Poor visibility definition
Poor visibility means any conditions under which the estimated distance at which a gray whale can be reliably sighted is less than the defined exclusion radius. A prohibition on night shooting could increase the survey duration by up to 50%, which would be undesirable, both in terms of increased costs and in terms of extending the duration of the seismic survey into the period of peak whale abundance. The Workshop therefore agreed that night shooting or shooting during fog or poor light should only be conducted when the line has been surveyed (either by a separate “scout” vessel or while shooting an adjacent line) in good conditions during the preceding six hours and no gray whales have been sighted within this period. This would be the first time such a measure has been tried: the period of 6 hours, while considered practical to implement, remains, in the absence an analysis of the effectiveness of the measure for different choices of period, arbitrary.
Poor visibility means any conditions under which the estimated distance at which a gray whale can be reliably sighted is less than the defined exclusion zone.