Size and Age at Maturity of the Sea Urchin Strongylocentrotus intermedius along the Northwestern Coast of the Sea of Japan

The effects of oceanic and biotopic factors on the size and age at maturity of sea urchins Strongylocentrotus intermedius alongside the northwestern coast of Primorsky krai are discussed. The growth rate and body size of the sea urchin at 50% maturity of the population corresponds to 30–35 mm in clusters with high growth rates and to 20–22 mm in clusters with low growth rates. In populations inhabiting southern areas of northern Primorsky krai, S. intermedius reaches final maturity at 40–45 mm, while in areas further to the north, at 26–30 and 31–35 mm. The age at final maturity in areas between Ezhovaya Bight and Cape Khitrovo and along Cape Nadezhdy was 4+ to 5+, while in other areas it was 3+. We argue that the differences in sizes and time periods in which maturity is reached in various S. intermedius populations depend on the local environment within the studied coastal area, primarily, on the abundance of available food, rather than on latitudinal zoning.