawning rainbow trout also agree closely with those made in areas with good visibility from the river bank or from helicopter. Under suitable conditions a diver team can rapidly census the fish population of long stretches of stream and obtain estimates of species composition and abundance in types of habitat difficult or impossible to sample by usual methods.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1963)92[146:UCOSFP]2.0.CO;2

出版商:Taylor & Francis Group    

年代:1963

数据来源: Taylor

摘要:

Experimental equipment, methods, and results of a number of experiments with stream bottom animals to determine the toxic effects of a packaged detergent containing 27 percent alkyl benzene sulfonate (ABS) are described.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1963)92[152:LSOTEO]2.0.CO;2

出版商:Taylor & Francis Group    

年代:1963

数据来源: Taylor

摘要:

During 1959-61, 33 landlocked salmon redds containing 24,712 eggs were excavated in two spawning areas of the Fish River Lakes to evaluate survival of naturally spawned eggs. Depth of egg deposition averaged 8 inches and ranged from 4 to 12 inches below the redd surface. The average number of eggs per redd was 749. Total egg survival to the late eyed stage averaged 93.2 percent. Average egg mortality was 4.2 percent in the pre-eyed stage and 1.7 percent in the eyed stage. Loss due to nonfertilization was less than 1 percent. Analysis of the texture of redd materials showed that 75 percent were larger than 0.25 inch, and only 12-14 percent were larger than 1.5 inches. Sand comprised 16-17 percent of the redd materials. Egg survival was apparently not affected by the amount of sand, silt, and clay in redd materials. High survival of salmon eggs in the area studied is favored by a relatively stable stream flow and lack of severe ice conditions. Superimposition of redds is not considered to be a serious factor in egg mortality.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1963)92[161:NSSOLS]2.0.CO;2

出版商:Taylor & Francis Group    

年代:1963

数据来源: Taylor

ISSN:0002-8487    

DOI:10.1577/1548-8659(1963)92[165:MOTCCI]2.0.CO;2

出版商:Taylor & Francis Group    

年代:1963

数据来源: Taylor

ISSN:0002-8487    

DOI:10.1577/1548-8659(1963)92[168:SBCOFT]2.0.CO;2

出版商:Taylor & Francis Group    

年代:1963

数据来源: Taylor