Reproductive cycle, fecundity, and seasonal distribution of the anglerfish Lophius litulon in the East China and Yellow seas

The reproductive cycle, sexual maturity, fecundity, and seasonal distribution of the anglerfish Lophius litulon were studied from a total of 989 specimens collected in the East China and Yellow seas between March 1991 and July 1997. Males and females reached 50% sexual maturity at 362 mm TL (age 5.4) and at 567 mm TL (age 6.2), respectively. The histology of the gonads showing seasonal changes in both the gonadosomatic index (GSI) and hepatosomatic index (HSI) are described. Mean GSI of females increases rapidly with ovarian development, whereas mean HSI decreases from the middle of vitellogenesis until the ovaries have fully matured. Segregation of oocytes by size within the ovary suggests that L. litulon spawns in batches, which was confirmed by observation of a captive specimen. Batch fecundity (BF) in 15 females with secondary yolk stage ovaries was related to total length (TL, mm) by the equation BF = (-1.64 × 10⁶) + 3688.13 TL (546≤TL≤846). In September, most specimens of both sexes were collected in the Yellow Sea. Between November and January their distribution extended from the Yellow Sea into the East China Sea. During the spawning season (February to May), sexually immature individuals were collected throughout the East China and Yellow seas, whereas sexually mature individuals were caught only in the East China Sea and the coastal waters off Kyushu Island, Japan. The spawning grounds of L. litulon extend widely from waters of the East China Sea to inshore waters of Kyushu.