Introduction & Objectives

North Atlantic right whales (Eubalaena glacialis) migrate along the U.S. east coast between winter breeding grounds off Georgia and Florida, and summer feeding grounds off the northeastern U.S. and Canada. Intensive research and monitoring efforts are focused on both the feeding and breeding grounds of this highly endangered species, but very little is known about the movement patterns of right whales during migration. 

In fall 2013, we initiated a passive acoustic monitoring project to detect right whales migrating past Cape Hatteras, North Carolina, during their seasonal movements to and from Florida. The objectives of this project are to investigate the timing of right whale migration through the Mid-Atlantic region, as well as the relative distance from shore and acoustic behavior of migrating whales. This monitoring effort will help to fill a data gap in the central portion of the migratory corridor, and contribute to a broader understanding of the seasonal occurrence of right whales along the U.S. east coast.

Technical Approach

We are conducting passive acoustic monitoring using a linear array of marine autonomous recording units (MARUs), deployed on the continental shelf off Cape Hatteras, North Carolina, during right whale migratory periods. MARUs are bottom-mounted, archival recording instruments, capable of collecting continuous low-frequency acoustic recordings for up to six months at a time. The array consists of five MARUs, spaced 10 km apart in a line extending from shore out to the shelf break (200-m isobath). The MARUs are programmed to collect continuous acoustic recordings at a sample rate of 2 kHz for the full deployment period of 4-5 months for each season. Thus, to ensure full coverage of the entire right whale migratory period, we are replacing the first set of MARUs mid-way through the study period. After retrieval and data extraction, we will analyze acoustic recordings using an automated detection and classification system designed specifically for low-frequency baleen whale calls. In addition to North Atlantic right whales, we expect to detect the calls of humpback, fin, and minke whales on these recorders. We will involve undergraduate and graduate students at Duke University in analysis of these calls. Our analysis will include an evaluation of detector performance and an examination of temporal patterns in detected right whale calls.

Progress & Results

Four sets of MARUs have been deployed to date in October 2013 (Hatteras01), February 2014 (Hatteras02), October 2014 (Hatteras03), and March 2015 (Hatteras04).  As of  March 2016 all data for Hatteras01-03 deployments have been analyzed for NARW up-calls.  Up-calls were detected on 45 of 246 recording days from the Hatteras 01-02 deployments and 62 of 153 recording days in the Hatteras03 dataset. Analysis of the diel occurrence of detected up-calls showed an increase in calling activity during the late afternoon and evening hours. Additional details of the preliminary analysis of these data sets are available in the 2014 and 2015 technical progress reports. Analysis of the remaining Hatteras04 dataset was completed in 2016, and results from the entire project have been integrated into a broad-scale analysis of right whale occurrence along the U.S east coast led by researchers at NOAA NEFSC which is being prepared for publication.