FISHERIES RESEARCH INSTITUTE,MOA,TAIWAN

The reproductive biology of the escolar (Lepidocybium flavobrunneum) was examined through monthly samples collected from the Shinkang fish market of Taitung county from March 2009 to March 2011. A total of 299 length-weight measurements were collected (fork lengths ranged from 40-155 cm and round weights ranged from 0.8-4.5 kg), and gonads were sampled. The gonadosomatic index (GSI) ranged from 0.028-12.95, with monthly changes in the GSI indicating that the mature stage peaked from February to March. Observations of the histology of the monthly variation in gonads also indicated that the greatest proportion of mature females occurred from February to March. Based on the variation in the diameters of the oocytes, the spawning pattern of the escolar is considered asynchronous. The estimated 50% length-at-maturity (L50) was 106.5 cm and the 95% length-at-maturity (L95) was 129.5 cm. In the total sample, 87% of the oocytes were immature, 7% were mature, and 6% were spent or at the rest stage. As concluded from the absence of hydrated oocytes in the samples, no spawning or recently spawned specimens were observed. The estimated total fecundity was 46±31 (S.D.) million eggs, and the relative fecundity was 2,604 ± 700 (S.D.) eggs/g.