Long term passive acoustic monitoring of the distribution and movement patterns of North Atlantic right whales (Eubalaena glacialis) in Stellwagen Bank National Marine Sanctuary

Abstract

The North Atlantic right whale (Eubalaena glacialis) is considered the most endangered large whale species as a result of historic whaling, modern ship collisions, and fishing entanglements. To monitor the distribution and movement patterns of the right whales within Stellwagen Bank National Marine Sanctuary (SBNMS), a critical feeding area at the mouth of the Massachusetts Bay, passive acoustic techniques were used. Passive acoustic recordings were made at between 7 and 9 locations throughout the SBNMS from January to May 2006, July to December 2006, and January to February 2007 (366 days). Recordings were made using Automated Recording Units (ARUs), produced by Cornell University, recording at frequencies between 0 and 1000 hertz. Right whale up-calls, a type of vocalization, are the dominant call type occurring within the study area. An automated detection program (Urazghildiiev and Clark 2006) detected over 22,522 up-calls in 89,280 hours of data. Up-calls were present throughout the sanctuary for 11 out of the 13 months, and were present throughout the 24 hour cycle, with a pronounced peak in activity in the late evening. These results show that right whales use the sanctuary to a greater extent than previously thought, particularly during the winter months. The Right Whale Sightings Advisory System (RWSAS) includes visual sightings of right whales from a variety of platforms. During the 366 recording days the RWSAS had 33 sightings of 311 right whales that could have fallen within the acoustic range (8 nautical miles radius) of the ARUs. Sightings from the RWSAS did not account for all the acoustic 2 behavior present throughout the sanctuary. These results suggest that passive acoustics is an effective tool for monitoring right whale activity and distribution, and can significantly augment management efficacy during months when other techniques are severely limited. The present results will help to direct further management decisions towards reducing ship-whale collisions and fishing entanglements with the right whales.