Mp. Russell et al., FIELD ESTIMATES OF GROWTH AND MORTALITY OF THE GREEN SEA-URCHIN, STRONGYLOCENTROTUS-DROEBACHIENSIS, Ophelia, 48(2), 1998, pp. 137-153
Growth and annual mortality rates of the green sea urchin, Strongyloce
ntrotus droebachiensis, were estimated by marking individuals with flu
orescent tags, releasing them in the field, and collecting them 1 year
later. In 1994, 533 animals were tagged in 7 tidepools and in 1995, 4
58 were collected of which 262 were tagged. Tanaka function growth par
ameters were estimated for the demi-pyramids, or ''jaws,'' one of the
ossicles of Aristotle's lantern. Estimates of annual test diameter gro
wth were attained by calculating the allometric relationship between j
aw and test diameter. By assuming size at settlement (0.5 mm test diam
eter) is age zero, and using the size specific growth rates, the relat
ionship between test diameter and age was established. Our results ind
icate that these animals are long lived and slow growing. The largest
sea urchins in our samples may be more than 50 years. The difference i
n size between tagged and untagged sea urchins in the 1995 collections
strongly suggests that smaller individuals may tend to migrate more t
han larger ones.