Mortality and longevity in the whelk Dicathais orbita (Gmelin)

Abstract

A population of the whelk Dicathais orbita (Gmelin) at Fish-Hook Bay, Rottnest Island, in Western Australia, was found to have a high annual mortality and hence a low average life expectancy. A longevity of 19 years has been estimated but the average life expectancy is not more than 5 years. The mortality rate of the animals on the reef platforms (1-S = 0.46; M = 0.62) was found to be independent of age. A life table for D. orbita is presented and discussed, and these data compared with data on some other predatory gastropods.