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Fishery Bulletin 106(4) 
Figure 4 
Vitamin A1 rhodopsin absorbance templates (Stavenga et al., 1993) fitted to Pacific hali- 
but (Hippoglossus stenolepis ) electroretinogram (ERG) data by the maximum likelihood 
method. The circles show the normalized spectral sensitivity data and the solid lines 
show the predicated combined photopigment absorption curves. The predicted individual 
photopigment absorption curves for the short and long wavelength pigments are shown 
the by the dotted and dashed lines, respectively. The predicted absorption maxima are 
in reasonable agreement with family Pleuronectidae (Evans et al., 1993; Jokela-Maatta 
et al,. 2007). Note the dramatically diminished importance of the longer wavelength pig- 
ment in halibut exposed to 15 minutes of simulated sunlight, especially at night. The 
spectral colors corresponding to the various wavelengths are shown in Figure 3. 
Discussion 
Our observations with black rockfish do not support 
our original contention that exophthalmia and other 
internal events associated with rapid decompression 
compromise retinal function. We found no differences in 
light sensitivity (V-log I response curves), flicker fusion 
frequency, or spectral sensitivity between control and 
experimental fish. Our procedures would not, however, 
detect damage to the optic nerve or other parts of the 
central nervous system associated with vision. Experi- 
ments involving visually evoked potentials (Bullock et 
al., 1991), predator- and prey-sighting distance, the 
optomotor response, or other behavioral procedures 
(Douglas and Hawryshyn, 1990; Vogel and Beauchamp, 
1999; Herbert and Wells, 2002) are needed to confirm 
the lack of detrimental effects of barotrauma on visual 
function in black rockfish. Rockfish simply discarded on 
the surface after being subjected to rapid decompression 
during capture frequently float. They are than subjected 
to high rates of avian predation. Returning rockfish to 
depth (repressurization) reverses the external signs 
of barotrauma (Parker et al., 2006). Our observations 
confirm that releasing rockfish at depth is an effective 
procedure for minimizing postrelease mortality, except 
for fish with severe hook injuries (St. John and Syers, 
2005). 
In contrast to the apparent lack of effects of baro- 
trauma on vision in black rockfish, there are multiple 
lines of evidence that 15 minutes of exposure to simu- 
lated sunlight dramatically affects the visual func- 
tion of Pacific halibut. First, exposure to bright light 
causes a large reduction in sensitivity (Table 1) indi- 
cated by the approximate 3 to 7x increase in amount 
of light required to achieve an ERG response to broad 
spectrum white light that is 50% of the maximal re- 
sponse (Table 1). We strongly suspect that low-light 
vision was also affected. Measuring low-light sensitiv- 
ity (i.e., minimal detectable ERG response) requires a 
specific set of procedures different from the ones we 
employed (Reilly and Thompson, 2007) and we did not 
have sufficient support for this project to allow us to 
