Atypical beaked whale mass stranding in Almeria´s coasts: pathological study

Abstract

A pathological study was carried out in beaked whales (BWs) massively stranded in the coast of Almería (Southeast Spain) on January 2006. This work has provided new data about the relationship between naval exercises and the stranding and death of marine mammals. Two animals stranded alive on 26th and other two were founded dead on 27th. Four Cuvier’s BWs (Ziphius cavirostris), two juvenile females and two adult males were examined postmortem and studied histopathologically, three of the four animals were in a very fresh state. All animals were in a good body condition, no inflammatory or neoplastic processes were noted, and no pathogens were identified. Macroscopically, whales had a severe venous gas embolism, diffuse congestion and haemorrhage, especially around the acoustic jaw fat, ears, brain, and kidneys. Gas bubble–associated lesions and fat embolism were observed in the vessels and parenchyma of vital organs. Severely injured whales died or became stranded and died due to cardiovascular collapse during beaching. Based on current scientific knowledge, and the pathological findings in this study, the most likely primary cause of this type of beaked whale mass stranding event is naval exercises, most probably anti-submarine active mid-frequency sonar used during the military naval exercises (Jepson et al. 2003, Fernandez et al. 2004, 2005, Cox et al. 2006). No official information about sonar activities has been released, but naval activities have been reported spatially and temporally related to that atypical beaked whale mass stranding.