Skin Disorders of Coastal Dolphins at Añihué Reserve, Chilean Patagonia: a Matter of Concern

Abstract

Epidemiological characteristics and progression of skin disorders were documented in Peale's (Lagenorhynchus australis) and Chilean (Cephalorhynchus eutropia) dolphins resident in Añihué Reserve (43.8041ºS; 72.9786ºW) in Chile's Aysén Region. Since 2004, sea-pen based salmon farms began to surround the Reserve. We analyzed 5,734 frames in a graphic SQLite database obtained during systematic inshore monitoring of cetaceans in 2010-2013, comprising 115 photo-identified L. australis and several unidentified C. eutropia. In 2013, the prevalence of skin disorders peaked in L. australis at 81.7 %, an increase of 30.2 % versus 2011. Morbidity is unknown. Of six cutaneous conditions, 1-4 affected both species: (1) tattoo skin disease with 39.1 % prevalence in L. australis; (2) "pale skin patches", highly prevalent (74.8 %) in L. australis and characterized by opaque to translucent patches that expanded rapidly, then generally resolved within 10 days and occasionally recurred; (3) "focal skin diseases" were clusters of lesions of variable severity that affected all age categories with a 13.9% prevalence in L. australis and that led to deep cutaneous ulcers in a C. eutropia; (4) rare "skin lineal anomalies" (4 L. australis, 1 C. eutropia) of variable-length, dark, sometimes reticulated, that may persist for years; (5) a "necrotizing tissue mass" that grew rapidly in one L. australis over a preexisting injury for 40 days before scarring; (6) "ulcerative dermatitis (UDD)", a condition with hypodermal involvement seen in a cluster of 7 L. australis. Except for TSD, aetiologies of skin disorders remain unknown, however water pollution associated with the expanding salmon farm industry is suspected to have contributed to their emergence.