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Fishery Bulletin 107(3) 
is important during haulback operations and transfer 
of fish from the seine to the boat in CBA. Moderate 
intensity of abrasion was administered in the experi- 
ment because these injuries are likely to occur during 
sorting and may increase the risk for infection, disease, 
and delayed mortality. Fish exposed to these stressors 
(air exposure, forced swimming, moderate net abrasion) 
may not have obvious external injury and the effects 
of such stressors may be difficult to assess by visual 
inspection during sorting. Moreover fish experiencing 
different levels of such stressors may differ in internal 
status and survival potential. 
Exposure to air was caused by placing fish in a tank 
without water to simulate conditions that would occur 
during sorting on deck (on the sorting table) after cap- 
ture, and the intensity of the stressor was controlled by 
altering exposure duration. The swimming stressor was 
created by forcing fish to swim against a current cre- 
ated by lowering the water level in a tank (145 cm x 145 
cmx8 cm water depth) in which water was introduced 
along the tank wall to cause a circular current of ap- 
proximately 20 cm/s. This stressor intensity was varied 
by controlling the amount of time that the fish was 
forced to swim against the current. Net abrasion was 
caused by capturing the fish in a net and sloshing them 
up and down at the water surface in a tank for a fixed 
time of one minute. After administration of stressors 
the fish were placed into a stock tank, and one indi- 
vidual at a time was taken out for reflex testing. 
The effect of exposure to air alone was tested in cod 
(n = 32) exposed to either 5, 7, 10, or 20 minutes of air 
(all at 9.0°C). After air exposure, fish were placed into 
a stock tank and then individuals were taken out for re- 
flex testing. Testing began 5 minutes after the exposure 
to air ended and was completed within 9 minutes from 
the start of testing for each exposure group (n = 8 per 
group). Fish were then held to determine mortality. 
The effect of exposure to seven combinations of swim- 
ming, net abrasion, and air was determined to simu- 
late stressors associated with capture by Danish seine. 
Replicate fish (n = 56) were exposed to swimming for 5, 
10, or 15 minutes, net abrasion for 1 minute, and air 
for 5, 10, or 15 minutes (all at 9.0°C). Then fish were 
returned to tanks and reflex testing began 5 minutes 
after exposure to stressors and was completed within 
9 minutes from the start of testing for each exposure 
group (?? = 8 per group). Fish were then held to observe 
mortality. 
Step 3: RAMP curves and statistics 
The proportion of reflex impairment in each fish was 
calculated as follows: 1 - (the sum of individual reflex 
scores /the total possible score of 7), i.e,. the proportion of 
reflex impairment was 2/7 if five out of the seven reflex 
actions (see Table 1) were present. Mortality for indi- 
vidual fish was scored as 1 (present) or 0 (absent) and 
the mortality date was noted. Statistical significance 
of correlation between reflex impairment and mortality 
was tested by using Spearman rank correlation. Sigmoid 
curves (RAMP curves) showing relationships between 
reflex impairment and mortality were fitted by using 
SigmaPlot vers. 10.0 (Systat Software, Inc., Chicago, IL). 
When control fish reflexes were sampled repeatedly, the 
effects on reflex impairment were tested with Friedman 
analysis of variance (ANOVA), whereas the effects of 
sampling time, air exposure time, forced swimming, net 
abrasion, and air exposure were tested with Kruskal- 
Wallis ANOVA. The effect of disturbance on reflexes was 
tested with a two sample /-test. Statistical significance 
was accepted at P<0.05. 
Results 
Step 1: Appropriate procedures for reflex testing 
Reflexes in control (unstressed) cod were not impaired 
by repeated testing at 0, 60, and 180 minutes after 
initial capture from a stock tank (ANOVA, F 2g =0.64, 
P= 0.728), indicating that cod were not stressed by the 
reflex-testing procedure itself. Mean reflex impairment 
(proportion) for each testing period ranged from 0.03 to 
0.06 and no mortality occurred. 
Reflex impairment occurred immediately after ex- 
posure to 5 minutes of swimming, 1 minute of net 
abrasion, and 5 minutes of air exposure and was not 
significantly changed (mean ±1 standard error) by the 
time of sampling when sampled at 0 (0.71 ±0.08), 5 
(0.65 ±0.03), 7 (0.61 ±0.05), 10 (0.50 ±0.07), or 15 min- 
utes (0.51 ±0.07) after exposure to stressors (ANOVA, 
F 34 = 7.92, P=0.095). These results indicate that reflex 
actions are real-time indicators of stress, and recovery 
does not happen within the first 15 minutes after ex- 
posure to stressors. 
Repeatedly disturbing fish (16 times) in a stock tank 
by chasing and netting fish out of the tank before net- 
ting fish for stressor treatment did not result in in- 
creased mean (±1 standard error) reflex impairment 
(0.86 ±0.08) or mortality (0.75 ±0.16) after the fish 
were subjected to 5 minutes of swimming, 1 minute 
of net abrasion, and 10 minutes of air exposure when 
compared to repeatedly disturbing fish (4 times) (reflex 
impairments. 82 ±0.08; mortality=0.50 ±0.19), after 
the fish were exposed to the same stressors (reflex im- 
pairment /-test, / 14 = 0.32, P=0.751; mortality /-test, 
/ 14 =1.00, P=0.334). 
Step 2: Exposure experiments 
Cod exposed to increased duration in air (5, 7, 10, and 20 
minutes) showed increased reflex impairment (ANOVA, 
F 31 =17.11, P < 0.001; Fig. 2). Mortality also increased 
with increased air exposure (ANOVA, P 31 =17.87, P<0.001; 
Fig. 2). Air exposure was an important stressor and mor- 
tality increased rapidly as the duration of time that fish 
were exposed to air increased, and 75% mortality was 
observed at 10 minutes of air exposure. At 20 minutes 
of air exposure 100% mortality was observed. No imme- 
diate mortality was observed from any of the air expo- 
