Age and growth of damselfish (Chromis notata) in the Jeju Island

Abstract

This study was to estimate age, growth and mortality of damselfish from Jeju Island. Samples were collected monthly by liftnet during the period from September 2013 to August 2014. Of the 725 specimens, the sex ratio was significantly different from a 1:1 ratio (P<0.05). The total length ranged from 6.4 to 15.3 cm. The length-weight relationship of damselfish was W=0.0042TL^(3.588)(n=725,r2=0.8858,P<0.001). The slopes of relationship between length and weight were not significantly different between sexes (ANCOVA,F=5.89,P>0.05). MI value declined in summer and winter, which suggest that two rings are formed each year. The age of the sampled individuals, which ranged from 1 to 5 years, was estimated using the count of growth ring recorded on the otolith. Length-at-age data were fitted using von Bertalanffy growth model. The estimated von Bertalanffy growth functions were L_t=19.93(1−exp−0.21(t+0.811)) for female; L_t=16.47(1−exp−0.32(t+0.499)) for male. The estimated length-at-age was 1 year =7.8 cm,2 year=9.79 cm,3 year=11 cm,4 year=12.32 cm,5 year=15.15 cm for female; 1 year =7cm,2 year=9.76 cm,3 year=11.03 cm,4 year=12.67 cm,5 year=14.17 cm for male. Total and natural mortality were found to be Z=1.92 year−1 and M=1.22 year−1. Survival rate was 0.15 year-1.