Principal Investigator: Melissa Soldevilla and Lance Garrison (Southeast Fisheries Science Center)
Co-Principal Investigators:
External Collaborator:


Project title

Analyzing passive acoustic recordings from potential Bryde's whale habitat and characterizing ocean noise in the Northern Gulf of Mexico

Background

Bryde’s whales, which are the only year-round resident baleen whale in the Gulf of Mexico, currently have an estimated abundance of 33 whales and are undergoing a status review by NMFS to determine if an Endangered Species Act listing is warranted. Sightings of Gulf of Mexico Bryde’s whales are rare, and it is unknown whether or not they still occupy their historical habitat range. Use of autonomous passive acoustic methods are the best tool for finding rare whale species where they occur infrequently and where they have been historically sighted. Human activities such as oil and gas exploration and extraction, fisheries, and shipping in the Gulf of Mexico could pose additional risk to this already small population, and this project will help better understand their distribution and ecology.


Sightings map
 

Research Objectives

The purpose of this study is to analyze data from five autonomous acoustic recording packages (ARPs; Wiggins and Hildebrand, 2007) deployed for one year in an area of historical importance to this small population of resident baleen whales to 1) determine if they occur in waters beyond the northeastern Gulf of Mexico; 2) evaluate the seasonal occurrence and site fidelity at western Gulf sites; and 3) characterize ambient noise conditions in this region of high shipping and seismic activity. We will use a combination of manual and automated methods to detect Bryde’s whale calls in continuous recordings from 5 calibrated ARPs deployed from June 2016 to June 2017 along the 200 m isobaths throughout the western Gulf of Mexico predicted Bryde’s whale habitat (Figure 1). If Bryde’s whale calls are found in any of the recordings, these will be evaluated for seasonality and compared with seasonal occurrence patterns from the northeastern Gulf habitat. An additional goal is to characterize the ambient sound environment from the calibrated recordings at these sites to determine whether acute or chronic anthropogenic noise sources pose a risk to this species. Given the small population size and unique genetic lineage of this stock of Bryde’s whales, it is imperative that we determine the extent of their range, seasonality of their distribution, and what noise conditions occur throughout their habitat in order to offer the best protection possible should this stock be listed under the ESA.


                           Bryde's whale

Significance

This project aims to improve NMFS understanding and management of 1) marine species’ biology through the use of acoustic techniques and 2) ocean soundscapes and their natural and anthropogenic components, including characterizing levels and trends in ocean noise. Specifically, it aims to expand our understanding of the current distribution of a rare population of Bryde’s whales in the northern Gulf of Mexico by evaluating data from acoustic recorders deployed in their historical habitat range to determine if whales still occupy this region. It is unknown whether the high density of oil and gas exploration and extraction, fishing effort, and shipping traffic in the northwestern Gulf has led to a reduction in number of whales found in this habitat. Autonomous passive acoustic monitoring is the most successful tool for finding acoustically active whales in low density regions of their habitat and has been useful for identifying critical habitat of North Pacific right whales. A recent NRDC petition requests that this stock of Bryde’s whales be listed as endangered and that critical habitat be designated, and NMFS is currently conducting a status review. Analysis of fixed passive acoustic instrument data collected in the predicted habitat region will provide information to determine whether this is an important area as well as where and how frequently Bryde’s whales occupy this region. Additionally we will be able to characterize natural and anthropogenic ambient noise at these stations using recordings from the calibrated instrumentation which can be compared with data collected under the ONRSN project, thereby enhancing the value of both projects.