Population dynamics and life history of harbour seals : the determination of phocid vital rates using dental annuli and mark recapture
Estimates of survival were made in the Moray Firth to allow comparison with published estimates from other populations. Mark recapture analysis, using photographic identification of harbour seals between 1999 and 2002, estimated adult (age 2+) survival to be 0.965 (95% probability interval of 0.881-0.999). Estimated first year survival, made using a live census of the population between 1989 and 1992, was 0.39; a value lower than previously published estimates. However, survival in older age’s classes was comparable to published estimates from other areas, as is the estimate resulting from mark recapture analysis. In this thesis I use demographic models to explore the historical trends in harbour seal abundance in the Moray Firth. Following this, a combination of both new and established techniques are used to increase our understanding of vital rates for this population. The exact mechanism for decline in abundance post 1993 is not clear, but a large shift in adult survival post 1993 is not supported by the data in this thesis. However, inter-annual changes in food availability or quality, hunting, and increased emigration could all be influencing the vital rates, and thus the observed abundance of harbour seals in the Moray Firth.