Age and Growth of the Elongate Ilisha Ilisha elongata

摘要

We present age and growth data for Ilisha elongata, based on 363 specimens caught in 1999 and2000 around Jeju Island and the southwest coast of Korea. Scale and ring radii of each ring groupshowed a direct one-to-one relationship, with ring radius increasing as scale radius increased.The relationship between fork length and scale radius was FL=39.553SR+60.935 for females,FL=39.474SR+54.026 for males, and FL=39.608SR+57.547 for both sexes. Monthly changes inthe marginal index indicated that a new ring appears once each year (in July). Maximum age,mean age and mean fork length offish were 10 years, 5.0 years, and 349 mm, respectively. VonBertalanffy's growth equations were FL,=495.4xl-exp(-0.2586(t+0.6487)) for fork length (mm)and W_t=l,112.5xl-exp(-0.2586(t+0.6487))~(2.874) for body weight (g) for both sexes. Monthlychanges in the gonadosomatic index (GSI) indicated that the spawning period was in June andJuly, which corresponded closely with ring formation time. Differences in monthly GSI changesin 1999 and 2000 may be related to water temperature variation. Fecundity ranged from 5,664 to176,290 eggs per individual (n=43, fork length 264-470 mm). The relationship between fecundity(F) and fork length was F=7.7xlO~(-7)xFL~(4.9269).