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Age‐ and sex‐specific behaviour in harbour seals Phoca vitulina leads to biased estimates of vital population parameters by Tero Härkönen; Karin C. Hårding; Sven Gunnar Lunneryd is a Environmental Science article available to read on EtoBox.

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## Summary 1. Modelling of the population dynamics of seals require data on an array of vital parameters (fecundity, mortality, age structure, migrations, population growth rate). The most common way to obtain these data is to estimate the parameters from samples taken from the population. However, the influence from skewed samples can be substantial in populations with age‐ and sex‐specific features. By quantifying the behavioural differences among age and sex classes, data from skewed samples can be compensated retrospectively. Awareness of the existence and the potential magnitude of such biases is highly relevant for the design of surveys, sampling programmes and the implementation of management plans of age structured populations. 2. The age‐ and sex‐specific behaviour of harbour seals __Phoca vitulina__ and grey seals __Halichoerus grypus__ can be studied by using freeze‐branded animals. Since the brand is permanent and visible up to a distance of 500 m, the harassment is limited to one occasion in the lifetime of the seal (the catching day). 3. A method is also given for analysing data arising from re‐sighted branded animals, where re‐sightings of individual seals were trans

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Author

Tero Härkönen; Karin C. Hårding; Sven Gunnar Lunneryd

Publisher

John Wiley and Sons; Wiley (Blackwell Publishing); Blackwell Publishing Inc.; Wiley; JSTOR (ISSN 0021-8901)

Published

1999

Language

EN

Field

Environmental Science (Physical Sciences)