A STUDY OF ELAPHOSTRONGYLUS ALCES IN AN ISLAND MOOSE POPULATION WITH LOW CALF BODY WEIGHTS

Abstract

We studied prevalence of Elaphostrongylus alces (Protosyrongylidae; Nematoda), weights, mandible lengths, and mandible marrow fat in a moose population (Alces alces) at Utö in the Stockholm archipelago from October 1989 to November 1994. The moose population at Utö before culling was relatively dense (2.0/km²). Annual prevalence of infection with E. alces (adult worms, and/or eggs/larvae in the meninges) varied between 58% and 71%. The moose calves at Utö were smaller (mandible length 294±18 mm n = 73) and had lower processed carcass weights (45.4±10.4 kg n = 85), (bled, without viscera, skin, skill, and lower legs) than calves on the mainland. Low weights could not be statistically related to infection with E. alces, nor were there indications that low calf weights were related to lack of browse. However culling of moose calves and yearlings over a three year period results in a trend of reduced infection with E. alces. In a total of 2025 snails and slugs examined over 5 summers, 20 (1 %) were infected with elaphostrongyline larvae. Seven species (Arion subfuscus, Deroceras agreste, D. reticulatum, Limax cinereoniger, Succinea spp., Vitrina pellucida, and Zonitoides nitidus) were found naturally infected, with a mean of 4.3±5.2 larvae/gasgtropod. Succinea spp. was the most abundant gastropod, and together with Deroceras agreste, D. reticulatum, and Arion subfuscus was the most probable source of E. alces infection. Further study is required to follow and evaluate the effects of the culling on E. alces as well as on the moose population at Utö.