Reproductive investment in female fur seals in relation with age of puberty

Abstract

Purpose: To find out the main parameters of the life cycle and the reproductive contribution of females depending on the age of their puberty.Method: Analysis of metal tagging in fur seal pups and tag return obtained by reading tags on live fur seals using optical instruments. Reading marks was carried out in 1982-2014 during the harem period on the Central site of the Northern rookery (Bering Island).Novelty: For the first time, data have been obtained on the reproductive contribution of female fur seals during the life cycle in relation to their age of puberty.Results: The birth of puppies in early maturing (at 2-3 years old) females is shifted to an earlier age, their life cycle is shorter, natural loss after the first fertilization is higher, they miss more breeding seasons during the life cycle. During the life cycle, early maturing females give birth to about 40% of the total number of puppies born by tagged females, and most of them (31%) are under the age of 8 years. Medium maturing (at 4-5 years old) females give birth to almost the same number of puppies (39.7%), however, the proportion of puppies born in these females is distributed more evenly over the life cycle. In late-maturing (at 6-7 years old) females and females entering the rookery at the age of 8+ years, the reproductive contribution is lower - they give birth to 13.4% and 6.3% of puppies, respectively, and the age at which puppies are born is higher - mostly 11 years and older.