Importance of electrode positioning in biotelemetry studies estimating muscle activity in fish

Abstract

Red and white axial muscle activity of adult Atlantic salmon Salmo salar was examined using conventional electromyography (EMGx) and activity radio-transmitters (EMGi) at 0·5 and 0.7 body lengths (L) along the body of the fish. Critical swimming trials were conducted and maximum sustainable speeds (U crit ) were unaffected by the presence of electrodes, being 1·51 0·21 m s 1 (3.33 0.34 L s 1 ) (n=44). Regardless of longitudinal position of the electrodes within the musculature, both EMGxs and EMGis indicated increasing red muscle activity with increasing swimming speed, whereas white muscle fibres were recruited only at speeds >86 5% U crit . Telemetered EMGi signals indicated that muscle activity varied significantly for electrodes implanted at different longitudinal positions along the fish (P<0·001). These results suggest that electrode placement is an important influence affecting the signals obtained from radio transmitters that estimate activity and location should be standardized within biotelemetry studies to allow accurate and consistent comparisons of activity between individuals and species. Optimal location for electrode placement was determined to be in the red muscle, towards the tail of the fish (0·7 L). 1999 The Fisheries Society of the British Isles

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

“…Although the two transmitters differed in size, with the larger transmitters in the larger fish, the gold-tipped electrodes were identical. Because of the proportionately larger red-muscle bands in the larger (release groups 2 and 3) fish, the detection of the voltage oscillations associated with muscular activity may have been more complete, increasing EMG signals, compared with those in the smaller fish (Beddow and McKinley 1999). Regardless, both transmitter types showed similar patterns of increasing TBF, swimming speed, and MO 2 with increasing EMG signals.…”

“…The gold-tipped electrodes of the EMG transmitters were placed into the trout's lateral, red-muscle bands (Bunt 1999). The electrodes were always placed in the same relative location, regardless of trout size, midway between the tips of the pectoral fins and base of the pelvic fins, just ventral and proximal to the lateral line, because electrode placement influences the strength of the recorded voltages (Beddow and McKinley 1999). We conducted identical procedures on pilot rainbow trout (n=10) to test placement of the transmitters.…”

Comparison of the swimming ability and upstream-migration behavior between chum salmon and masu salmon

“…6). The amplitude and frequency of these pulses was directly correlated to the level of red muscle activity (Beddow and McKinley 1999;Økland et al 1997), indicating that the shift in muscle performance from white muscle to red muscle occurred between 1.5 and 2 BL·s −1 ; this result suggests that supplementary swimming effort when approaching U crit was sustained by anaerobic metabolism. Farrell (2007) indicated that the oxygen requirements should either plateau or decrease at nearly U crit because of the activation of white muscle (based on electro-myography recordings) and glycolysis (based on glycogen depletion and lactate accumulation in white muscle); however, Farrell (2007) also explained that white muscle contraction has a significant aerobic component that drives an increase in MO 2 near U crit .…”

“…Paired electrode tips were positioned approximately 1 cm apart and secured in the lateral red muscle toward the rear of the fish. These muscles are primarily used in steady, nonbursting, aerobic swimming activity (Beddow and McKinley 1999). EMG signals are generally related to swimming speed (Økland et al 1997).…”

Upstream migration of adult chum and pink salmon in the Shibetsu River

“…The EMG electrodes were inserted subcutaneously using a hypodermic needle at about a 0.7 ratio of the body length on the left side of the fish. Two electrode tips were positioned approximately 10 mm apart, secured in the lateral red muscle toward the rear of the fish, which is primarily used in steady, non-bursting aerobic swimming activity (Geroge, 1962;Beddow and Mckinley, 1999). The electrodes also appear to be sensitive to contractions of the relatively larger white muscle (McKinley and Power, 1992;Hinch et al 1996), which is recruited primarily during burst, anaerobic swimming.…”