RIASSUNTO
Abstract
Marine mammals, including coastal dolphins, West African manatees, offshore cetaceans (baleen whales and larger odontocetes), and marine turtles are increasingly under threat; many are rare, although some cetaceans are showing recovery from commercial exploitation. When Angola Liquefied Natural Gas (LNG) began using Chevron's Operational Excellence Process for Environmental, Social and Health Impact Assessment (ESHIA) to manage the potential environmental impacts of a proposed LNG facility in the Congo River Basin, they collaborated with the Wildlife Conservation Society (WCS) to address issues identified in the Angola LNG ESHIA Process and to develop programs to protect the marine turtles and marine mammals through cooperative science and management, training, and education.
The Marine Mammal Program fieldwork, conducted by WCS and Angola LNG in the Congo River Basin area and South Atlantic coastline near Soyo, Angola, was completed between 2008 and 2009. Activities included the assessment of inshore and Congo River environments and marine mammals, and the use and deployment of Marine Autonomous Recording Units (MARUs; shown in Figure 1) as a cost-effective means of surveying whales in the South Atlantic Ocean. This was the first time MARUs were used off the coast of West Africa.
The MARUs allowed for long periods of continuous monitoring for vocalizing cetaceans, cetacean behavior and anthropogenic contributions to ocean ambient noise with relatively minor field effort. The technique also allowed for uninterrupted acoustic monitoring investigations, otherwise impossible with boat-based visual methods during night hours and inclement weather. However, there were certain challenges in using the MARUs, such as the analysis and management of large datasets, as well as the identification of signals in the recordings when there is little to no possibility of verifying all possible signals through simultaneous visual surveys and sightings. Due to logistical and safety limitations for conducting numerous offshore surveys for identification, existing data from other parts of the world were used for comparisons to confirm species of vocalizing whales. In many cases, some of the signals will remain unknown.