Disputas: Dinara Sadykova

Prøveforelesning

Bedømmelseskomité

Docent Cibele Q. da Silva, Universidade de Brasilia, Instituto de Ciencias Exatas, Dept. de Estatistica, Campus Universitario, Brasil
Professor Hans Julius Skaug, Matematisk institutt, Universitetet i Bergen
Professor Tom Andersen

Leder av disputas:  Professor Trond Schumacher

Veileder:  Tore Schweder, Geir Storvik og Nils Christian Stenseth

Sammendrag

Management is more successful when based on more complete information. An understanding and quantification of the associated uncertainties is essential for successful management. The manager is often faced with more or less independent datasets of different types. These data need to be integrated to provide picture, as complete as possible, to the decision-makers. Integrated analysis, to which this work is a contribution, is a statistical methodology that allows extracting the combined information from diverse data considered to be relevant. The main objective of this PhD work was to expand methods for integration of diverse data by population dynamics models using non-Bayesian methods based on likelihood functions, and to apply the methodology to two biological systems: the bowhead whale in the Bering-Chukchi-Beaufort Seas (the BCB bowhead), and the crayfish in Lake Steinsfjorden in southern Norway. Our work shows that the method, which was developed for the bowhead whale application, makes better use of the available data than existing methods, and continued photographic surveying is found sufficient in the long run. Our work, which was carried out for the crayfish application, suggests that the main driver of decline in the crayfish population was due to density-dependant effect of the Elodea expansion (Elodea is a water weed covering up places the crayfish can hide during molting) with reduced number of hides and thus increased risk for predation and cannibalism, but also that temperature played an important role related to recruitment. It was found that a change in the legal size limits had been sufficient to prevent the crayfish population from decline after 1987, without any change in number of crayfish harvested.

Subject areas are statistics, biology and management.

The study had been carried out at the Centre for Ecological and Evolutionary Synthesis (CEES), Biological Department, University of Oslo

Kontaktperson

For mer informasjon, kontakt Gry Slettner Windsland.