Abstract
We studied age and growth of the sea urchin, Pseudocentrotus depressus, to obtain some informations regarding its sustainable production and appropriate resources reinforcement. The samples were collected at two locations (Ongpo and Bubhwan) in Jeju, Korea. Annual rings were formed from October to January, and this period was well matched with the time just prior to or during their reproduction. Two population regression lines generated by using Walford's plotting with mean radius of each age group showed significant differences in their growth rate between the two sampling locations (p<0.0l). When the regression equations were calculated using either madreporite's radius (R) and test diameter (L) or body weight (W) and test diameter (L), the results were L=23.830+ 11.735R and $W=0.0004L^3$, and no statistically significant differences were detected between the two populations (p>0.2). Based on the data of madreporite's radius and test diameters, two estimated growth equations were $L_t(mm)=72.988(1-e^{-0.412(t-0.596)}\;and\;L_t(mm)=70.195(1-e{-0.365(t-0.51l)}$ in Ongpo and Bubhwan population, respectively. Three distinct annulus groups were recognizable within the distribution of the radii of the annual rings measured from age I to age 5. The mean radii calculated from the same annulus group were all identical even though they were from different age groups.
