Diseases and causes of mortality among sea turtles stranded in the Canary Islands, Spain (1998-2001)

Abstract

This paper lists the pathological findings and causes of mortality of 93 sea turtles (88 Caretta caretta, 3 Chelonia mydas, and 2 Dermochelys coriacea) stranded on the coasts of the Canary Islands between January 1998 and December 2001. Of these, 25 (26.88%) had died of spontaneous diseases including different types of pneumonia, hepatitis, meningitis, septicemic processes and neoplasm. However, 65 turtles (69.89%) had died from lesions associated with human activities such as boat-strike injuries (23.66%), entanglement in derelict fishing nets (24.73%), ingestion of hooks and monofilament lines (19.35%), and crude oil ingestion (2.15%). Traumatic ulcerative skin lesions were the most common gross lesions, occurring in 39.78% of turtles examined, and being associated with Aeromonas hydrophila, Vibrio alginolyticus and Staphylococcus spp. infections. Pulmonary edema (15.05%), granulomatous pneumonia (12.90%) and exudative bronchopneumonia (7.53%) were the most frequently detected respiratory lesions. Different histological types of nephritis included chronic interstitial nephritis, granulomatous nephritis and perinephric abscesses, affecting 13 turtles (13.98%). Ulcerative and fibrinous esophagitis and traumatic esophageal perforation were the most frequently observed lesions in the esophagus, being associated in the majority of the cases with ingestion of fishing hooks. Larval nematodes of the Anisakidae family caused gastritis in 15 turtles (16.13%). Necrotizing and/or granulomatous hepatitis were the lesions most commonly observed in the liver (27.95%). Traumatic lesions included necrotizing myositis (10.75%) mainly caused by entanglement in fishing nets or boat-strikes, and amputation of 1 or 2 flippers (25.81%) by netting. Traumatic erosions and/or fractures of the carapace/plastron mainly caused by boat-strikes were also observed (26.88%). Eye lesions included heterophilic keratoconjunctivitis, ulcerative keratitis and heterophilic scleritis, affecting 7 turtles (7.53%).