A review of big data analysis methods for baleen whale passive acoustic monitoring

Many organizations collect large passive acoustic monitoring (PAM) data sets that need to be efficiently and reliably analyzed. To determine appropriate methods for effective analysis of big PAM data sets, we undertook a literature review of baleen whale PAM analysis methods. Methodologies from 166 studies (published between 2000–2019) were summarized, and a detailed review was performed on the 94 studies that recorded more than 1,000 hr of acoustic data (“big data”). Analysis techniques for extracting baleen whale information from PAM data sets varied depending on the research observed. A spectrum of methodologies was used and ranged from manual analysis of all acoustic data by human experts to completely automated techniques with no manual validation. Based on this assessment, recommendations are provided to encourage robust research methods that are comparable across studies and sectors, achievable across research groups, and consistent with previous work. These include using automated techniques when possible to increase efficiency and repeatability, supplementing automation with manual review to calculate automated detector performance, and increasing consistency in terminology and presentation of results. This work can be used to facilitate discussion for minimum standards and best practices to be implemented in the field of marine mammal PAM.     

Visual and acoustic surveys for North Atlantic right whales,Eubalaena glacialis,in Cape Cod Bay,Massachusetts, 2001–2005: Management implications

North Atlantic right whales, Eubalaena glacialis, remain endangered, primarily due to excessive anthropogenic mortality. Current management protocols in US waters are triggered by identifying the presence of at least one right whale in a management area. We assessed whether acoustic detection of right whale contact calls can work as an alternative to visual aerial surveys for establishing their presence. Aerial survey and acoustic monitoring were conducted in Cape Cod Bay, Massachusetts, in 2001–2005 and used to evaluate and compare right whale detections. Over the 58 d with simultaneous aerial and acoustic coverage, aerial surveys saw whales on approximately two-thirds of the days during which acoustic monitoring heard whales. There was no strong relationship between numbers of whales seen during aerial surveys and numbers of contact calls detected on survey days. Results indicate acoustic monitoring is a more reliable mechanism than aerial survey for detecting right whales. Because simple detection is sufficient to trigger current management protocols, continuous, autonomous acoustic monitoring provides information of immediate management utility more reliably than aerial surveillance. Aerial surveys are still required to provide data for estimating population parameters and for visually assessing the frequency and severity of injuries from shipping and fishing and detecting injured and entangled right whales.