Estimation of offspring production from a limited number of stage-structured censuses

We propose a procedure for maximum likelihood estimation of the number of a nimals or offspring in a closed population where the individuals counted go through stages or age-groups. Application of the procedure requires knowle dge of the distributions of the stage durations. A procedure for maximum li kelihood estimation of those based on marked animals is also given. The pro cedures are illustrated by applying them to gray seal (Halichoerus grypus) data from Froan Nature Reserve, Central Norway, from the breeding seasons 1 990-1999.