395 
Abstract — Assuring the vitality 
and survival potential of live-caught 
Atlantic cod ( Gadus morhua) is 
important for improving the sorting 
of fish before net penning operations 
designed to hold fish for growth and 
later market. When Atlantic cod are 
captured by Danish seine, the most 
commonly used fishing gear for live- 
caught fish, they undergo stressors 
such as forced swimming, net abra- 
sion, and air exposure. Laboratory 
experiments (at an air temperature 
of 9°C and water temperature of 
8°C) were conducted with the aim of 
constructing a RAMP (reflex action 
mortality predictor) curve for predic- 
tion of vitality and survival potential 
in Atlantic cod captured in Danish 
seines, by varying the levels of these 
stressors. Atlantic cod exposed to 
increased duration in air (5-20 min) 
showed increased reflex impairment 
and mortality, with 75% mortality at 
10 minutes of air exposure. Forced 
swimming in combination with net 
abrasion and air exposure did not 
increase reflex impairment or mor- 
tality above that associated with 
air exposure alone. The Atlantic cod 
RAMP curves indicated that fish 
with reflex impairment less than 50% 
would not show mortality and would 
likely recover from capture stress. 
Manuscript submitted 29 October 2008. 
Manuscript accepted 6 May 2009. 
Fish. Bull. 107:395-402 (2009). 
The views and opinions expressed 
or implied in this article are those 
of the author and do not necessarily 
reflect the position of the National 
Marine Fisheries Service, NOAA. 
Reflex impairment as a measure of vitality and 
survival potential of Atlantic cod ( Gadus morhua) 
Odd-Berre Humborstad (contact author)' 
Michael W. Davis 2 
Svein Lokkeborg 1 
E-mail address for contact author: oddb@imr.no 
1 Institute of Marine Research 
Nordnesgaten 50 
PO. Box 1870 
Nordnes, N-5817 Bergen, Norway 
2 NOAA Fisheries, Alaska Fisheries Science Center 
Fisheries Behavioral Ecology Program 
Hatfield Marine Science Center 
Newport, Oregon 97365 
In capture-based aquaculture (CBA; 
Ottolenghi et al., 2004), fish are caught 
live and held in net pens to supply 
high-quality fresh fish throughout the 
year and thereby increase the value 
of the catch, given a fixed boat quota. 
Animal welfare issues in CBA arise 
when handling stress and adaptation 
costs to new environments are added 
to the capture stress. Also the dura- 
tion of stress will increase dramati- 
cally compared to that of traditional 
commercial fishing where the human 
impacts on fish end with slaughtering 
immediately after capture. Improv- 
ing fish welfare in CBA should be 
achieved by keeping and storing only 
vital specimens after a sorting pro- 
cess. Operational indicators of vitality 
and survival potential are therefore 
needed. 
Current sorting criteria include re- 
moving specimens showing any visual 
sign of damage such as injuries from 
net abrasion and mechanical han- 
dling. Also specimens having clear 
signs of barotrauma such as gas filled 
eyes (exophthalmia) or overinflated 
abdomens due to punctured gas- 
bladders are poor candidates for live 
storage and should be removed. This 
practice combined with the use of spe- 
cialized transport tanks and net pens, 
and the implementation of careful 
handling routines and monitoring of 
water quality have greatly decreased 
instantaneous and postsorting mor- 
tality. Still some delayed mortality 
occurs in seemingly unharmed speci- 
mens because the internal status of 
the animal is not readily evaluated 
by visual inspection. Thus there is 
the potential for improving the sort- 
ing process before the transfer of fish 
to tanks or net pens by developing 
operational indicators of vitality and 
survival potential. 
To date there are several physi- 
ological and behavioral indicators of 
fish condition available; however, they 
share the unfavorable attributes of 
being expensive and labor intensive 
and are therefore not suited for rou- 
tine use in commercial fisheries. More 
importantly, although applicable for 
determining sublethal stress levels, 
they show a lack of concordance with 
mortality outcomes (Davis et al., 2001; 
Davis and Schreck, 2005). Recently, 
reflex impairment has been tested as 
an indicator of vitality and survival 
potential (Davis and Ottmar, 2006; 
Davis, 2007). Correlations between 
stressor intensity, reflex impairment, 
and increased mortality were found 
for several species of round fish and 
flat fish exposed to simulated capture 
stressors. 
The main objective of this study 
was to test whether reflex impair- 
ment could be used as a rapid real- 
time operational indicator to predict 
vitality and survival outcomes in 
fishing operations designed to hold 
Atlantic cod ( Gadus morhua, hereaf- 
ter referred to as “cod”) in net pens 
