Pacific Coastal & Marine Science Center
Coastal and Marine Earthquake Studies
|SHIPS: Seismic Hazards Investigation in Puget Sound
Preliminary Results of SHIPS Marine Mammal Injury Mitigation
MARINE MAMMAL MITIGATION AND RESEARCH
The marine mammal research and mitigation was conducted successfully during the US Geological Survey seismic exploration program SHIPS (Seismic Hazards Investigations in Puget Sound). This research was conducted by numerous researchers primarily with Cascadia Research, under contract to the USGS.
Mitigation efforts were successful in reducing the risk of injuries to marine mammals. On three occasions shut-down of the airguns was requested and immediately implemented in response to marine mammals being sighted near the vessel. On two additional occasions the airgun operations were voluntarily suspended by USGS as an added precaution while transiting areas of high densities of marine mammals or presence of gray whales. The survey route was also modified on several occasions to avoid areas of high marine mammal densities.
Research on the reaction of marine mammals to the airguns was also conducted successfully throughout the surveys. This should provide valuable new information on both how and at what distance marine mammals react to airguns. Research components included:
The study was lucky to have extremely good weather conditions through most of the study. More marine mammals were seen during both the vessel and the aerial surveys than had been anticipated including: Harbor seals were the most abundant marine mammal seen with highest concentrations in Puget Sound. More than 300 sightings of harbor seals were made during the aerial surveys alone. California and Steller sea lions were seen in high numbers in several areas including Puget Sound Elephant seals are an occasional visitor to these waters and only a few were seen in the Strait of Juan de Fuca Harbor porpoise were seen primarily in the Strait of Juan de Fuca and around the San Juan Islands. Dall's porpoise were encountered in both Puget Sound and the Strait of Juan de Fuca. Gray whales were seen in two areas. Around Whidbey Island, a number of gray whales were seen feeding. These represented early arrivals of the "summer-resident" population of gray whales that annually feed in these waters. Several of these have already been individually identified and include two whales that have come to these waters for six or more years. At the western entrance to the Strait of Juan de Fuca, offshore of where the seismic surveys were conducted, gray whales were also seen along their normal migratory pathway. Minke whales were seen on several occasions in the Strait of Juan de Fuca. This species had been thought to be not as common this time of years as in the summer when most sightings are made. Data gathered for the marine mammal research will be compiled and analyzed over the next four months and a final report prepared at that time.