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Siebert U, Pawliczka I, Benke H, von Vietinghoff V, Wolf P, Pilāts V, Kesselring T, Lehnert K, Prenger-Berninghoff E, Galatius A, Anker Kyhn L, Teilmann J, Hansen MS, Sonne C, Wohlsein P. Health assessment of harbour porpoises (PHOCOENA PHOCOENA) from Baltic area of Denmark, Germany, Poland and Latvia. Environ Int 2020; 143:105904. [PMID: 32615352 DOI: 10.1016/j.envint.2020.105904] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/05/2019] [Revised: 06/15/2020] [Accepted: 06/16/2020] [Indexed: 06/11/2023]
Abstract
Harbour porpoise (Phocoena phocoena), the only resident cetacean species of the Baltic Sea is formed of two subpopulations populations, occurring in the western Baltic, Belt Seas and Kattegat and the Baltic Proper, respectively. Harbour porpoises throughout these areas are exposed to a large number of human activities causing direct and indirect effects on individuals, that might also harm this species on a population level. From Latvia, Poland, Germany and Denmark 385 out of 1769 collected dead harbour porpoises were suitable for extensive necropsy. The animals were collected between 1990 and 2015 and were either by-caught or found dead on the coastline. Following necropsies, histopathological, microbiological, virological and parasitological investigations were conducted. Females and males were equally distributed among the 385 animals. Most animals from the different countries were juveniles between 3 months and 3 years old (varying between 46.5 and 100% of 385 animals per country). The respiratory tract had the highest number of morphological lesions, including lungworms in 25 to 58% and pneumonia in 21 to 58% of the investigated animals. Of those with pneumonia 8 to 33% were moderate or severe. The alimentary, hearing, and haematopoietic systems had inflammatory lesions and parasitic infections with limited health impact. 45.5 to 100% of the animals from the different countries were known by-caught individuals, of which 20 to 100% varying between countries had netmarks. Inflammatory lesions, especially in the respiratory tract were found in higher numbers when compared to control populations in areas with less human activities such as arctic waters. The high number of morphological changes in the respiratory tract and of bycatches especially among immature animals before reaching sexual maturity is of serious concern, as well as the low number of adult animals among the material. Data on health status and the causes of death are valuable for management. A next step in this regard will combine data from health and genetic investigations in order to detect differences between the two populations of the Baltic.
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Affiliation(s)
- U Siebert
- Institute for Terrestrial and Aquatic Wildlife Research, University of Veterinary Medicine Hannover, Foundation, Werftstr. 6, 25761 Büsum, Germany; Marine Mammal Research, Institute of Bioscience, Aarhus University, Frederiksborgvej 399, 4000 Roskilde, Denmark.
| | - I Pawliczka
- Prof. Krzysztof Skóra Hel Marine Station, Department of Oceanography and Geography, University of Gdansk, Morska 2, 84-150 Hel, Poland
| | - H Benke
- German Oceanographic Museum, Katharinenberg 14/20, 18347 Stralsund, Germany
| | - V von Vietinghoff
- German Oceanographic Museum, Katharinenberg 14/20, 18347 Stralsund, Germany
| | - P Wolf
- Landesveterinär- und Lebensmitteluntersuchungsamt Rostock, Thierfelder Str. 18, 18059 Rostock, Germany
| | - V Pilāts
- Nature Conservation Agency, Baznīcas iela 7, Sigulda LV-2150, Latvia
| | - T Kesselring
- Institute for Terrestrial and Aquatic Wildlife Research, University of Veterinary Medicine Hannover, Foundation, Werftstr. 6, 25761 Büsum, Germany
| | - K Lehnert
- Institute for Terrestrial and Aquatic Wildlife Research, University of Veterinary Medicine Hannover, Foundation, Werftstr. 6, 25761 Büsum, Germany
| | - E Prenger-Berninghoff
- Institute for Hygiene and Infectious Diseases of Animals, Justus Liebig University Giessen, Frankfurter Str. 85-87, 35392 Giessen, Germany
| | - A Galatius
- Marine Mammal Research, Institute of Bioscience, Aarhus University, Frederiksborgvej 399, 4000 Roskilde, Denmark
| | - L Anker Kyhn
- Marine Mammal Research, Institute of Bioscience, Aarhus University, Frederiksborgvej 399, 4000 Roskilde, Denmark
| | - J Teilmann
- Marine Mammal Research, Institute of Bioscience, Aarhus University, Frederiksborgvej 399, 4000 Roskilde, Denmark
| | - M S Hansen
- Section of Pathology, Department of Veterinary and Animal Sciences, University of Copenhagen, Ridebanevej 3, 1870 Frederiksberg C, Denmark
| | - C Sonne
- Marine Mammal Research, Institute of Bioscience, Aarhus University, Frederiksborgvej 399, 4000 Roskilde, Denmark
| | - P Wohlsein
- Department of Pathology, University of Veterinary Medicine Hannover, Foundation, Bünteweg 17, 30559 Hannover, Germany
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Abstract
All extant porpoise species show paedomorphic skeletal traits. These traits are hypothesized to be connected with rapid growth to reproductive size and could thus show geographic variation according to ecological circumstances. To investigate this, skeletal ontogeny was compared among harbour porpoises from California, West Greenland, the inner Danish waters, and the Sea of Azov. Porpoises from California grew to larger sizes than Danish porpoises, which were again larger than Greenlandic porpoises, whereas Azov porpoises were smallest. Size differences were largely attributable to differences in timing of offset of growth. Expression of paedomorphosis followed the same pattern among populations and sexes as adult sizes; Californian porpoises were less paedomorphic than the other populations across all assessed traits, whereas porpoises from Azov were the most paedomorphic. We propose that the larger size and less profound paedomorphism seen in Californian porpoises are attributable to fluctuation of prey availability, owing to variation in upwelling on which productivity in Californian waters depends. Skull shapes after correction for allometry were significantly different among all populations, Sea of Azov porpoises being most divergent. There was no overlap of skull shapes between the Atlantic, the Pacific, and Azov, supporting the current division of harbor porpoises ( Phocoena phocoena (L., 1758)) into three subspecies ( Phocoena phocoena phocoena (L., 1758), Phocoena phocoena relicta Abel, 1905, and Phocoena phocoena vomerina Gill, 1865).
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Affiliation(s)
- A. Galatius
- Department of Bioscience, Aarhus University, Frederiksborgvej 399, 4000 Roskilde, Denmark
- Research Group for Comparative Zoology, Institute of Biology, University of Copenhagen, Universitetsparken 15, DK-2100 Copenhagen O, Denmark
| | - P.E. Gol’din
- Department of Zoology, Taurida National University, Vernadsky Avenue, 4, Simferopol, 95007, AR Crimea, Ukraine
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