Simulated production losses in reindeer herds caused by accidental death of animals

Abstract

A dynamic age-structured model was used to simulate the consequences on herd production if an extra animal from a particular age class and season was lost. Herd size was adjusted to 1000 animals and a sex ratio of .75/.25 via slaughter in late autumn. Three harvest strategies were applied, ranging from extreme calf to adult harvest. Equilibrium herd structure was disturbed with the loss of an extra animal and the consequences in terms of the number of animals slaughtered and kilogram of carcasses produced were followed over a simulation period of 15 years. The loss of a male corresponded largely to 0.70 to 0.90 times its own carcass weight. Loss of a female decreased herd production by 1.2 to 1.7 times the carcass weight of the lost animal. The highest losses were observed for 4-6 year old females. Loss of a calf reduced herd production by 0.3 to 1.6 times the calf's carcass weight, depending on season of loss and harvest strategy. In general, a loss during winter decreased herd production 10 to 20 percent more than a loss during autumn.