We use cookies on our website. Some are necessary for the operation of the website. You can also allow cookies for statistical purposes. You can adjust the data protection settings or agree to all cookies directly.
Data Protection Declaration
Imprint
Investigation and assessment of any impacts of pingers (acoustic devices) on the hearing of porpoises in EU fisheries
Project
Project code: 2806HS010
Contract period: 01.07.2006
- 31.08.2010
Budget: 449,428 Euro
Purpose of research: Applied research
Following up the investigations of the BMVEL pilot project on morphology and histology of harbor porpoise (Phocoena phocoena) ears, the aim of this study was to investigate potential anthropogenic noise impacts. Echolocation is the main sense in harbor porpoises and important for detection of food, predator avoidance, navigation and communication. Therefore, it is likely that pathological changes in the ears cause impairment of auditory function which subsequently contribute to the etiology of by-catches and strandings.
42 ears from 21 harbor porpoises from the German and Danish North and Baltic Seas were EDTA decalcified, celloidin embedded and evaluated histologically for acoustic and other pathological changes after H & E staining. Data was compared with results from continuative microbiological, histological, serological, parasitological and virological investigations, as well as detailed necropsy data of the total carcass and of computed tomography of the ear region. Immunohistochemical and special staining techniques for the investigation of inflammatory and degenerative changes in a paraffin embedded ears have been tested.
17 porpoises were accidentally by-caught and died of acute heart and circulatory failure due to hypoxic shock after entanglement. 4 animals stranded and died due to a septic shock or severe encephalitis. General data on morphology of harbor porpoise ears was compiled and different pathological changes due to inflammation and trauma, as well as age related changes have been investigated. An atrophy of the organ of Corti was seen in two porpoises from the Elbe river, Gemany. 14 animals showed mild to severe hemorrhage in the basal parts of the scala tympani and some animals additionally in the scala vestibuli. A fracture with callus formation and bone sequestrum was found in an adult porpoise. Partly severe follicular hyperplasia was found in ears with verminous or fungal otitis media.
Fungal infections and severe nematode infestations may be associated with immunosuppression, which is associated with increased tissue concentrations of contaminants or antibiotics discharged into the sea. Furthermore, marine mammals are exposed to different acoustic insults, like pingers, boat noise, military sonar, blasting of ammunition or offshore windfarms. This report underlines the need for the ear to be investigated systematically in cetaceans in order to better understand impairment of the health status and hearing ability of marine mammals.
Section overview
Subjects
- Marine fisheries
