TIMING OF METAMORPHOSIS AND ESTUARINE ARRIVAL ACROSS THE DISPERSAL RANGE OF THE JAPANESE EEL ANGUILLA-JAPONICA

Elvers of the Japanese eel Anguilla japonica Temminck & Schlegel were collected from 6 estuaries in Taiwan, China and Japan. The fish were a ged by counting otolith daily growth increments. The time of metamorph osis from leptocephali to glass eels was determined from the otolith i ncrements where the width and strontium:calcium ratios changed drastic ally. Age upon arrival at the estuaries (mean +/- SD) was 154.71 +/- 1 0.69 to 182.06 +/- 12.43 d, while age at metamorphosis was 115.8 +/- 8 .13 to 137.85 +/- 11.28 d. Both ages showed a geographic dine that inc reased from south to north. The time from metamorphosis to arrival at the estuaries averaged 31.73 +/- 7.58 to 45.02 +/- 9.21 d. The lengthy duration of the leptocephalus stage and differences in the timing of metamorphosis are the principal factors in the long-distance dispersal of the eel.