Reproductive biology of the Australian herring Arripis georgiana

Arripis georgiana was collected from along the Western Australian and South Australian coasts at regular intervals between October 1996 and December 1998. The trends exhibited during the year by gonadosomatic indices, gonadal maturity stages and oocyte stages demonstrate that spawning is restricted to south-western Australian waters from at least as far north as similar to 28 degrees 43'S to as far east as similar to 119 degrees 24'E, and that it occurs mainly during late May and early June. The simultaneous presence of post-ovulatory follicles and hydrated and yolk-granule oocytes in some ovaries during the spawning period indicates that A. georgiana is a multiple spawner, i.e. females spawn more than once in a breeding season. In south-western Australia, where all life-cycle stages are found, the overall sex ratio in catches collected by netting was close to parity, whereas females predominated in those obtained by anglers. The length at which 50% of fish reached maturity was 197 mm for females and 179 mm for males, and just over 50% of females and similar to 80% of males attained maturity at the end of their second year of life. The implications of these data for management of the fishery for A. georgiana are discussed.