PROJECTS

The behavioral response of marine mammals to Navy sonar exposure has been a research area funded by the U.S. Navy for around two decades. In 2015 the Office of Naval Research, Living Marine Resources, and the National Oceanic and Atmospheric Administration (NOAA) funded the first Behavioral Response Research Evaluation Workshop (BRREW) project, which reviewed the state of knowledge on marine mammal behavioral response to sonar at that time. The goals were to evaluate the return on investment of U.S. Navy funded programs, identify the data needs and the contributions of current research programs to meeting those needs, and evaluate the ability to meet outstanding data needs given the current state of technology. Results appeared as a report (Harris & Thomas 2015) and a review paper (Harris et al. 2018). Harris & Thomas (2015) recommended that “Behavioural Response Study (BRS) research be continued and extended to increase sample sizes and experimental replication, and temporal duration and spatial scale. It was noted that future investigations would benefit from combining experimentation and observation to enable linkage of short-term behavioral response to long-term fitness consequences of repeated exposure. The importance of baseline studies and longer-term monitoring of animals beforeand after exposure is emphasized throughout.” (Harris & Thomas 2015). Many of these recommendations were acted upon in subsequently-funded BRS efforts.

Nine years later, and with substantial continued investment by the Navy, ONR funded a follow-on review with a focus on documenting and synthesizing all available BRS data across research programs, the questions that have been addressed through BRS research, and the analysis methods used (BRRR project). This effort was completed at the end of 2024.

The outcome of the BRRR project is two linked databases (an Exposure database documenting the experiments and observations performed and a Question database documenting the scientific questions addressed) and a reference library. The Exposures and Questions databases include data from 111 and 101 publication/report documents, respectively. The Exposure database contains 3416 entries, including more than 4100 sonar exposure events and 28 species. The Questions database contains 315 entries relating to discrete analyses that have been conducted on exposure data.

This current project will build on the findings of the BRRR project and will use the resulting database resources to help the Navy understand the data available to meet Navy needs, identify across-species, across-context findings and lessons, and prioritize future BRS efforts. It is intended as preparation for a workshop to be held in spring 2026 (under separate funding). In helping focus that workshop, Navy stakeholders will be asked to identify key needs for environmental compliance relating to Navy training and testing activities. A synthesis of available data and an associated gap analysis will be conducted for each identified need and will form part of a pre-workshop reading pack.