Distribution and growth of juvenile mulloway, Argyrosomus hololepidotus (Pisces: Sciaenidae), in the Hawkesbury River, south-eastern Australia

Abstract

The distribution, recruitment, relative abundance and growth of juvenile mulloway, Argyrosomus hololepidotus Lacepede, was investigated in the Hawkesbury River. Otter trawling was used monthly between July 1986 and March 1988 at 12 sites along a salinity gradient over 85 km of the estuary. The greatest numbers of juveniles were caught at sites in the mid section of the estuary (20-40 km from the mouth) where salinities were greatly reduced. No A. hololepidotus were caught at sites that were permanently fresh water and few were caught at the marine-dominated sites closest to the mouth of the estuary. The greatest numbers of juveniles were caught between March and September (autumn-winter) and the fewest between October and January (spring-summer). Juveniles with an estimated age of 2-6 months were caught between February and July (late summer-winter) each year at a size of 30-150 mm total length. Juveniles increased in length by 80-100 mm between March and October.