摘要:

Biological and physical variables influencing survival and standing crops of juvenile salmon are treated by regression analyses to determine those variables of greatest significance. Stream flow in dry seasons as indicated by rainfall proved to be the most important single factor influencing survival from age 0+ to age I+ in the presence of such other variables as standing crops of other fishes and water temperatures. A Chi-square test indicated that the various species of fish present in Barrows Stream during the 6-year study reacted to electrofishing as though they were a single species. Indications are that construction of small water storage dams at appropriate sites in the headwaters of salmon nursery areas could increase survival and growth rate of juvenile salmon occupying the nurseries.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1970)99<297:FISCAS>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1970

数据来源: Taylor

摘要:

During the autumns of 1964, 1965 and 1966, brown trout 12.0–25.1 inches (305–638 mm) in length were removed from 4.2 miles (6.76 km) of the North Branch of the Au Sable River (Dam 2-County Line), and American mergansers were harassed in the same area each winter as time permitted. The objective was to decrease losses among the smaller salmonids which would otherwise be eaten by the large trout and mergansers. Effects of control efforts were assayed by comparison of 1965–1967 angling results and population estimates with similar data accumulated on the test section and two other stream sections of the North Branch during 1961–1964 when predator manipulation was not carried on.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1970)99<312:ROPROB>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1970

数据来源: Taylor

摘要:

Food selection by a planktivorous fish, the gizzard shad, Dorosoma cepedianum, was studied in Tuttle Creek Reservoir, Kansas.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1970)99<320:SPOZBG>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1970

数据来源: Taylor

摘要:

Intestinal tracts of 541 buffalofishes, genus Ictiobus (428 bigmouth, 57 black, and 56 small-mouth) caught in 1966–69 in central Arizona reservoirs were analyzed. Bigmouth buffalo (I. cyprinellus) from Roosevelt and Apache lakes fed mostly on planktonic algae and crustaceans, with indications of a near-bottom feeding habit. Black (I. niger) and smallmouth (I. bubalus) buffalo fed on benthic macro-invertebrates, with molluscs being the most important group utilized by both species.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1970)99<333:FOBGII>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1970

数据来源: Taylor

摘要:

Age, rate of growth, spawning, and weight-length relationship of the striped searobin, Prionotus evolans, were studied. The fish were collected from Chesapeake Bight and Chesapeake Bay during 1966 and 1967. Age was determined from otoliths which had been cross-sectioned, polished, and heated. Age groups 0 to VII were represented in the sample of 803 specimens. Males and females had the same growth rate and weight-length relationship. Growth in length was rapid until the fish reached maturity at age II. Age group II averaged 221 mm fork length. The fish accomplished most annual growth between May and September. Spawning occurred from May through the first part of July.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1970)99<343:AAGOTS>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1970

数据来源: Taylor

摘要:

Juvenile pompano (Trachinotus carolinus) were collected with beach seines from Grand Isle, Louisiana, during the summer of 1968. Additional fish were obtained from Holly Beach, Louisiana, to supplement length-weight data. Length-frequency distributions of 4,082 fish were used to follow the arrival and growth of juveniles at Grand Isle. Seven waves of juvenile recruitment were recognized. The estimated time of arrival of the first wave was mid-April; the last wave arrived in early September. Other waves arrived approximately 15 to 30 days apart; the heaviest concentration of fish on the beach was from June through early August. Length-frequency data indicated that juvenile pompano grew an average of 36 mm per month, with a range from 27 to 42 mm. Water temperatures ranged from 17.5 to 34.0 C at Grand Isle. Salinities were as low as 12.5 ppt at Holly Beach and as high as 32.6 ppt at Grand Isle. Data failed to show any relationship between temperature, salinity, and the seasonal arrival of juvenile pompano at Grand Isle. The calculated length-weight relationship for juveniles in the size range 10–125 mm (total length) was log W = -4.8152 + 2.9776 log L.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1970)99<353:SOGALR>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1970

数据来源: Taylor

摘要:

The validity of age determinations from otoliths of Atlantic cod (Gadus morhuu) captured in the Gulf of Maine is demonstrated. Otoliths were obtained from fish taken in the commercial fishery and from research vessel collections. The cod were from 9.7 cm to 110.0 cm, fork length. Growth zones in the otoliths were examined to determine if one hyaline and one opaque zone are formed annually. Age distribution of the samples was compared to a plot of the length frequency distribution (Petersen method).

ISSN:0002-8487    

DOI:10.1577/1548-8659(1970)99<359:VOADFO>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1970

数据来源: Taylor

摘要:

Bluegill, Lepomis macrochirus, were held in tanks at 24 C from November 21, 1967, to February 2, 1968. Of fish given a liberal ration throughout the period, those handled midway through formed a false annulus on their scales, and those that were not handled did not. Some bluegill received a restricted ration for 3–21 days between periods of heavy feeding but were not handled during the experiment. With one exception a false annulus was formed on the scales of only those receiving no food for 10 days or more. False annuli may be caused by fish not eating for some time or not using energy from consumed food for scale growth. Some factors discussed that may be involved in false annulus formation are lack of available food, low temperature, disease, low concentrations of dissolved oxygen and photoperiod.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1970)99<363:FAFIBS>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1970

数据来源: Taylor

摘要:

Survival of artificially-fertilized ova and larvae of northern pike, Esox lucius, was estimated from embryos held in natural spawning areas in Lake Oahe and Lake Sharpe, two main stem Missouri River reservoirs. Mortalities approaching 100% during early embryonic development were associated with sudden drops in water temperature below 10 C or prolonged temperatures near 5 C. Silt deposition of 1.0 mm per day was associated with mortality of 97% or above. Following hatching available food appeared to be a more important factor in survival than temperature change or silt deposition.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1970)99<369:EIOEDA>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1970

数据来源: Taylor

摘要:

Eggs from Lake Michigan alewives (Alosa pseudoharengus) were incubated at 79 different temperatures from 42.1 to 87.0 F. Hatching occurred at 44.4–84.9 F and was optimum (38% hatched) at about 64 F. Incubation time varied from 15 days at 45 F to 3.7 days at 70 F and 2.1 days at 84 F. Time from start to finish of hatching ranged from 13 days at about 46 F to 2–3 days at 68–70 F and 1–2 days at 80–84 F. Survival of unfed larvae held at incubation temperatures increased from 3.8 days at 51 F to 7.6 days at 58–59 F and then decreased to 2.4 days at 80–82 F.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1970)99<376:TEOTOT>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1970

数据来源: Taylor