Beaked whale heads: is there a smoking sonar?

Over 20 beaked whales died in mass strandings within the last two years. Three strandings (Bahamas, Madeira, and the Canary Islands) coincided with large scale naval exercises, raising concerns for blast and acoustic traumas. This talk focuses on the analyses of theBahamian and Madeiran events; however, because final consensus reports are not yet available, the analyses presented are not binding nor definitive. Tissues and intact heads were examined from 9 of 15 animals, 5 of which were adequately fresh condition to warrant CT and histologic examination. No animal had conventional blast damage, but all heads had evidence of in vivo cranial trauma: intra-cochlear blood, subarachnoid hemorrhages, and ventricular clots. The hemorrhage patterns suggests inner ear structures remained intact andthe cochlear aqueduct was the conduit for bloodflow between cranial and inner ear spaces. These pathologies may have compromised hearing but were unlikely to be immediately lethal. The following etiologies have similar trauma patterns: concussive acoustic trauma,barotrauma, auditory concussion, sonic booms, spontaneous hemorrhage and hyperemia, vestibular atelactasis, intraoperative birth trauma, and diathetic disease. Of these, a direct acoustic pressure event or diathethic stress response are most consistent with the stranding event and postmortem evidence.