Marine Mammal Protection
The Lamont-Doherty Earth Observatory takes the responsibility of protecting marine mammals very seriously.
For fifteen years, The Research Vessel EWING was owned by the National Science Foundation and operated by the Lamont-Doherty Earth Observatory (LDEO) for use by academic researchers from universities around the world. It was outfitted to conduct acoustic research among other kinds of earth and environmental science. The Ewing has been replaced by R/V Marcus G. Langseth, which has enhanced seismic and other science capabilities.
In the course of conducting acoustic research, the Langseth operates an array of sound sources generated by compressed air (air guns) to map the structure of the Earth's crust on and below the sea floor. The maps generated allow a better understanding of how the planet functions from natural hazards to climate.
There is a paucity of data on how different sound levels radiate in different geographical surroundings, and how marine mammals may respond to these different levels. A report from The National Academies' National Research Council states that the "Impact of noise on marine mammals remains unclear." Funds should be designated for "research into how human-generated sounds may affect marine mammals," and "needed are better models to predict the noise levels that will be generated in the ocean by particular human activities."
The need for definitive data on the impact of human-made acoustic sources on marine mammals is of critical concern to the oceanographic community. Lamont is engaged in programs to further scientific understanding of marine mammal response to acoustic research, and is working with specialists in the field of marine mammals to help inform future researcher programs.
Standard operating procedure requires that research ships obtain permission to operate in national waters of any country, and US law requires compliance with the Marine Mammal Protection Act. A detailed environmental assessment statement is produced to determine that no significant danger will occur to the marine population. These US and foreign permits/permissions are sought over several months, simultaneously. The National Marine Fisheries Service, part of the National Oceanic and Atmospheric Administration, issues permits to vessels whose operations may "harass" marine mammals, an industry term describing any activity that alters a mammal's normal behavior. The Service issues guidelines as to the radius in which sound pulses might be received at various high decibel levels. These radii are calculated with computer models.
Prior to each expedition, knowledge of mammal activities known to the area is established so that research can be scheduled to avoid significant seasonal events, e.g. migration and calving. The ship in question observes an established safety zone for mammals appropriate to the type of seismic activity to be conducted, and in the event of a sighting, specific procedures are outlined to ramp down research so that mammals can safely move through the area. This monitoring of the safety radius includes the use of special high-powered binoculars, as well as towed sonar array used to listen for marine mammals. LDEO is recognized as a leader in the development and implementation of marine mammal mitigation.
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.