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  • 1
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of fish biology 55 (1999), S. 0 
    ISSN: 1095-8649
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Movements of 60 stream-dwelling wild Atlantic salmon Salmo salar (97–118 mm), each tagged with a passive integrated transponder, were monitored during four trials in an enclosed section (24 m long, 45·1 m2 total area) of a stream at a range of densities (four, eight, 16 and 32 fish per enclosure). Patterns of space use differed markedly between individuals, with 80% of fish establishing home ranges within 8 days of introduction to the enclosure (settlers) and the remainder continuing to move throughout the length of the enclosure (non-settlers). Although aggressive interactions were quite frequent and dominant fish were observed chasing subordinates, there was considerable overlap of home ranges of settlers at all densities; this was the case even at lower densities at which only a fraction of the enclosure was used by the fish. Thus, rather than adopting fixed territories, the salmon showed a high level of space sharing. Individual fish used the same local area in different ways, ranging from highly localized feeding on drifting food items to a wider-ranging strategy of specialising on benthic food. Among the fish that settled absolute growth rates were inversely related to body size, and at high densities fish lost weight. These results suggest that space use in wild juvenile salmon is more complex than a mosaic of territories, that salmon demonstrate significant variability in individual space use patterns, and that large fish may suffer disproportionately when populations are at the carrying capacity of their environment.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1095-8649
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Displacement of juvenile Atlantic salmon Salmo salar within an artificial stream was either spontaneous (fish left areas of shallow water in response to experimental reduction in water level) or imposed (fish were removed by the experimenter from areas of shallow water and placed at a distance from their home site). Prior to displacement, the fish showed a high degree of site fidelity in terms of preferential use of specific areas within the stream, but the extent to which this persisted once they had left/been removed from their preferred sites was variable. Direction of displacement was not a critical factor, but homing was significantly less likely to occur following spontaneous as opposed to imposed displacement. In the case of imposed displacement, fish that were more strongly site attached prior to displacement were more likely to return to their home site after this manipulation.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of fish biology 53 (1998), S. 0 
    ISSN: 1095-8649
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: This paper describes an experimental study of the effects of food supply, growth rates and social interactions on homing by juvenile Atlantic salmon Salmo salar in response to displacement. Groups of five fish were housed in a section of an artificial stream and given either rations allowing maximum growth (the rich condition) or 0·1 of this amount (the poor condition); daily specific growth rates were significantly higher in the rich condition. After a 6-day settlement period, the fish were captured, displaced downstream and their movements recorded over the next 3 h. Prior to displacement, the fish showed a high degree of site fidelity and high levels of aggression. Dominant fish and those with stronger site attachment grew faster prior to displacement, these effects being independent. Following displacement, 24% of all fish returned to their previously favoured site and stayed there, 23% returned home initially, but subsequently moved on, 5% settled in a new site and 49% failed to move. The distribution of responses was identical for the rich and poor conditions, but fish that homed were dominant and had grown faster during the pre-displacement period.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Cambridge : Cambridge University Press
    The @classical quarterly 48 (1998), S. 447-455 
    ISSN: 0009-8388
    Source: Cambridge Journals Digital Archives
    Topics: Classical Studies
    Notes: In Poetics chapter 9, Aristotle claims that the poet's function differs from the historian's. The historian should describe what has happened, but the poet should say ‘what sorts of thing might happen, that is, the things possible according to likelihood or necessity’ (1451a36–8). The difference is not between fiction and non-fiction. Some past events happened according to likelihood and are thereby candidates for poetic representation (1451b29–32). Rather, the poet differs from the historian with respect to the level of abstraction at which he considers the actions and experiences of agents. The historian should engage in accurate and thorough ἱστορ⋯α—‘research’ or ‘fact-gathering’—by carefully recording his or others' observations of particular events. The poet, on the other hand, looks for causal relations among fictional or non-fictional events, for he cares whether his composition has a plot with events that happen because of other events and not merely after them (cf. 1452a20–l). The poet may discern in the historian's materials some causally related events fit for dramatic or epic representation, but that is not the historian's concern. As Aristotle says in chapter 23, the historian should report ‘whatever befell one or more people during a particular period of time, each of the events relating to the others by chance’ (1459a23–4). The last clause is an overstatement; we have just noticed Aristotle's admission that some past events were likely to happen. Also, he elsewhere says that ‘future events will for the most part be like past events’, presumably because they share a similar causal structure (Rh. 1394a8). The remark's point is clear enough, though: the historian should report what happened whether or not the events exhibit explanatory coherence.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of fish biology 48 (1996), S. 0 
    ISSN: 1095-8649
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: A system for monitoring automatically the movements of individually identified small fish in natural habitats is described. The system incorporates novel flat-bed antennae to detect the passage of miniature passive integrated transponders.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of fish biology 54 (1999), S. 0 
    ISSN: 1095-8649
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The movements of adult Atlantic salmon were recorded as they approached, entered and ascended the pool-and-orifice fish ladder at Pitlochry Dam, Scotland. Thirty-nine returning salmon were captured in the River Tummel by rod-and-line angling, radio-tagged and released near where they were caught. The subsequent movements of each fish were then monitored. An electronic fish counter collected additional data on movements of untagged fish past a fixed point in the ladder. Of the 39 fish that were radio-tagged, 29 individuals were recorded approaching and ascended the ladder. The remaining fish either did not approach the dam (three fish), approached the dam after detailed tracking had ended (two fish), were recaptured by anglers (three fish), or the radio tags failed (two fish). Salmon released earlier in the year delayed longer before first approaching the dam. Delays between first approaching the dam and ascent of the ladder were greater for fish that approached the dam earlier. The majority of salmon visited the ladder entrance more than once (maximum 10 visits) before ascending. Having entered, all but four salmon ascended the fish ladder successfully on their first attempt. The four individuals that failed to do so succeeded on their second attempt. The rate at which salmon ascended the ladder was related directly to temperature. The shortest ascent time of a radio-tagged salmon was 5·25 h. Movements of eight of 11 tagged fish through the ladder ceased with the onset of darkness but continued on the following morning. No radio-tagged fish entered the ladder at temperatures below 9) C. Similarly, few untagged fish were recorded ascending the ladder by the electronic fish counter at water temperatures below 8·5) C. Records from the fish counter indicated that 92% of upstream movements were made during daylight.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of fish biology 52 (1998), S. 0 
    ISSN: 1095-8649
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The percentage contribution of heart rate (fH) to change in oxygen consumption (V o2) was examined in relation to body weight and across the metabolic scope of pike. Also the consequences of variability around the regression relating V o2 and fH for estimating V o2 were considered. The percentage contribution of fH was calculated using two equations, one that ignored and one that included an estimate for oxygen consumed by the gills and absorbed across the skin (V o2s). Using both equations the percentage contribution of fH calculated using maximum and resting values for fH and V o2 decreased with weight of pike. The omission of V o2s, resulted in erroneously high estimates of the percentage contribution of fH for pike of any given weight. The omission of V o2s resulted in erroneously high estimates of the percentage contribution of fH over the region of the metabolic scope where fH is related linearly to V o2, whereas the equation that included V o2s resulted in the expected value of 100%. Assuming zero experimental error and under normoxic conditions, the 95% confidence limits for single estimates of V o2 from 30–60-min readings of heart rate are ±39% at a heart rate of 30 beats min −1. Averaged over longer periods the error decreases, and used over several days to estimate meal size the error is of the order of 1%.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of fish biology 54 (1999), S. 0 
    ISSN: 1095-8649
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Movements of adult Atlantic salmon were determined as they migrated through Loch Faskally, a 4-km long hydroelectric reservoir in North-east Scotland. The horizontal and vertical movements of four salmon were monitored for periods of 4–7 days using depth-sensing acoustic transmitters in June–July 1995. Each fish began sustained directed upstream movements within 5·5 h after release at swimming speeds of 0·15–0·40 bl s−1. Three fish reached the head of the loch after 7·25–17 h, but then returned downstream. The four fish remained in the upper half of the loch for 15–51 days, making localized movements. Mean depths of fish were 3·7–4·0 m (max 20·7 m). Two fish were recorded at significantly shallower depths at night than during the day. Departure from the loch coincided with periods of high water flow into the reservoir. In May–July 1996, 17 radio-tagged salmon entered Loch Faskally and reached the head of the loch in 3 h–5·8 days (mean 39 h). The durations of stay in the loch varied from 3 h 50 min to 67·4 days (mean 10·9 days). Only two radio-tagged salmon left the loch under conditions of high water flow into the loch.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of fish biology 50 (1997), S. 0 
    ISSN: 1095-8649
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Fork length was measured in two groups of salmon parr (32–139 mm, frozen in a straight posture and frozen in a curved posture) before (L1) and after (L2) freezing and thawing. All the fish shrank. The decrease in length was significantly greater in the curved fish than the straight fish. The absolute reduction in length (L1–L2) was related directly to L1, whereas the percentage reduction in length [(L1–L2)/L1× 100] was related inversely to L1.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of fish biology 50 (1997), S. 0 
    ISSN: 1095-8649
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: In April and May of 1993, 12 of 14 brown trout (202–288 mm), tagged with radio transmitters and displaced over 800–3600 m in a natural river system, returned to the areas from which they were captured. Homing was generally directed and rapid (up to 1·22 body lengths s−1 against the flow). Homing commenced within 65 min of displacement for four of five trout displaced downstream, and within 4 days for those displaced above the confluence of a home tributary burn with the main stem of the river.
    Type of Medium: Electronic Resource
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