ISSN:0002-8487    

DOI:10.1577/1548-8659-118.5.461

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

The coastal cutthroat troutOncorhynchus clarki clarkioccurs along the Pacific coast of North America from Humboldt Bay, California, to Prince William Sound, Alaska, in a zone that closely overlaps the coastal rain forest belt. This species exhibits anadromous, potamodromous stream-dwelling, potamodromous lake-dwelling, and headwater stream-resident life history forms. Anadromous fish spawn in small tributaries from late winter through spring, depending on the locality. Juveniles remain in streams for two or more years and congregate during their early months in habitats along stream edges. Later, they move to pools unless coho salmonO. kisutchare present, in which case they are driven to riffles. Most anadromous cutthroat trout juveniles smolt at age 2 if they migrate to sheltered saltwater areas or age 3 or 4 if they migrate to the open ocean. Seaward migration peaks in May, and the fish remain close inshore while in salt water. The fish seldom overwinter at sea but return to rivers in the fall or winter of the year they go to sea. In some instances, these are overwintering migrations only, because anadromous female cutthroat trout seldom spawn before age 4. Potamodromous forms migrate to main-stem rivers or to lakes; otherwise, their life history characteristics are much like those of the anadromous form. Headwater stream-resident cutthroat trout become sexually mature as early as age 2, but seldom live beyond age 4 or 5. These fish exhibit only limited instream movements and generally live out their lives within 200 m of their birthplace.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1989)118<0463:CCTALH>2.3.CO;2

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

Rheotactic behavior of young Arctic graylingThymallus arcticusfrom two populations that spawn in inlet or outlet streams of a lake and from reciprocal crosses between the two populations was tested in an artificial stream at flow velocities up to 7 cm/s. Fertilized eggs from wild fish and the resulting young from the two populations were incubated and reared under identical conditions in a hatchery before being tested. Young fish from both populations (referred to as inlet and outlet young) were tested at the time of initial swim-up and at 11–41 d after swimup. Outlet young had a significantly greater tendency to swim upstream than inlet young at temperatures of 10 (newly emerged but not older young), 12, and 16°C under both full (10.1–15.6 μmol·s−1·m−2) and dim (0.03–0.05 μmol·s−1·m−2) light conditions. Young from reciprocal crosses had intermediate responses at 12 and 16°C. However, both outlet and inlet young had similar, very weak, upstream responses when tested in darkness or (except for newly emerged young) at 10°C. Directional responses to water current appeared to be innate and genetically based but may be subject to environmental modification.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1989)118<0474:ROYAGF>2.3.CO;2

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

Data on yields of Atlantic salmonSalmo salarfrom 59 Icelandic rivers were analyzed with data on streamflows and sea and air temperatures in an attempt to identify why some stocks exhibited more variable yields than others. A group of 24 northern and northeastern rivers, which flowed into seas with wide annual variations in climatic and oceanic conditions (as indicated by coastal sea and air temperatures), exhibited significantly greater variation in Atlantic salmon yields of both grilse and two-sea-winter fish (two winters at sea before first spawning) than the 31 western rivers, which flowed into seas with more stable climatic and oceanic conditions. Yields were the most varied for stocks in the northeast, the region with the greatest annual variation in sea temperatures during spring and summer – the time when smolts migrate to the sea and begin to feed. Rivers with more variable seasonal streamflows also tended to have more variable two-sea-winter Atlantic salmon yields (P< 0.05) but not more variable grilse yields (P> 0.05). However, variations in stream flows were less useful than variations in sea and air temperatures for explaining variations in yield. We concluded that climatic and oceanic factors exert important influences on the variability in yield and abundance of Icelandic stocks of Atlantic salmon.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1989)118<0482:OARIOV>2.3.CO;2

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

Spawning habitats of sockeye salmonOncorhynchus nerkain the Taku River and its tributaries in British Columbia and Alaska were studied to determine habitat use and redd characteristics in a glacial river system. We used radiotelemetry to track adult sockeye salmon to 26 spawning reaches, and 63 spawning sites were sampled for habitat characteristics. Over 40% of the sockeye salmon in the sampling area had a freshwater age of zero, and most of these spawned in main channels or off channel areas. The availability of upwelling groundwater influenced habitat use in the main stem of the river; upwelling groundwater was detected in nearly 60% of the sites sampled in main-stem areas. Spawning sites with upwelling groundwater had lower water velocities and more variable substrate compositions than sites without upwelling groundwater. Redds had two to four times more fine sediment than previously reported. The probability of use was greatest when substrate had less than 15% fine sediment, water velocity was between 10 and 15 cm/s, and intragravel temperature was between 4.5 and 6.0°C.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1989)118<0495:SHARCO>2.3.CO;2

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

We determined body size, gonad weight, fecundity, and egg size for two populations of kokanee (lacustrine sockeye salmonOncorhynchus nerka) from two tributaries to Upper Arrow Lake, British Columbia. Embryos and alevins from both populations were incubated at controlled water temperatures (2, 4, 6, 8, and 10°C) to determine survival rates, hatching and emergence times, and alevin and juvenile sizes. Embryo and alevin survival rates were similar between populations, but varied among temperatures; the lowest survival rates occurred at 2°and the highest at 6°C. Time to hatch and emergence varied inversely with incubation temperature. Alevin and juvenile size generally increased with decreasing incubation temperature. Differences in reproductive and developmental biology among populations may reflect adaptations to the specific environmental conditions experienced during spawning and development.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1989)118<0503:RADBOK>2.3.CO;2

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

Condition indices are used in fishery science as indicators of the weight-to-length relationship of a population or subgroup (e.g., strain, sex, or age category). This conversion of the two-dimensional weight-length relationship into a single statistic results in a loss of information and, in many cases, an inaccurate representation of that relationship. Fulton's condition factor (K) is based on the assumption that the slope of the weight-length relationship is 3.0. The relative condition factor (Kn) is based on the assumption that the slopes of all samples to be compared are equal to some specific value. Relative weight (Wr) is based on the assumption that the slope and the intercept of the weight-length relationship are the same as those in the “ideal” equation. Instead of providing simple, interpretable descriptions of the weight-length relationship in fish populations, all three of these commonly used condition indices have critical flaws that can result in incorrect conclusions. Relative weight is arguably the most misleading of these indices, and its use should be reconsidered before it becomes as misused as Fulton'sK. The calculation of estimates of ordinary least-squares regression parameters is a more accurate method of examining the weight-length relationships for fish populations, and I suggest that it is the preferred method for evaluation of fish condition.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1989)118<0511:TNTRTU>2.3.CO;2

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

In an attempt to distinguish between parr of ouananiche (freshwater) and those of anadromous Atlantic salmonSalmo salar, we undertook a study of meristic and morphometric variation among populations from rivers along the Quebec north shore of the Gulf of St. Lawrence. We sampled parr from six locations in 1984; two 1983 samples were used to estimate year-to-year variation in the Watshishou River. Based on the characters examined, no practical method was found for distinguishing between the two types of parr. Morphologically, ouananiche and anadromous parr exhibited significant heterogeneity and could be classified according to origin by discriminant analysis with 71.0–84.6% accuracy. Very little variation in meristic characters was evident among the populations examined.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1989)118<0515:MAMVIP>2.3.CO;2

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

Thirty adult (3.2–8.6 kg) striped bassMorone saxatiliswere tagged with ultrasonic transmitters and tracked for up to 475 d in 9,510-hectare Lake Whitney, a Texas reservoir, to determine seasonal distribution, migration patterns, and water temperatures occupied. Striped bass distribution in summer was limited to an area near the dam, where they survived temperatures as high as 29.0°C. Tagged fish generally were found in the coolest water available (27.0–29.0°C) that contained adequate dissolved oxygen (>4.0 mg/L) in summer and occupied the warmest water (7.4–8.8°C) in winter. For the rest of the year, the fish were distributed throughout available water temperatures. Beginning in autumn, most striped bass moved up the reservoir to and into the main tributaries and remained there until spring, when they returned to the main reservoir. No spawning run up main tributaries was observed in either of the two study years, possibly due to low inflows. Individual fish displayed a preference for certain areas to which they returned yearly.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1989)118<0523:DAMOAS>2.3.CO;2

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

A large data set on Ontario lakes and their fish species was examined for evidence of the influence on species richness of regional, local, anthropogenic, and methodological factors. Analysis of regional species distributions and associations showed patterns consistent with species invasion into Ontario since the last period of glaciation. A comparison of local species richness (mean richness among lakes) with regional richness pointed to a dominance of local over regional factors in determining lake species richness. A multiple regression model of species richness accounted for 48% of variance. Of the two regional factors included in the model, watershed species richness increased lake species richness and elevation decreased it. An increase in two local abiotic factors, lake area and mean depth, increased richness. Richness also increased with increasing pH, an anthropogenic factor, and increased in more recent survey years, an indicator of methodological effects. Analyses of mean species richness in relation to the presence or absence of individual species provided further evidence of sampling (methodological) effects. Overall, the results were consistent with the existing theory of island biogeography and its specific application to fishes in lakes.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1989)118<0533:FAFSRI>2.3.CO;2

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor