Skin conditions, epizoa, ectoparasites and emaciation in cetaceans in the Strait of Gibraltar: An update for the period 2016-2020.

ABSTRACT: Cetacean populations in the Strait of Gibraltar are heavily impacted by human activities. Photographs a valuable tool to monitor external health cetaceans. We visually screened 27,866 pictures taken during whale watching operations years 2016–2020 for abnormal conditions, such as emaciation, dermal diseases and epizoic infestations. Prevalence levels could not be calculated data were obtained opportunistically. Dermal detected 566 sightings occurred all species. Bottlenose dolphins most strongly affected (n = 192). Hypopigmented skin lesions common species 291). Tattoo disease‐like 16 animals (T. truncatus: n 12; G. melas: 3; D. delphis: 1). Other observed conditions include expansive annular three juvenile pilot whales. Furthermore, we report presence open wounds 28 (G. 23; T. 2; P. macrocephalus: 3). In whales, these did heal over period several years. Epizoic ectoparasitic infestations observation Xenobalanus spp. Pennella balaenopterae. Multiple fin whales sighted with very high numbers balaenopterae, ranging up 84 parasites per host. Emaciation was mainly bottlenose 36) seemed affect more severely specific years, potentially indicating fluctuations prey availability. KEYWORDS: CETACEANS; DERMAL DISEASES; EMACIATION; ECTOPARASITES; STRAIT OF GIBRALTAR