Assessing seal carcasses potentially subjected to grey seal predation

• Published in: Scientific Reports
• Main Authors: van Neer, Abbo, Gross, Stephanie, Kesselring, Tina, Grilo, Miguel L., Ludes-Wehrmeister, Eva, Roncon, Giulia, Siebert, Ursula
• Other Authors: Ministry of Energy, Agriculture, the Environment, Nature and Digitalization of Schleswig-Holstein, Germany, Projekt DEAL
• Format: Article in Journal/Newspaper
• Language: English
• Published: Springer Science and Business Media LLC 2021
• Subjects: Multidisciplinary; Phoca vitulina
• Online Access: http://dx.doi.org/10.1038/s41598-020-80737-9; http://www.nature.com/articles/s41598-020-80737-9.pdf; http://www.nature.com/articles/s41598-020-80737-9

Abstract In order to conduct an objective evaluation of potential ecological effects of grey seal predation on marine mammals, it is essential to establish a broad knowledge base helping in the thorough identification of such cases during post-mortem examination. The aim of this work is to report and discuss outcomes resulting from a retrospective evaluation of harbour ( Phoca vitulina ) and grey seal ( Halichoerus grypus ) stranding and necropsy data (n = 3274). In addition, the results are compared to a recent case of definite grey seal predation from Germany as well as reports from other countries. Carcasses potentially subjected to grey seal predation show severe lacerations with a circular pattern leaving a smooth, linear and cut-like wound margin. Large parts of skin and underlying tissue are detached from the body and loss of blubber is common. Occurrence frequencies of encountered lesions are presented and a list of parameters to be used for the assessment of similar cases as well as a complementary decision tree are suggested. With the proposed parameters, categories and tools, a baseline can be built in order to facilitate the standardised recognition of predation cases during post-mortem examinations of seals between groups working with populations across several geographic ranges.