The applied research discussed in detail in this report supplements the work performed during the 1983 southbound and northbound migrations of the gray whale, Eschrichtius robustus, in the Monterey, California region. The objective of both phases has been to determine the degree of behavioral response of migrating gray whales to acoustic stimuli associated with oil and gas exploration and development activities. The results of that earlier work were presented in Bolt Beranek and Newman Inc. Report No. 5366* This companion document extends the 1983 research effort, adding to the statistical data base through measurements of behavioral response of the January 1984 southbound gray whale population to the same acoustic stimuli used in 1983 and to the operation of a single air gun. The playback sounds consisted of tape recordings of underwater acoustic signatures of a drilling platform, drillship, production plat-. form, semisubmersible drilling rig and a helicopter overflight. Analysis and interpretation of the resulting 1984 data both support and strengthen the findings of the 1983 research effort.