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  • 1
    Digitale Medien
    Digitale Medien
    The populations of fish in the River Tees system on the Moor House National Nature Reserve, Westmorland (1975)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of fish biology 7 (1975), S. 0 
    Details
    ISSN: 1095-8649
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie
    Notizen: The age, growth, population densities and annual production of an isolated population of brown trout (Salmo trutta L.) and bullhead (Coitus gobio L.) were investigated over a 5 year period in Trout Beck in the northern Pennines. Additional data were obtained from two other sites; Great Dodgen Pot Sike and the River Tees.Trout growth rates were low, particularly in Dodgen Pot Sike, but ages up to VIII were recorded. Bullhead growth rates were similar to those in the Tees at Cow Green (Crisp et al., 1974), though the Moor House bullheads had a higher survival rate. Population densities of trout ranged from 0.10–0.22/m2, with a fry contribution of 0.80%. The bullhead population in Trout Beck was sparse, generally 0.1/m2, though an 0 group value of 0.46/ma was estimated in 1967. At Tees Bridge values ranged from 2.5–7/8/m2. Most trout matured by age III, though in Great Dodgen Pot Sike only half of the females were mature at age IV.Annual production was estimated from Allen graphs. Trout production ranged from 1.02–3.50 g/m2/year, the fry contributing up to 51.5% of the total. A value of 0.48 g/m2/year was obtained for bullheads in the Trout Beck system in a year of good recruitment, whilst bullhead production at Tees Bridge was 7.43 g/m2/year, with fry and I group contributing 48.7 and 37.5% respectively. The high survival rate, irregular recruitment, and poor growth of these high altitude populations is discussed. Growth and reproductive peculiarities of the Great Dodgen Pot Sike trout are also discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1095-8649.1975.tb04632.x
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  • 2
    Digitale Medien
    Digitale Medien
    The trout (Salmo trutta) population of the Afon Cwm, a small tributary of the Afon Dyfi, mid-Wales (1995)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of fish biology 46 (1995), S. 0 
    Details
    ISSN: 1095-8649
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie
    Notizen: Data are presented from a 10-year (1984 to 1993) study of a Salmo trutta population in the Afon Cwm, a small tributary of the Afon Dyfi, mid-Wales. The stream is a spawning and nursery area for sea trout. Growth of trout within the stream can be summarized by a von Bertalanffy growth coefficient (K) of 0·310, with asymptotic length (1∞) 21·6 cm and with length at age 1 of 7·6 cm. Mean population density in the whole stream varied from year to year between 0·05 and 0·60 0-group trout m−2 and between 0·05 and 0·70 older trout m−2. Mean biomass varied, between years, from 0·1 to 3·5 g m−2 for 0-group and from 1·3 to 10·4g m−2 for older trout. Loss between 3 and 5 months of age appeared to be proportionate at about 50 to 60% and instantaneous loss rate from 5 to 53 months of age varied from 0·04 to 0·10 month−1 and was positively correlated with cohort number at 3 months of age. Production between 3 and 53 months of age varied between cohorts from 3 to 8 g m −2 live weight.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1095-8649.1995.tb01105.x
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  • 3
    Digitale Medien
    Digitale Medien
    Some observations on the growth and length: weight relationship of the South Georgia cod Notothenia rossii marmorata Fischer during the first four years of life (1975)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of fish biology 7 (1975), S. 0 
    Details
    ISSN: 1095-8649
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie
    Notizen: The paper describes the length: weight relationship and the results of back-calculating fish length from scale length for Notothenia rossii marmorata Fischer, collected in April 1961 from Leith Harbour, South Georgia.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1095-8649.1975.tb04615.x
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  • 4
    Digitale Medien
    Digitale Medien
    Prediction, from temperature, of eyeing, hatching and ‘swim-up’ times for salmonid embryos (1988)
    Oxford, UK : Blackwell Publishing Ltd
    Freshwater biology 19 (1988), S. 0 
    Details
    ISSN: 1365-2427
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie
    Notizen: SUMMARY. 1. The literature contains a number of curves relating time (days) required for median hatch (=D2) to water temperature (T,°C) for the eggs of several salmonid fishes. There are relatively few data on the relationships between time to median eyed (= D1), days) or time to median swim-up (= D3, days) and temperature.2. From published data, over most of the range 0-9.5°C, approximate relationships are D,=0.5D2 for Atlantic salmon (Salmo salar L.) and D3 = 1.7D2 for eight species of Salmo and Oncorhynchus.3. Field and hatchery tests suggest that these are useful empirical models for approximate prediction of D1 and D3 from D2 for most salmonids.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1365-2427.1988.tb00325.x
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  • 5
    Digitale Medien
    Digitale Medien
    A desk study of the relationship between temperature and hatching time for the eggs of five species of salmonid fishes (1981)
    Oxford, UK : Blackwell Publishing Ltd
    Freshwater biology 11 (1981), S. 0 
    Details
    ISSN: 1365-2427
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie
    Notizen: SUMMARY. Information on temperature (T°C) and time from fertilization to 50% hatch (D days) for five species of salmonid fishes has been used to assess several mathematical models relating D and T. No single equation gave the best fit to all five data sets. The power law with temperature correction (α), log101D= log10a+b log10 (T- α) and the quadratic, log10D= log10a+bT+b1T2 (where a, b, b1, and α are constants), each accounted for over 97 % of the variance of D and were good fits to the observed data points for all five species. There was little difference between the predictions obtained from these two equations within the range of observed temperatures. Therefore, the simpler power-law model is preferred. However, there were substantial within-species differences between values of D predicted from extrapolations of the two models from 2 or 3°C down to 0°C. When more data for low temperatures become available it will be possible to make a more objective choice of model.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1365-2427.1981.tb01267.x
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  • 6
    Digitale Medien
    Digitale Medien
    Some physical and chemical effects of the Cow Green (Upper Teesdale) impoundment (1977)
    Oxford, UK : Blackwell Publishing Ltd
    Freshwater biology 7 (1977), S. 0 
    Details
    ISSN: 1365-2427
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie
    Notizen: SUMMARY. The paper describes observations on water temperature and dissolved oxygen in Cow Green reservoir and also changes caused by impoundment to temperature, chemistry, dissolved oxygen and the discharge regime of the River Tees immediately downstream of the dam.Impoundment and river regulation have considerably smoothed-out fluctuations in discharge of the Tees and have ehminated the very low and very high discharges which were characteristic of the natural river.Reservoir water levels show an annual pattern of draw-down during summer, refilling in autumn and overflow during winter and spring. Tliermal stratification of the reservoir occurs rarely and is generally of short duration. Water temperatures at mid-reservoir correspond closely to those of water discharged from the reservoir. The temperature regime in the river downstream is modified as follows:〈list xml:id="l1" style="custom"〉1reduction in amplitude of annual temperature fluctuations by 1–2°C,2marked reduction of diel fluctuations, (3) delay of the spring rise in water temperature by 20–50 days and of the autumn fall by 0–20 days. These temperature changes could reduce the annual maintenance ration of a 10 g brown trout (Salmo trutta L.) by about 15% and delay the annual peak of metabolism by about 1 month. The effect upon growth rate of trout would be negligible.Fluctuations in ionic content at the reservoir inflow are comparatively large and can be related approximately to river discharge. Fluctuations at the outflow are smaller and appear to be largely seasonal. Regulation has not appreciably altered the dissolved oxygen content of the River Tees.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1365-2427.1977.tb01662.x
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  • 7
    Digitale Medien
    Digitale Medien
    Simplified methods of estimating daily mean stream water temperature (1990)
    Oxford, UK : Blackwell Publishing Ltd
    Freshwater biology 23 (1990), S. 0 
    Details
    ISSN: 1365-2427
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie
    Notizen: SUMMARY. 1. It was assumed that the average of twenty-four hourly temperature readings is the‘true’daily mean. For a small stream in upper Tees-dale, northern England, estimates of the daily mean were obtained from: (a) The mean of temperature readings taken at regular but less frequent intervals than hourly (twelve, six and three times per day), (b) The daily mid-point (=1/2(maximum + minimum)). (c)Spot temperatures at the two times in the day when the daily temperature trace usually crosses the daily mean value. These estimates were then compared with the‘true’mean.2. The accuracy of the estimate of daily mean decreased with reduced frequency of reading but, even at only three readings per day, was always within ±0.5°C of the true value. Consolidation of the daily estimates gave estimates of monthly and annual means within ±0.1°C of the true values.3. Nearly 96% of estimates of the daily mean based on the daily midpoint were within ±0.5°C of the true value. The estimates showed a small but statistically significant positive bias.4. Over 80% of estimates of the daily mean based on the‘first mean crossing’were within ±0.5°C of the true value and no bias could be shown.5. Estimation of daily means from temperature at the time of the 'second mean crossing’was relatively complicated and gave less satisfactory results than did the first mean crossing.6. The daily mid-point and the temperature at the time of the first mean crossing both gave a good general indication of daily mean temperatures. When consolidated to monthly or annual means the estimates were within ±0.25°C and ±0.10°C, respectively, of the true values.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1365-2427.1990.tb00287.x
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  • 8
    Digitale Medien
    Digitale Medien
    Water temperature in a stream gravel bed and implications for salmonid incubation (1990)
    Oxford, UK : Blackwell Publishing Ltd
    Freshwater biology 23 (1990), S. 0 
    Details
    ISSN: 1365-2427
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie
    Notizen: SUMMARY. 1. Water temperatures were recorded at hourly intervals in the gravel of a trout spawning area in a small stony stream at depths of 0–20 cm in 1985–86 and 0– 40 cm in 1987.2. As depth within gravel increased, the size of the daily fluctuations reduced and their time of occurrence was delayed by about 12 min cm−1′ in 1985–86 and about 6 min cm−1 in 1987.3. From October to February mean temperatures at 20 cm depth were, on average, 0.5°C higher than those at the gravel surface. This reflected elevated daily minima more than it reflected elevated daily maxima.4. From March to July daily minima were lower and daily maxima were higher in the stream than in the gravel. Consequences were: (a) an appreciable increase in mean daily range at all depths in the gravel during the summer, (b) higher daily means (by an average of about 0.4°C) in the water than in the gravel in May to August.5. Some implications for the early development of salmonid fish are considered.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1365-2427.1990.tb00298.x
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  • 9
    Digitale Medien
    Digitale Medien
    Some impacts of human activities on trout, Salmo trutta, populations (1989)
    Oxford, UK : Blackwell Publishing Ltd
    Freshwater biology 21 (1989), S. 0 
    Details
    ISSN: 1365-2427
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie
    Notizen: SUMMARY. 1. The life cycle of salmonid fishes is described.2. The performance and environmental requirements of the various life stages of the trout (Salmo trutta L.) are reviewed, (a) The literature gives predictive relationships between water temperature and rate of embryonic development, food requirements and growth rate, (b) Water temperature, intragravel oxygen supply rate, water pH, the occurrence of mechanical shock, disturbance of spawning gravels, sedimentation and water chemistry can all influence the survival of the intragravel stages, (c) The survival and/or well-being of the free-swimming stages and the success of spawning are influenced by such factors as dissolved oxygen concentration, pH, water depth, water velocity and water chemistry.3. Human activities such as impoundment, river transfer, drainage works, land improvement, afforestation and deforestation can all influence trout populations via changes in flow regime (and related effects such as sedimentation), temperature regime and water chemistry.4. Man can also influence trout populations directly by cropping for food and/or sport and by artificial stocking.5. Examples of practical application of present knowledge are given and some future research needs are listed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1365-2427.1989.tb01345.x
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  • 10
    Digitale Medien
    Digitale Medien
    A Desk Study of the Performance of Trout Fisheries in a Selection of British Reservoirs (1977)
    Oxford, UK : Blackwell Publishing Ltd
    Aquaculture research 8 (1977), S. 0 
    Details
    ISSN: 1365-2109
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Routine statistics have been analysed from a varied selection of 18 British reservoir fisheries The numbers and weights of fish caught have been compared with the numbers and weights stocked.In lowland reservoirs the “put and take” system of management is used and annual stocking rates of 40–60 fish ha-1 (c 12 kg ha-1) give catches of 20–30 fish ha-1 (c 20 kg ha-1). Higher stocking rates lead to greater catches numerically but to relatively little increase in the weight of catch per unit area. In general, the recapture of rainbow trout is greater than that of brown trout, relative to the numbers stocked.The management of upland reservoirs is complicated by the presence of indigenous trout, poorer growing conditions and lack of research into the population dynamics of fish populations in such places. A wide variety of management possibilities exist in upland reservoirs and these are worthy of thorough investigation. Stocking at rates comparable to those used in lowland reservoirs takes negligible advantage of the potential for natural trout growth in upland reservoirs and the economics of this practice would repay closer analysis.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1365-2109.1977.tb00223.x
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