University of Natural Resources and Life Sciences, Vienna (BOKU) - Research portal

Logo BOKU Resarch Portal

Gewählte Master / Diploma Thesis:

Barbara Judith Laher (2012): "Altersbestimmung beim Europäischen Fischotter (Lutra lutra L. 1758) - Ein Methodenvergleich".
Master / Diploma Thesis - Institut für Wildbiologie und Jagdwirtschaft (IWJ), BOKU-Universität für Bodenkultur, pp 114. UB BOKU obvsg FullText

Data Source: ZID Abstracts
In the present thesis the age of 30 otter skulls and eight penis bones was determined by five different methods. Three methods divide the age into classes (determination of age by skull characteristics, by tooth abrasion and penis bone). Two methods determine the age by counting cement lines, which is an annual classification (determination of age by teeth thin sections with a cryostat and cutting machine). It was examined how these five methods differ in terms of age. By craniometry a total number of 39 sections of measurements were performed to divide the otter in juvenile and adult animals and confirm the sexual dimorphism. The statistical analysis showed no matching for the age class methods. The counting of cement zone agrees partly. The frozen thin-section age is not significantly different from the direct section age, which was evaluated with a microscope. There is no agreement with the direct section age, which was evaluated with a scanner image. The direct section age of the two different optical analyzes showed a relationship. The sexual dimorphism was confirmed by craniometry method. Gender distinctions regarding the proportions of the skull were found only for a ratio (length to mandible width). The division into juvenile and adult can be done with the craniometry and the penis bone. For this purpose there is a good agreement of 75%. The presented results are showing that in principle it is important to consider how exact the age has to be determined. With a sum of information obtained from the methods, the age is estimated well, but this is not an exact age determination. The frozen thin-section method is very expensive and costly in terms of time. That’s why it could be replaced by the direct section method. However, for this method further investigations should be done.

Beurteilende(r): Hackländer Klaus

© BOKU Wien Imprint