Census of seabird colonies on Nordaustlandet, Svalbard, and in neighbouring localities in 1978 and 1979

Seabird colonies were censused during the summer expedition of Norsk Polarinstitutt to Nordaustlandet, Svalbard, in 1978 and 1979, and to Kongsøya in 1979. An outline is given of the distribution of the species together with an estimate of the number of breeding pairs in the colonies. Twentv-five colonies were censused; seven were visited both years. Four colonies with more than 1,000 breeding pairs of the most abundant species, Briinnich's guillemot and kittiwake, were found on Nordaustlandet.     

Food energy requirements of the harp seal (Phoca groenlandica) population in the Barents and White Seas

The harp seal ( Phoca groenlandica ) population of the Barents and White Seas has probably decreased from about one million individuals to half this size the last few years. Energy requirements of the population have been estimated by use of the simulation model SEAERG. In this model the energy requirements of an individual seal from each age group is multiplied with the group size and summed to provide the requirements of the population. In addition to population size and age structure the total food and energy requirement is sensitive to individual activity levels as well as metabolic levels and other specified physiological functions. The interactions between the seal population and fisheries depends on the caloric density of the prey species which varies with season and location. Realistic simulations of interactions between seals and fisheries require more information about spatial and temporal variations in the prey selection of harp seals than is available today.
Present estimates indicate average maintenance requirements of about 13,600 and ll,150kcal/day for adult female and male harp seals respectively. The high value for the females is due to the costs of pregnancy and lactation. With a mean energy density of prey of 1500 kcal/kg, the corresponding food consumption is 9 kg/day for females and 7.4 kg/day for males.     

Reindeer population size and trend on Edgeøya Svalbard

Two censuses made of the population of Svalbard reindeer on Edgeøya in 1983 and 1996 resulted in 1586 and 2434 individuals respectively. Together with data from earlier population surveys (1969-77), this indicates, numerically, a population growth during the period 1969-96. Because of the weaknesses in the different census methods used, we cannot conclude that in reality a population growth has taken place even though the numerical data is correct. Therefore an average population size of 1730 (± 451 SD) individuals for the period 1969-96 is suggested. Earlier estimates of vegetated area indicate that the present data corresponds to reindeer densities averaging 1.05 and ranging from 0.79 to 1.47 individuals/km².     

Estimates of energy expenditure and energy consumption of ringed seals (Phoca hispida) throughout the year

We have employed a model for the energy balance of seals to estimate the energy consumption and energy expenditure of ringed seals throughout the year, using biological and physical parameters as input. Data on growth and seasonal changes in body mass and fat content "drives" the seasonal dynamics of the model output. The energy requirements for lactation and activity are based on data from earlier published studies. The analysis suggests that the food intake of ringed seals is highly seasonal. In adult males it is low during the periods of territory defense, mating and moulting from March to June. During this period the seals lose body mass, mainly as fat. The model predicts that lactating females increase their food intake to some extent during the approximately six-week lactation period. After the ice breakup, food intake increases in both sexes, partly as a result of increasing maintenance energy requirements, and partly because the body fat stores are rebuilt in late summer and autumn. The over-all energy requirements of the ringed seal appear to be basically similar to those of terrestrial mammals.     

Polar bear hunt strategies evaluated by a Leslie matrix population model

An APL Program for a Leslie matrix population projection is developed and applied to analysis of a Canadian polar bear population. Hunting specified with respect to sex ratio within a total quota may be included in the projections. Application to the lower central arctic islands' polar bear population of 1100 animals indicates a growth to 1560 animals during ten years without hunting. Projection with two males taken for each female indicates that 54 animals may be taken from the population each year. However, the same sized hunt, but with a one-to-one sex ratio, caused a significant depression of the population.     

Comments to a polar bear population model

Larsen, T. & Ugland, K. I. (Polar Research 2 n.s., 117–118) note correctly that a Leslie matrix model treats cubs and females as independent units which is not the case lor polar bears. Population projections using the Leslie model with hunting mortalities added are instructive first approximations in evaluations of field data, however, and are recommended as exercises also for polar bear biologists. An APL programme for such projections is available.