36 
Fishery Bulletin 109(1 ) 
C 
B 
Needle location 
Figure t 
(A) Schematic diagram of needle electrode locations where resistance 
(R) and reactance ( X c ) measurements are compared between each 
set of locations. Location A is the location used in Cox and Hartman 
(2005) with needles at a depth of 5 mm, A1 is the same location but 
the needles are inserted only 1 mm deep, and locations B, C, and D 
are different from A and have needles inserted to 5 mm. (B) Boxplots 
of mean resistance and reactance values taken from five pink salmon 
(Oncorhynchus gorbuscha) from different anatomical locations. Electrode 
locations are abbreviated as follows: control (A); reinserted (Al, the 
posterior set of electrodes were moved back to the original holes and 
the anterior electrodes were removed and reinserted into the exact 
same holes as in control); below (B, where both sets of electrodes 
were removed and placed approximately 1 cm below the holes in the 
control fish (but above the lateral line); ventral (C, where electrodes 
were removed and placed on the ventral portion of the fish and one 
set of electrodes was inserted on the anterior region one centimeter 
above the pelvic fin and the second set of electrodes was placed on the 
posterior end one centimeter above the anal fin); and half distance (D, 
where the posterior set of electrodes were moved forward and placed 
below the dorsal fin at a midpoint from the lateral line). Open circles 
(O) represent outliers determined by a Grubbs test. Different symbols 
indicate differences in means. Closed circles (•) represent mean values. 
trodes. Spawning pink salmon (n= 5, mean 
fork length= 494.6 mm, standard deviation 
[SD] = 8.9 mm) were killed, measured for 
fork length and weight, and placed on ice 
for 1 hour. A fish was randomly chosen 
and placed on a nonconductive board in a 
left-facing orientation, and measured for R 
and X c for each of five electrode locations 
(Fig. 1A). This procedure was repeated for 
all five fish that were treated. Electrode 
locations were the following: 1) control (A, 
identical to measures found in Cox and 
Hartman, 2005); 2) reinserted (Al, both 
sets of electrodes were removed and rein- 
serted into the “control” holes); 3) below (B, 
where both sets of electrodes were placed 
approximately 1 cm below the holes in the 
control (but above the lateral line); 4) ven- 
tral (C, where electrodes were placed on 
the ventral portion of the fish, and one set 
of electrodes was inserted on the anterior 
region one cm above the pelvic fin and the 
second set of electrodes was placed on the 
posterior end 1 cm above the anal fin); and 
5) half distance (D, where the posterior 
set of electrodes was moved forward and 
placed below the dorsal fin at a midpoint to 
the lateral line). Measurements of R and X c 
were recorded to the nearest 0.1 ohms (Q). 
Procedure deviations 
To determine whether deviations from the 
procedures in Cox and Hartman (2005) 
would affect impedance measures, R and 
X c measurements from five different treat- 
ment were compared to R and X c measure- 
ments from the control group. Specific 
deviations were as follows 1) switched 
wires — the signal and detector leads were 
switched (by unplugging the leads while 
leaving the needle electrodes in the fish); 
2) salt — two cups of seawater (31 practical 
salinity units) were poured under the fish; 
3) conductive board — the fish was placed 
on a stainless steel conductive board; 4) 
needle size — the 28 gauge needles were 
replaced with larger 14 gauge hypodermic 
needles; and 5) needle depth — BIA elec- 
trode needles were placed in the fish in 
the same orientation as that in the control, 
except the needles were inserted to a depth 
of 1 mm rather than 5 mm. Spawning pink 
salmon (n- 5, mean fork length=543.0 mm, 
SD=20.2) were killed, measured for length 
and weight, and placed on ice. Each of the 
five fish was randomly chosen and mea- 
sured for R and X c according to control 
protocols and also for each of the five treat- 
ment methods. 
