摘要:

The effects of logging and associated road construction on four California trout and salmon streams were investigated from 1966 through 1969. This study included measurements of streambed sedimentation, water quality, fish food abundance, and stream nursery capacity. Logging was found to be compatible with anadromous fish production when adequate attention was given to stream protection and channel clearance. The carrying capacities for juvenile salmonids of some stream sections were increased when high temperatures, low dissolved oxygen concentrations, and adverse sedimentation did not accompany the logging. Extensive use of bulldozers on steep slopes for road building and in stream channels during debris removal caused excessive streambed sedimentation in narrow streams. Sustained logging prolonged adverse conditions in one stream and delayed stream recovery. Other aspects of logging on anadromous fish production on the Pacific Coast are discussed.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1972)101<1:SEOLAA>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1972

数据来源: Taylor

摘要:

Juvenile rainbow trout were examined during 1951–59 while in stream nursery areas and when migrating downstream. Their body-scale relationship was: total length (mm) = 4.06 + 2.10 scale radius (mm × 107) and relationship between length (mm) and weight (g) was W = 0.00001384L3.0426. Age composition of trout during autumn in the nursery areas averaged 68% age 0, 29% age I and 3% age II; trout in the downstream migration averaged 64% age I, 34% age II and 2% age III. Most downstream migration occurred between 21 May and 30 June, at night, on subsiding water levels and at water temperatures of 9–17 C. There was an association between numbers of juveniles in the nursery areas and numbers of subsequent downstream migrants.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1972)101<18:AGADMO>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1972

数据来源: Taylor

摘要:

Estimates were made of the sport catches of adult steelhead (Salmo gairdneri) in the North Fork of the Stillaguamish River for the winters of 1962–63 (20,000 fishermen) and 1963–64 (11,600 fishermen). Average catch per fisherman was 0.25 fish per day in the first season and 0.35 in the second. Total catches were approximately 5,000 and 4,000 steelhead, respectively. Releases from semi-natural rearing ponds made up nearly 34% of the 1963–64 catch, while hatchery releases were about 18% of the 1963–64 catch.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1972)101<29:EOAWSF>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1972

数据来源: Taylor

摘要:

About 90% of the rainbow trout (Salmo gairdneri) roaming freely in a large pond were conditioned to come to feed at the source of an underwater acoustic stimulus in about 45 trials. The stimulus was a 150-Hz, pure tone broadcasted continuously for one minute before and throughout feeding. The fish showed no tendency to discriminate between the conditioning tone and a 300-Hz tone produced in tests from the same sound source.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1972)101<35:IAOPRT>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1972

数据来源: Taylor

摘要:

Ultrasonic tracking of mature cutthroat trout (Salmo clarki) from Little Thumb Creek displaced to the open water of Yellowstone Lake in 1969 suggested, but did not conclusively demonstrate, that trout from the west side of the lake have a westward compass mechanism, similar to the eastward compass mechanism of east side trout. Anosmic trout from Clear Creek made variable movements, but some exhibited the same patterns as control trout and horned. Experimental trout and control trout from Clear Creek retained prior to ultrasonic tracking under a 6 hr early photoperiod and a normal photoperiod, respectively, exhibited similar movements, most of which were eastward or southeastward as is typical of Clear Creek trout. Either they do not use a time-compensated sun compass mechanism, or we were unsuccessful in shifting the biological clock. Cloud cover apparently did not alter fish movement patterns.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1972)101<44:FUTATS>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1972

数据来源: Taylor

摘要:

The exotic alewife (Alosa pseudoharengus) has become exceedingly abundant in Lake Michigan. During May-August, they migrate to inshore waters to spawn and may provide an abundant food supply for the inshore warm-water piscivorous fishes. I examined stomach contents of 405 northern pike (Esox lucius), 112 smallmouth bass (Micropterus dolomieui), 103 walleye (Stizostedion vitreum vitreum), 43 burbot (Lota lota) and 29 bowfin (Amia calva) from Little Bay de Noc in Lake Michigan, during April-October of 1966–68 to determine their food habits when alewives were abundant and when alewives were scarce.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1972)101<55:UOABIP>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1972

数据来源: Taylor

摘要:

The Pacific ocean perch (Sebastes alutus) is an important commercial fish of the North Pacific Ocean and Bering Sea. Commercially exploitable populations extend from Kamchatka through the Bering Sea and along the Aleutian Islands to California. Heavy exploitation of the stocks off North America began around 1963, principally by stern-ramp trawlers of the Soviet Union and Japan. The original catchable biomass of the species off North America seems to have been about 3.5 billion pounds, and the stocks as of 1968 appeared to be about 39% of the original biomass. Fishermen of all nations that have participated in the fishery complain of stock depletion. Because the fishery has significantly reduced the proportion of large fish in the populations and fecundity increases at a much faster rate than length or weight in the species, a severe drop in fecundity of the populations is hypothesized. If the prerecruit populations do not compensate for the lower fecundity through increased survival and growth, a further deterioration in stock may begin in 1975. Catch levels have substantially exceeded the only published values for maximum sustainable yield. There seems to be little hope for a moratorium on the fishery for the extended period that would be required for this slow-growing species to recover, and replacement by a faster growing and perhaps less desirable species is possible.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1972)101<64:RISOTP>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1972

数据来源: Taylor

摘要:

Estimates of instantaneous total mortality for eastern tropical Atlantic yellowfin tuna range from 1.52 to 2.32. First capture for most probable maximum yield per recruit should occur between ages 1.9 and 3.3. Within this range the values of age at first capture tend to cluster around 2.5 years, or about 100 cm and 22 kg.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1972)101<75:YEFETA>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1972

数据来源: Taylor

摘要:

The life history of two populations of Etheostoma olmstedi Storer in the Patuxent River, Maryland, one in cold reservoir tailwater and the other in sewage-polluted water, was studied to determine the effects on this species of man-made modifications in the stream. The spawning season was in May and June with temperatures approximately 12.5–14.5 C in the cold tailwater and 16.0–18.5 C in the sewage-polluted water. In the sewage-polluted water, the fish grew faster in early summer of the first year than those in cold tailwater, but later on growth in length slowed down, even though the condition factor continued to increase. Fecundity in the sewage-polluted water population was larger than that in the cold tailwater population because of larger body weight. In the sewage-polluted water, there were fewer males with a lower condition factor than females and had a higher percentage of fish in the II-year class and a lower percentage in the I-year class than the cold tailwater population. Males did not grow as fast as females in the cold tailwater.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1972)101<80:LHOTEJ>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1972

数据来源: Taylor

摘要:

Local distribution of Cyprinodon variegatus Lacépède was examined with special emphasis on entrance into fresh water. One hundred and twenty localities were examined in relationship to fish faunas and water chemistry. The chemical factors examined were calcium, magnesium, sodium, potassium, chloride, alkalinity and dissolved oxygen. These factors singly or in combination had little effect on local distribution. Primary freshwater fish and especially centrarchid fishes seem to exclude Cyprinodon with the mechanism for this exclusion appearing to be competition for some resource(s).

ISSN:0002-8487    

DOI:10.1577/1548-8659(1972)101<89:FILDOC>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1972

数据来源: Taylor