574 
Fishery Bulletin 115(4) 
sitivity in Pacific halibut across a broad range of illu¬ 
minations, and the -94% reduction in light sensitivity 
does not recover for during 10 weeks. Visual sensitivity 
appeared to be most affected at low ambient light lev¬ 
els. If this impairment is permanent, we speculate that 
fish may either make the best of a bad situation if they 
are released into deep waters, or attempt to move to 
shallower water to compensate for their visual deficit. 
However, these conclusions from our ERG data conflict 
with our behavioral data and observations, where no 
clear impairment in simulated prey detection was ob¬ 
served. We suspect that our behavioral assay may not 
have been ideally designed to show differences in vi¬ 
sual sensitivity. We are not aware of any other studies 
that have attempted to link visual function, as mea¬ 
sured by methods such as ERG, with behavioral per¬ 
formance, which ultimately determines the fitness of a 
species with visual deficits. This is an area of research 
that will be needed to assess the consequences of dam¬ 
age to the visual system resulting from conditions on¬ 
board vessels before discard of bycatch (Pacific halibut 
and other fish species), and to assess the implications 
of such damage for fisheries management. 
Acknowledgments 
We thank P. Iseri, M. Ottmar, and S. Haines for assis¬ 
tance with the collection, care, and husbandry of fish. 
We also wish to acknowledge 3 anonymous reviewers 
for their insightful comments and editorial assistance 
on an early version of the manuscript. 
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