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Local movements of freshwater eels (Anguilla anguilla L.) in western Ireland
No full textBiotelemetric techniques, now extensively utilized in fisheries research, have great potential in studies of activity patterns and individual movements of fish, as well as for monitoring physiological and environmental variables. In the case of eels these methods have been employed in a variety of marine and estuarine studies. However, telemetric studies of eels in fresh water have been much more limited. Radiotelemetry was used to monitor movements of Anguilla rostrata in Lake Champlain, Vermont, on the US/Canadian border, and of Anguilla anguilla in a small Spanish lake. Acoustic tags were used by Westerberg (1982) to track migrating silver eels, A. anguilla, through Lake Hjalmaren in Sweden. In the present study acoustic tracking methods were employed to monitor yellow eel, A. anguilla, movements in freshwater in western Ireland. The general objectives were to analyse individual movements with respect to swimming speeds, diel activity cycles, and environmental factors
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The automatic detection and counting of salmon in fresh water using the resistivity counter method
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Measurement of activity and oxygen consumption for adult lake sturgeon (Acipenser fulvescens) in the wild using radio- transmitted EMG signals
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Use of thermistors in radio tags
No full textThermistors are semiconductor devices whose resistance changes with temperature. They are used in radio tags to vary signal pulse rate with temperature and, with appropriate circuit and tag design, provide a means to telemeter animal activity. In the circuit describes here (Fig. 1) a combination of capacitors and resistive components determines transmitter pulse rate and length. Pulses become shorter as pulse rate is increased, so overall current drain (and thus tag life) remains about the same, regardless of temperature. The thermistor circuitry adds only about 0.3 g to the weight of a tag
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The effects of temporally autocorrelation data on methods of home range analysis
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Recent developments of a fixed hydrophone array system for monitoring movements of aquatic animals
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The relationship between the date of river entry and the estimated spawning position of adult Atlantic salmon (Salmo salar L.) in two major Scottish east coast rivers
No full textIn Scotland, adult Atlantic salmon (Salmo salar L.) enter the major east coast salmon rivers throughout most of the year (Calderwood 1922, Shearer 1990) although they spawn during a relatively short period in the autumn. Shearer (1990) shows that the timing of the return migration of adult Atlantic salmon (fish which have spent more than one winter at sea before returning to spawn) and grilse (one sea-winter fish) to the River North Esk is highly structured. Not only do the majority of older sea-age salmon return earlier, but within any given sea-age class the older river-age fish also tend to enter the river earlier in the season. Radio-tracking studies were carried out on two major east coast Scottish rivers, the Aberdeenshire Dee (between 1985 and 1989) and the Spey (1988 and 1989). This chapter examines how the timing of river entry is related to estimated spawning location for each sea-age class entering the river. We will also briefly consider implications for the management of salmon stocks
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An implantable data logging system for heart rate and body temperature
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A code-activated transponder for the individual identification and tracking of deep-sea fish
No full textSound propagates particularly well through water and therefore acoustical techniques are commonly applied to free-swimming fish. Successful uses of acoustic fish tags were reported as early as the mid-1950s (Trefethen 1956, Trefethen et al. 1957). Since then three types of tag have emerged in such experiments; these are continuous wave, pinger and transponding tags (Hawkins & Urquhart 1983)
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Telemetry of tail-beat frequency of Atlantic salmon (Salmo salar L.) during spawning
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