Age-specific harvest mortality in a Norwegian moose Alces alces population

The annual age- and sex-specific patterns of harvest mortality in a Norwegi an moose Alces alces population during a period of 17 years for females and 24 years for males were estimated using cohort analysis. In males the harv est mortality increased with age, whereas in females the pattern was U-shap ed with higher harvest mortality of less fecund young (1-3 year) and old (g reater than or equal to 10 years) age classes, and lower harvest mortality of prime age (4-9 years old) females. In both sexes, the calf harvest morta lity was low, although it increased with increasing calf quotas following a change from an indiscriminate to a sex- and age-specific hunting system du ring the study period. In adult males, the mortality pattern was opposite o f what was expected based on the previously reported higher susceptibility to hunting of young than old males, indicating that hunter selectivity for large (old) males affected the pattern. Moreover, the selectivity of the hu nters decreased as the hunting pressure increased, suggesting that the hunt ers became less selective when the mean time available per moose in the quo ta decreased. Among adult female age groups, the variation in harvest morta lity increased with the proportion of calves per female in the population p rior to hunting. This was mainly because of relatively higher mortality of post-prime females, supporting our expectation that hunters avoid shooting females with calves and thus increase the harvest of less fecund age groups during high recruitment years. The observed selectivity led to harvest mor tality that differed significantly from patterns of natural mortality, even where the mortality is mainly due to wolves Canis lupus and bears Ursus ar ctos. This may have consequences for the life history evolution of both mal e and female moose. The potential ecological, evolutionary and management i mplications of the results are discussed.