Radio‐transmitted electromyogram signals as indicators of swimming speed in lake trout and brown trout

Abstract

Swimming speed and average electromyogram (EMG) pulse intervals were highly correlated in individual lake trout Salvelinus namaycush (r 2 =0·52-0·89) and brown trout Salmo trutta (r 2 =0·45-0·96). High correlations were found also for pooled data in both lake trout (r 2 =0·90) and brown trout of the Emå stock (r 2 =0·96) and Laerdal stock (r 2 =0·96). The linear relationship between swimming speed and average EMG pulse intervals differed significantly among lake trout and the brown trout stocks. This successful calibration of EMGs to swimming speed opens the possibility of recording swimming speed of free swimming lake trout and brown trout in situ. EMGs can also be calibrated to oxygen consumption to record energy expenditure. 2000 The Fisheries Society of the British Isles

Use of muscle activity indices as a relative measure of well-being in cultured sea bass Dicentrarchus labrax (Linnaeus, 1758)

“…Thorstad et al, 2000). Similarly, in our study EMG signals from transmitters were rather variable, probably for inherent causes (physiological differences), or technological reasons (characteristics of the transmitter) or as consequence of electrical activity interaction between the two muscle types.…”

“…Indeed, the large gold-tipped electrodes may record a large proportion of the myotome, and sometimes multiple myomeres. Variation in depth from the skin and distance from the lateral line, where the gold rods are positioned, may affect to what extent they record EMGs from red or white muscle fibres, or both (Beddow and McKinley, 1999;Thorstad et al, 2000). Also in our study, variability of EMG at each velocity stage can be interpreted considering the possible cross-interference between the signals emitted by the two muscle types.…”

“…Calibration of swimming speed through swimming chambers to EMG signals is considered by many authors as a baseline for elucidating swimming behaviour of free swimming fish (e.g. Cooke et al, 2000;Thorstad et al, 2000;Geist et al, 2002;McFarlane et al, 2004). Some authors suggest that the relationship between EMG signal and swimming speed would be constructed for each fish before it is released, but usually calibration curves are made on a separate group of fish and then applied to the ones in the field .…”

Rainbow trout Oncorhynchus mykiss energetic responsesto pulsed flows in the American River, California, assessed by electromyogram telemetry

“…Thorstad et al (2000) found that EMGs were highly positively correlated with the fish's swimming speed. Aerobic metabolism within the red (slowoxidative) muscles governs fish's oxygen demand at any particular temperature.…”

“…The EMG radio transmitters (two types) each had two teflon-coated stainless-steel probes that led to goldplated electrodes that were embedded in the musculature of each fish to permit the detection of EMG signals (Hinch et al 1996;Thorstad et al 2000). The first type (Lotek, CEMG-R11-18, 54 mm ×11 mm diameter) weighed 11 g in air, had a 56-d life span, and recorded the cumulative electrical activity in the trout's undulating body muscle (tail beats) over 5 s per single EMG output.…”