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Figure 7 
Probability of sighting an available group of harbor porpoise ( Phocoena phocoena) during the 
1997 aerial survey in Southeast Alaska by distance (km) from the survey trackline. Solid lines 
represent the probability of a sighting when both side observers and a belly observer were pres- 
ent. Thickness of the line (thick to thin) represents visibility codes excellent, good, fair, and poor. 
Dashed lines represent the probability of a sighting with only side observers (without a belly 
observer), where long to short dashes represent visibility codes excellent, good, fair, and poor. 
Figure 8 
Probability of sighting an available group of harbor porpoise ( Phocoena phocoena) during the 1998 
and 1999 aerial surveys in the Gulf of Alaska and Bering Sea, respectively by distance (km) from 
the survey trackline. Sighting distributions were sufficiently similar between the two years that 
a single curve was used for both. Solid lines represent the probability of a sighting when both 
side observers and a belly observer were present. Thickness of the line (thick to thin) represents 
visibility codes excellent, good, fair, and poor. Dashed lines represent the probability of a sighting 
with only side observers (without a belly observer), where long to short dashes represent visibility 
codes excellent, good, fair, and poor. 
