Read FL †*, Pierce GJ #, Kuiken T †*
† Department of Virology,
Erasmus Medical Centre, Rotterdam, The Netherlands
* Seal Rehabilitation and Research Centre, Pieterburen, The Netherlands.
# Department of Zoology, University of Aberdeen, Aberdeen, U.K.
Life history studies provide insight into the age structure of a population, age at sexual maturity, and life span. However, the life history of harbour seals (Phoca vitulina) is poorly known because of the inaccessibility of their habitat. Overall, the aim of this project is to establish a life history table for harbour seals in Dutch waters, using the uniquely large sample size from the 2002 phocine distemper epidemic. Analysis of 690 female and 612 male reproductive tracts allowed prediction of the standard length at which seals enter puberty (SLP) based on a non-linear regression broken stick model with one break. Onset of puberty in males was predicted using testis weight, baculum length and baculum weight. The predicted SLP for males was 110 to 113 cm, corresponding to a testis weight of 3.60 to 3.62 g, baculum length of 39.0 mm and baculum weight of 0.25 g. Onset of puberty in females was predicted using uterine horn diameter generating a predicted SLP of 107 to 108 cm, corresponding to a uterine horn diameter of 4.07 to 4.10 mm. Further analysis of the samples, including determination of age on the basis of growth layer groups in teeth, will be performed.
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