[MARMAM] Two new publications on assessing seal and porpoise carcasses potentially predated by grey seals

van Neer, Abbo Abbo.van.Neer at tiho-hannover.de
Tue Jan 12 13:05:20 PST 2021


Dear MARMAM community,

on behalf of my co-authors, I’m very happy to finally share our two recent publications dealing with the assessment of wound patterns originating from grey seal predation.

Both publications suggest parameters frequently recorded in seal and porpoise carcasses and are regarded as typical for grey seal predation. In addition to the catalogue of parameters respective decision trees are suggested which can be used as a guide.

These suggested methods are considered as a start and will hopefully be kept up to date in a joint effort by all researchers working in the field and added to as new knowledge emerges.



Assessing seal carcasses potentially subjected to grey seal predation

van Neer, A., Gross, S., Kesselring, T., Grilo, M. L., Ludes-Wehrmeister, E., Roncon, G., & Siebert, U.

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.

https://doi.org/10.1038/s41598-020-80737-9


Assessing harbour porpoise carcasses potentially subjected to grey seal predation

van Neer, A., Gross, S., Kesselring, T., Grilo, M. L., Ludes-Wehrmeister, E., Roncon, G., & Siebert, U.

Abstract:
As a follow-up on the data presented for seals, we herein report and discuss outcomes resulting from a retrospective evaluation of harbour porpoise stranding and necropsy data from Schleswig–Holstein, Germany (n = 4463) to enable an objective evaluation of potential ecological effects of grey seal predation on porpoises. Results are compared to a recent case of definite grey seal predation as well as to reports from other countries. Porpoise carcasses potentially subject to grey seal predation show severe lacerations, with large parts of skin and underlying tissue being detached from the body. Loss of blubber tissue is common. Based on the occurrence frequencies of encountered lesions, a list of parameters as well as a complementary decision tree are suggested to be used for future assessments. The results shown add to an increasingly standardised assessment protocol of suspected grey seal predation cases making respective results comparable between different areas and countries. The usage of a standardised protocol may increase the awareness of grey seal predation and the reporting of such cases. By this, differences in the predation and feeding patterns as well as the potential ecological relevance of this behaviour may be elucidated.

https://doi.org/10.1038/s41598-020-73258-y




If you have any questions about these two publications, the methods described or any potential case you would like to discuss, please feel free to get in touch and I’ll be happy to help wherever I can.

Best regards

Abbo van Neer

___________________________________________________________________________________________________

Dr. Abbo van Neer
Institute for Terrestrial and Aquatic Wildlife Research (ITAW)
University of Veterinary Medicine Hannover, Foundation
Werftstr. 6
25761 Büsum
Germany

☏ +49  5 11 - 8 56 - 81 62
Fax: +49  5 11 - 8 56 - 81 81
abbo.van.neer at tiho-hannover.de<mailto:abbo.van.neer at tiho-hannover.de>
https://www.tiho-hannover.de/itaw


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