摘要:

We monitored the movement and habitat use of 34 stream-dwelling smallmouth bassMicropterus dolomieuiin Jacks Fork River, Missouri, by radiotelemetry. Observations were made 24 h/d in all seasons. Definite patterns of diel activity and habitat use were evident and were modified by seasonal changes in water temperature. Fish remained in restricted home ranges for most of the year but tended to disperse in spring when all of the radio-tagged fish left their home pool; 75% returned during the same season. Equal numbers of fish moved upstream and downstream. However, the median distance moved upstream was greater. Intrapool movement of smallmouth bass peaked soon after sunrise and again after sunset in all seasons. Average intrapool movement was 120 m/d when water temperatures were lowest (4°C) and 980 m/d when temperatures were highest (27.5°C). In the warmer seasons, fish preferred logjams and root wads by day and increased their use of boulders at night. In cooler seasons, fish used boulders almost exclusively. Regardless of season, open water without cover was used most during the period just after sunrise but was never used in proportion to its availability. Boulders were the most preferred substrate, and gravel was the least preferred. Small mouth bass used intermediate depths the most and showed no daily or seasonal changes in depth preferences. Fish preferred velocities less than 0.2 m/s at all times of day and in all seasons. Movements in floods did not differ from those observed during normal discharges; however, single logs were selected in significantly greater proportion than logjams.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1989)118<0229:MAHUBS>2.3.CO;2

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

A large, multiyear (1981–1986) gillnetting data set was used to assess patterns of seasonal habitat use by striped bassMorone saxatilisin Lake Texoma, Oklahoma–Texas. Large (>2.27 kg), medium (1.36–2.27 kg), and small (< 1.36 kg but not including age-0 individuals) fish exhibited different patterns of seasonal abundance in a study area about 40 km uplake from the dam. Large fish were never taken in the study area in June, July, August, or September, or when surface water temperatures exceeded 22°C. Abundance of medium-sized fish was significantly lower during June–September and when temperatures were above 22°C than in other months and at cooler temperatures. Small fish remained abundant in the uplake area all year but were almost never collected at dissolved oxygen concentrations less than 6.0 mg/L in summer. Substantial numbers of small fish were collected at temperatures as high as 29°C, but their catch per unit effort dropped from a mean of 11.8/net at 28°C to 1.9/net at 30°C. Our results supported the thermal niche hypothesis for striped bass, and the response of small striped bass to high temperatures was similar to that reported previously.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1989)118<0243:IOWQAS>2.3.CO;2

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

Eggs, larvae, and early juveniles of striped bassMorone saxatiliswere sampled weekly from 1980 through 1985 in the Choptank River, Maryland. Yearly length-frequency distributions indicated variable survival of eggs and prolarvae (yolk-bearing larvae). Mortality of postlarvae (larvae that had absorbed their yolks) was 5–19%/d and was a decreasing function of larval size. Mortality of early juveniles was relatively low. Year-class success during 1980–1985 was significantly related to minimum water temperature during peak spawning periods and to rainfall during the early postlarval stage. Low water temperature (11–12°C) reduced the survival of eggs and prolarvae. Rainfall apparently depressed postlarval survival by creating acidic, potentially stressful, and toxic conditions.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1989)118<0251:EEOSOE>2.3.CO;2

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

We estimated population parameters for early life stages of walleye pollockTheragra chalcogrammafrom 1981 ichthyoplankton samples collected in Shelikof Strait, Alaska. Instantaneous mortality of eggs was high before peak spawning (about 0.40/d) and decreased to about 0.10/d toward the end of the spawning season. This change can be explained in part by decreasing numbers of cannibalistic juvenile and adult walleye pollock in the spawning area. The mortality of larvae 4–10-mm in standard length was generally less (about 0.09/d) than that of eggs. Total egg production estimates from egg sampling and hydroacoustic surveys of adults were 6.62 × 1014and 7.17 × 1014, respectively. Egg surveys resulted in good agreement with other methods for estimating walleye pollock biomass. Total spawner biomass estimated by the egg production method was 3.1 million tonnes, which was not substantially different from the hydroacoustic (3.4 million tonnes) or cohort analysis (2.4 million tonnes) estimates. Simulated larval abundance over time, based on daily egg production and egg and larval mortality, showed good agreement with observed larval abundance. The predicted values for total abundance of larvae in late April and late May were 18.93 × 1012and 4.21 × 1012, respectively, whereas observed values were 18.79 × 1012and 4.15 × 1012.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1989)118<0264:CDOWPI>2.3.CO;2

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

Levels of surface and subsurface fine sediment (<4.75 mm in diameter) were measured annually from 1965 to 1985 in spawning and rearing areas for chinook salmonOncorhynchus tschawytschaand steelheadO. mykiss(formerlySalmo gairdneri)in the South Fork Salmon River, Idaho. Between 1950 and 1965, logging and road construction, in combination with large storm events of 1964 and 1965, resulted in the delivery of increased amounts of fine sediments to the South Fork Salmon River. Surface and subsurface fine sediment levels peaked at 46% of the surface area in 1966 and 48% of the volume in 1969, respectively. A logging moratorium initiated in 1965, coupled with natural recovery and watershed rehabilitation, led to significant decreases in the amounts of fine sediments delivered to and stored in the South Fork Salmon River; this reduction led to a limited resumption of logging operations within the watershed in 1978. By 1985, surface and subsurface sediment levels in chinook salmon spawning areas averaged 19.7% of the surface area and 25.4% of the volume, respectively. However, additional recovery to prelogging fine sediment levels is probably contingent on both further watershed recovery and the occurrence of flood flows capable of transporting material downstream. An equilibrium between incoming sediment from the watershed and outgoing sediment from the river appears to have been reached under flow regimes that have occurred since 1975.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1989)118<0274:CISSAR>2.3.CO;2

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

Juvenile Chinook salmonOncorhynchus tshawytschawere collected from May to June 1980 in seven nonnatal tributaries of the lower Fraser River in British Columbia, Canada. The juveniles were collected predominantly in pools and had migrated 0.4–6.5 km up the nonnatal tributaries to reach the rearing areas. In 1981, two of the tributaries, Nathan Creek and the Brunette River, were sampled every 2 weeks from late February to late June. During this period, the mean fork lengths of juvenile Chinook salmon increased from 45 to 80 mm in Nathan Creek and from 44 to 68 mm in the Brunette River. The use of nonnatal rearing areas is of importance to the survival and productivity of juvenile Chinook salmon in the Fraser River.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1989)118<0284:ROJCSI>2.3.CO;2

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

Electrophoretic data were used to examine the stock structure of Arctic graylingThymallus arcticuscollected from the Yukon River drainage, Alaska. Arctic grayling were sampled from Grayling Lake in the Koyukuk River drainage and from three tributaries (Caribou Creek, Goodpaster River, and Volkmar River) entering a 60-km stretch of the Tanana River. Of 30 protein-coding loci examined, three (Mdh-2,Pgm-1, andSod-2, coding for malate dehydrogenase, phosphoglucomutase, and superoxide dismutase, respectively) were polymorphic. Differences in allele frequency between the Koyukuk and Tanana drainages accounted for about 5% of the observed variability, whereas differences among the collections from the Tanana drainage accounted for less than 1%. The difference observed between collections from the Koyukuk and Tanana rivers, major tributaries to the Yukon River, suggests that genetic comparisons are useful for biogeographical studies of Alaskan Arctic grayling. The small divergence exhibited among the Tanana tributaries suggests that the populations are linked by gene flow. In contrast, statistical heterogeneity within the Tanana drainage indicates that the rate of straying per generation among the populations is too low for resource managers to pool the populations as a unit of production.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1989)118<0290:GROAGI>2.3.CO;2

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

We compared growth patterns of clavicles, cleithra, opercles, medial nuchals, dorsal scutes, and pectoral fin ray sections from white sturgeonAcipenser transmontanusin California. The legibility and interpretability of growth patterns, ease of collection and processing, and relative precision of age estimates were evaluated for each structure with data collected on skeletal structures and morphometric measurements of 147 individuals ranging in size from 31 to 224 cm total length. Various methods were used to elucidate growth zones (thin-sectioning, oil and water clearing, staining, and X-ray radiography) to determine the most useful ageing technique for each structure. All calcified structures contained concentric growth zones that increased in number with the size of the fish and were interpreted as annual events. There was a direct linear relationship between size of the structures and size of the fish. Pectoral fin sections were the most practical ageing structure in terms of ease of collection, processing, legibility, and precision of interpretation. Age estimates from other structures resulted in poor precision between readers but relatively good intrareader precision. This suggests possible corroborative use with the development of better interpretive criteria and elucidation techniques. The von Bertalanffy, growth curve calculated from age estimates based on pectoral fin sections for all samples produced a growth model for white sturgeon that compared favorably with those from previous studies.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1989)118<0296:CATFWS>2.3.CO;2

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

We examined the relationship between egg number and body size for 70 steelheadOncorhynchus mykiss(formerlySalmo gairdneri) collected during 1985–1987 from the Bois Brule River and Pikes Creek, two Wisconsin tributaries to western Lake Superior. These data were compared with limited historical data from the Bois Brule River and nearby streams along the lake's north shore in Minnesota. Within the Lake Superior basin, steelhead exhibited significant variation of fecundity among spawning runs in different rivers and among years but not between spring and fall (autumn) runs in the Bois Brule River in 1985. Steelhead that spawned in Wisconsin tributaries to Lake Superior during 1985–1987 were significantly more fecund at a given size than were steelhead collected from tributaries along the north shore in Minnesota 20–25 years ago. Steelhead from Wisconsin tributaries produced egg numbers (3,000–6,900/female) similar to numbers (1,200–6,900) produced by Pacific Ocean steelhead in the same size range. Both length and weight of steelhead were strongly correlated with egg number and egg size. Age was not a good predictor of egg number. A common slope of 2.02 adequately fit all available Lake Superior data of length-fecundity relationships. The fecundity of steelhead for Wisconsin tributaries to Lake Superior can be estimated from the average equation for recent data from the two Wisconsin streams, log10y= –1.46 + 1.851og10x(y= egg number;x= total length in millimeters).

ISSN:0002-8487    

DOI:10.1577/1548-8659(1989)118<0311:FOSAFS>2.3.CO;2

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

The lake troutSalvelinus namaycushis the focus of an international effort by fishery management agencies to restore this once-native species to Lake Ontario. Evaluation of reproductive success and comparisons among stocked lake trout strains require genetic markers. We used allozyme variation to make genetic comparisons among strains of lake trout stocked into Lake Ontario. Forty-two proteins presumed to be encoded by 102 loci were resolved electrophoretically; 18 loci were polymorphic. Among 16 samples from five principal origins (Finger Lakes, Great Lakes basin, northern New York–Adirondack, Manitoba, and mixed origins–Lake Ontario), the average observed heterozygosity was 0.029, and the proportion of polymorphic loci was 0.125. Significant differences occurred among the 16 samples at all 18 possible locus comparisons. The averageFstvalue was 0.14. Hierarchical analysis indicated that the variation among samples within an origin was greatest within the Great Lakes basin, which included the greatest number of samples and represented the largest geographic area. Most variation observed among samples, however, occurred among origins. The 1983 and 1984 hatchery year classes produced from the 1978 Seneca brood stock did not differ significantly. The 1981 Seneca brood stock more closely resembled the sample of wild lake trout from Seneca Lake than progeny from the 1978 brood stock. The closer affinity of the 1981 brood stock to wild Seneca lake trout may be due to the larger number of wild adults from Seneca Lake used to found these fish than was used to establish the 1978 brood stock. Siscowet (“fat”) and “lean” lake trout from Lake Superior were significantly different from each other; however, the level of variation between them was not greater than that among samples from other origins, and thus did not support recognition of siscowet lake trout as a distinct subspecies. The Jenny Lake strain possessed a genetic affinity to the siscowet sample from Lake Superior. Historical reports about the origin of this strain suggest that siscowet lake trout from northern Lake Michigan may have been used to found this strain. Therefore, the Jenny Lake strain may serve as a gene source for the establishment of the siscowet lake trout in Lake Ontario. The substantial differentiation among lake trout strains reported here supports the feasibility of using allozyme markers to identify the parental sources of naturally produced young.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1989)118<0317:GDALTS>2.3.CO;2

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor