Evidence review
The accurate version is neither “sonar never matters” nor “sonar makes whales go crazy.” Evidence varies by species, signal, event, timing, pathology, and the quality of monitoring before and after an exercise.
Canary Islands · 2002
Fourteen beaked whales stranded near an international naval exercise. A peer-reviewed veterinary study reported gas bubble-associated lesions, fat embolism, congestion, and hemorrhage, and proposed mechanisms involving altered diving behavior and nitrogen supersaturation.
Read the study ↗Mariana Archipelago · 2007–2019
NOAA researchers found several beaked-whale strandings during or within six days of anti-submarine activities. One 2019 event was also near a training event, but the Navy confirmed sonar began after the stranding.
Read the study record ↗Current operations
Navy environmental documents describe visual and acoustic monitoring, shutdown procedures, geographic limits, biological-area review, and Marine Mammal Protection Act processes.
Review mitigation ↗Some mass strandings of beaked whales have occurred during or shortly after naval mid-frequency active sonar activity. Timing alone is not proof, but repeated co-occurrence is scientifically important.
Post-mortem studies have reported hemorrhage and gas/fat embolic lesions in affected beaked whales. Altered diving behavior and nitrogen dynamics are proposed mechanisms; the precise sequence is not universal or completely resolved.
The strength of evidence differs by event. Some investigations link naval activity and strandings; in others sonar is investigated and excluded by chronology or other evidence.
Deep-diving beaked whales appear unusually represented in well-known sonar-associated events. That does not mean every beaked-whale stranding is sonar-related or that all cetaceans respond identically.
Operational measures include visual and acoustic monitoring, shutdown or delay zones, geographic restrictions, environmental review, and biologically important areas.
Limits