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Fishery Bulletin 107(3) 
conditions, water and air temperatures, hypoxia, sea 
conditions, time on deck, and handling procedures), and 
biological attributes (behavior, size, and species) (Davis, 
2002). This study demonstrated that reflex impairment 
can be used to assess vitality and survival potential of 
cod exposed to capture related stressors such as forced 
swimming, net abrasion, and air exposure. Cod showed 
reflex impairment immediately after exposure to stress- 
ors, suggesting that reflex actions are sensitive real time 
indicators that integrate neurological, hormonal, and 
behavioral states that can be related to changes in fish 
vitality and welfare (Davis, in press). Importantly, the 
testing of reflex actions did not cause reflex impairment, 
indicating that cod were not stressed by the procedure. 
Also, disturbances caused by repeated netting of fish 
from the holding tank did not affect the level of reflex 
impairment resulting from exposure to stressors. 
The RAMP curves for individuals and groups indi- 
cated that cod with less than 50% reflex impairment 
would not die and would likely recover from capture 
stress to resume normal feeding and growth. 
Similar correlations between stressor intensi- 
ty, reflex impairment, and increased mortality 
were found for several species of roundfish and 
flatfish exposed to simulated capture stressors 
(Davis and Ottmar, 2006; Davis, 2007). Future 
measurements of reflex impairment and mor- 
tality in cod caught by Danish seine and held 
in net pens can be used to validate the labora- 
tory RAMP curves for use in CBA operations. 
Experiments could be designed to expose cod 
to gradients of capture-related stressors in the 
field, to test for reflex impairment, and then 
to hold fish in the field in order to determine 
delayed mortality. Reflex impairment and mor- 
tality results from field stressor experiments 
could be compared with mortality rates that 
were predicted with the laboratory RAMP curve 
for cod. Possible differences in prediction of mor- 
tality rates between laboratory- and field-de- 
rived RAMP curves may be evident as a shift 
in the relationship between reflex impairment 
and mortality. These difference would be likely 
caused by the addition of stressor types in Dan- 
ish seine operations that were not included in 
the laboratory experiments. In general the types 
of stressors and not the intensity of stressors 
control the shape of the RAMP curve (Davis, in 
press). The RAMP curves could also be applied 
to estimate survival of escapees and discarded 
fish (e.g., Davis and Ottmar, 2006; Ingolfsson 
et al., 2007; Enever et al., 2009) and to improve 
selection of cod with high survival potential in 
tagging studies (Fowler and Stobo, 1999; Brat- 
tey and Cadigan, 2004). Also our result for time 
of delayed mortality is of interest in relation to 
tagging studies; because 94% of delayed mortal- 
ity occurred within 24 hours, holding fish for 
one day before release should reduce tagging 
mortality to negligible levels. 
Exposure to air should be avoided when pos- 
sible for cod, but if inevitable, it should be kept 
below safe levels. Air exposure was the most 
important stressor associated with mortality in 
cod with 40% mortality observed at 7 minutes, 
75% at 10 minutes, and 100% at 20 minutes 
(Fig. 2). However, during the reflex testing pro- 
cedures, air exposure of one minute or less did 
not induce reflex impairment or mortality and 
thus represents a conservative, safe level of ex- 
— i 1 1 r 1 1 
0.0 0.2 0.4 0.6 0.8 1.0 
Reflex impairment (proportion) 
Figure 4 
Reflex impairment (proportion) could predict (A) mortality 
(absent 0, present 1) in individual Atlantic cod ( Gadus morhua), 
or (B) mean mortality (proportion) in populations of cod exposed 
to combinations of forced swimming, net abrasion, and air (see 
Methods section). For individual (•) cod in (A), the sigmoid curve 
(y=l. 471/(1 + e -(x-o. 935/0. 104)) +95 % confidence intervals was 
significant (r 2 = 0.84, P < 0.001, n = 6 4). Note that many points 
overlap. For populations (A) of cod (B), defined by calculat- 
ing mean proportions for reflex impairment and mortality in 
ten combination stressor treatment groups (including control 
and 100% mortality groups), the sigmoid curve (y = l. 130/(1 + 
e -u-o. 809 / 0 . 113)) +95 % confidence intervals were significant 
(r 2 = 0.97, P<0.001, n = 10). Note that two points overlap. 
