The ultrasonic telemetry of cardiac rhythms of wild brown trout (Salmo trutta L.) as an indicator of bio‐energetics and behaviour

Abstract

A new type of miniature ultrasonic telemetry transmitter weighing less than 4 g underwater and usable on fish of less than 0.5 kg weight is described. The signal consisting of a sound pulse triggered by the QRS spike of the electrocardiogram is detectable at ranges to 400 m. Continuous records lasting 7 days were made of cardiac rhythms of brown trout. Mean heart rates were low indicating a metabolic rate of not more than 1.55 times the basal metabolic rate. Maximum heart rates were rare, occupying less than 0.5 % of the time;there was no evidence of build up of oxygen debt due to periods of high activity. Following a settling down period after the attachment of the transmitter, the fish exhibited a diurnal rhythm with higher heart rates during the day. The transition from day to night heart rates and vice versa in one fish was shown to anticipate solar altitude change by half-hour. Missing heart beats (cardiac inhibitory reflexes) are discussed as indicators of a sensory input, but they are not reliable indicators of feeding activity. It is concluded that stamina is not important for normal day to day survival of adult trout and the influence of various ecological factors is discussed.

Tracking animals in freshwater with electronic tags: past, present and future

“…Relatively cheap archival temperature tags now available on the market enable collection of long-term thermal information and large sample sizes, provided that the tags can be retrieved (for example, alligators [114], turtles [115], salmon [116]). Early sensor tags were developed by individual researchers, who would build the tags either themselves or in collaboration with engineers [112,[117][118][119]. However, many of these sensors now represent 'standard' options for commercially available tags, and their use is greatly simplified.…”

Influence of ambient oxygenation and temperature on metabolic scope and scope for heart rate in the common sole Solea solea

“…The relationship between heart rate and metabolism is not straightforward in fish (Thorarensen et al 1996). However, heart rate is liable to provide information about the environmental impact on fish physiological state, thereby widening our understanding of the general relationship between fish and their environment (Priede & Young 1977, Priede & Tytler 1977, Armstrong 1986, Lucas et al 1991. Moreover, heart rate is one of the few correlates to metabolic demand that can be monitored in free-swimming fish using telemetry (Armstrong 1986, Bushnell & Brill 1991, Lucas et al 1991, Sureau & Lagardère 1991, Claireaux et al 1995.…”

Swimming behavior and energetics of sharks

“…Instead they proposed interpreting heart rate using a quadrangle of scope, in which active and standard metabolic rates and heart rates are used to plot a line of maximum possible metabolic rates corresponding to observed heart rates. In a field study of heart rate in free-ranging trout (Priede and Young 1977), activity levels and heart rates were generally low. Thus the resultant range of metabolic rates for measured heart rates was small, and considerable information about metabolic rate could be obtained from changes in heart rate.…”

“…Heart rate has been found to be correlated with swimming activity (Sutterlin 1969, Priede 1974, Wardle and Kanwisher 1974. Priede and Young (1977) used ultrasonic telemetry to monitor heart rate from free ranging trout and made estimates of metabolic rate based on relationships between heart rate and oxygen consumption established in the laboratory (Priede and Tytler 1977). In the present study, the relationship between heart rate and oxygen consumption in the lemon shark is examined, to evaluate the potential of heart rate as an estimator of energy expenditure for free-ranging e1asmobranchs .…”

“…Rogers and Weatherley (1983) developed a transmitter to record electromyograms from the opercular musculature, but did not obtain a satisfactory correlation between oxygen uptake and frequency of respiratory movements. Priede and Young (1977) used a heart rate transmitter to obtain continuous records of cardiac rhythms from brown trout under field conditions. The fish exhibited elevated heart rates following release, corresponding with high rates of locomotory activity as determined by position fixes.…”