The Lamont-Doherty Earth Observatory (LDEO) requires that vessel operations employing acoustic (seismic) sources adhere to a strict set of procedures designed to minimize interactions between the sources and marine mammals. Recognizing that different species of marine mammals may be sensitive to different sound frequencies and decibel levels, the researchers are seeking to better understand how strongly and how far sound pulses travel, both in shallow and deep water. Below is a brief summary of LDEO's "Marine Mammal Protection Procedures:"
- the LDEO Marine Science Coordinator obtains detailed schedules of proposed research activities and routes, and specifications of the equipment to be deployed
- knowledge of mammal activities known to the area is established and research is scheduled to avoid significant seasonal events such as migration, breeding, and calving
- An Environmental Assessment is written and permit is applied for
- trained marine mammal observers are appointed
(to be applied according to geographical area and need as determined by the National Marine Fisheries Service permit requirements)
- Before the seismic array is deployed marine mammal observers deploy a hydrophone streamer for detecting and monitoring marine mammals acoustics
- the vessel observes an established safety zone for marine mammals appropriate to the type of acoustic activity to be conducted
- the marine mammal observer ensures that no mammals are within the zone for at least one half hour prior to seismic operations
- the sound source is initially activated at the lowest possible source levels and increased at a prescribed rate (not to exceed 6 dB per 5 minutes) to allow marine mammals in the vicinity to detect, track, and avoid the sound
- all marine mammal sightings are reported; details regarding the sighting (e.g. species, time, activities, number of individuals, location with reference to the vessel) are reported on the official sighting form and database
- when a designated mammal (or mammals) is observed to be within or about to enter the safety zone, the sound sources are to be deactivated immediately; once the mammals are clear of the zone the sound sources can be activated at the lowest source levels and slowly increased to prescribed rates.