Journal Article

Development in the Baltic grey seal (Halichoerus grypus) and ringed seal (Phoca hispida) populations during the 20th century

Hardin, K.C, Haerkoenen,T.J. (Swedish Museum of Natural History, Kaerna (Sweden). Dept. of Ecotoxicology)

1999

Overview

Development in the Baltic ringed (Phoca hispida) and grey seal (Halichoerus grypus) populations during the past century is reconstructed using uniquely detailed hunting records from the Nordic countries and published data on demographic parameters. A projection model was elaborated where annual variations in the composition of catches by sex and age were taken into account. Grey seals decreased from 88 000-100 000 in the beginning of the century to approximately 4000 in the late 1970s. The Baltic ringed seal population decreased during the same period from 190 000-220 000 to approximately 5000. In the mid-1960s, the remaining populations were afflicted by sterility, probably caused by organochlorines, which inhibited natural growth during a 25-years period. Thus, the decrease in seal numbers was a consequence of excessive hunting, but the present low numbers are due to lowered fertility rates after 1965.

• Publisher: Royal Swedish Academy of Sciences
• Subject: Age structure / ANIMAL POPULATION / BALTIC SEA / CAZA / CHASSE / ENDANGERED SPECIES / ESPECE EN DANGER / ESPECIES EN PELIGRO DE EXTINCION / ESTRUCTURA DE LA POBLACION / FERTILIDAD / FERTILITE / FERTILITY / FOCA / Halichoerus grypus / HUNTING / Ice / MAR BALTICO / MER BALTIQUE / Mortality / Phoca hispida / PHOQUE / POBLACION ANIMAL / POLLUTION DE L'EAU / POLUCION DEL AGUA / POPULATION ANIMALE / Population estimates / Population growth rate / Population size / POPULATION STRUCTURE / Scandinavia / Seal hunting / SEALS / Sex ratio / STRUCTURE DE LA POPULATION / WATER POLLUTION