off-shore drilling, human movements, unidentified machinery, tugs, and other marine service craft. The recordings, made in winter, spring, and fall, were obtained from under the ice, or from leads, polynyas, or open water at distances from a.few meters to about 185 km from the source. Estimated overall source levels varied from 40 to over 200 dB re 1 /xPa at 1 m, in the effective bandwidths. Principal acoustic energy occurred in bands falling between 10 Hz and 13 kHz. Among the lowest levels encountered were those from the sounds of oil exploration drilling. The highest were from seismic profiling. Durations of man-made sounds varied from msec (metallic impulses) to continuous (line spectra from engines). In terms of frequency (Hz) The presence and behavior of bowhead whales near offshore oil and gas exploration activities in the eastern Beaufort Sea were studied during August 1980.'Numerous bowheads were within 5 km of an artificial island construction site where a large dredge, a barge camp, and several boats were operating. In a different situation, the physical presence of a 16.1-m boat had no apparent effect on the behavior of bowheads at a distance of 3.7 km. Subtle changes in behavior were noted when the vessel' s engines were idling with propellers disengaged. Bowheads within 1 km of vessels responded by spending briefer periods at the surface, by respiring fewer times per surfacing, and by moving away from the disturbance. Surfacing and breathing patterns returned to normal following the disturbance, while interanimal distances remained greater. Whales 13 km from an underwater seismic exploration operation did not behave differently from animals in the same area on days preceding and following the seismic work. In 1969 an underwater test facility was constructed specifically to study the biological effects produced by underwater blast. Investigations were conducted to determine the ranges from explosive charges, up to 3.6 kg, that were safe, damaging, or lethal to selected species of fish, birds, and mammals. It was established that the impulse (integral pdt) in the underwater blast wave was the parameter that governed biological damage and not peak pressure or energy. There was good correlation between the impulse and body weight in fish that ranged from 12 pKa.ms for 0.02-g guppy fry to 341 kPa-ms for 744-g carp. The blast response of fish with ducted swim bladders was the same as fish having nonducted swim bladders. Mallard ducks were selected as a model to represent birds on and beneath the water surface. Impulse levels-that were safe, injurious, or lethal to birds were determined and presented as a function of range and charge weight. The tolerance of six mammalian species, that ranged in body weight from 0.2-45 kg, was investigated. A tentative interspecies extrapolation, relating impulse to body weight, was illustrated as a method that may be pursued to predict the response of large marine mammals to underwater blast. A safe-impulse criterion of 14 pKa.ms for personnel was evaluated by an unprot...
