Cutaneous conditions and injuries in Ziphius cavirostris and Mesoplodon peruvianus from Mexican Pacific and Southern California waters

Knowledge of health threats to beaked whales (Ziphiidae) in the Eastern Pacific Ocean is scarce. Images of 53 Ziphius cavirostris photo-identified around Guadalupe Island and in Southern California waters, and of a Mesoplodon peruvianus from the Mexican Central Pacific, all sighted in the period 2015-2021, were examined for miscellaneous cutaneous conditions and injuries. Off Guadalupe Island, half of the 50 individuals were re-sighted at least once, providing information on the evolution of conditions. In this cohort (including at least 10 females and 18 males), traumatic lesions (prevalence 100%) and diatom films (66.0%) were frequently observed. Cookie-cutter shark bite (CCSB) scars affected all individuals, indicating Z. cavirostris as a primary predation target, with a mean minimum rate of visible accumulation bites/year estimated at 0.56. Prevalence of linear scars was 100% in both sexes, but high density was observed only in males. CCSB and linear scars were also present in Z. cavirostris off California. Marks typical of a previous fisheries interaction were documented in one Z. cavirostris from Guadalupe Island showing body-encircling and transverse scars dorsally. Partial amputation of the dorsal fin in four whales was possibly due to predation or anthropogenic interactions. Three others presented circular, perforating lesions of dorsal fins, of unknown etiology. Pennella balaenopterae infested at least two Z. cavirostris. Orange-brown films of presumed diatoms were present in 33 whales from Guadalupe Island and in one individual from California. 'Tattoo skin disease-like' (TSD-like) lesions, 'focal skin disease' and 'pale skin patches' occurred in Z. cavirostris off Guadalupe Island and California. The M. peruvianus suffered a severe TSD-like condition. This study provides a first insight into the epidemiology of traumatic and non-traumatic skin conditions, including those of infectious, ectoparasitic, predator and anthropogenic origin, which may affect the health and welfare of some ziphiids in the Northeast Pacific.

Automated summary

Knowledge of health threats to beaked whales in the Eastern Pacific Ocean is limited. This study examined the skin conditions and injuries of Ziphius cavirostris and Mesoplodon peruvianus in the region. The results showed various traumatic and non-traumatic skin conditions, including traumatic lesions, diatom films, cookie-cutter shark bite scars, etc. The study also documented scars possibly related to fisheries interaction and partial fin amputation in some individuals. Circular, perforating lesions of dorsal fins of unknown etiology were observed as well. These findings provide valuable insights into the health and welfare of beaked whales in the Northeast Pacific.