Growth and mortality estimates for red sea urchin Strongylocentrotus franciscanus from San Nicolas Island, California

Abstract

The large Strongylocentrotus franciscanus had a growth curve similar to many tropical and temperate species in that c42% of asymptotic size was attained during the first year of growth. Sea urchins at Cosign Cove grew more slowly and attained a smaller maximum size than did those at Northwest Point, so at 10 yr diameters would be 6.7 and 7.9 cm, respectively. Annual mortality rate was c10% for both sites. Although growth rates were different at the two sites, relative sizes of the demi-pyramids of Aristotle's lantern were the same. Size of demi-pyramids relative to test diameter is responsive to food abundance so the different growth rates either represent responses to environmental factors other than food or relative growth of jaws in S. franciscanus is more canalized than in other sea urchin species. -from Authors