Despite its ecological and economic importance, there are relatively few field studies that document basic demographic parameters of green sea urchins such as size-specific growth and mortality rates. These markers stain the skeletal elements and indicate size at the time of marking. We returned one year later in 1995 and collected all the sea urchins in these pools, measured them, and assessed growth using the fluorescent marks on the demi-pyramids of tagged animals. These data yield size-specific growth rates and estimates of mortality. Compared to the two congeners in the eastern Pacific, the purple sea urchin, S. purpuratus , and the red sea urchin, S. franciscanus , green sea urchins in Maine are slow growing animals.
Mortality rates appear to be within the ranges observed for the Pacific congeners.