Larval distribution of blue grenadier (Macruronus novaezelandiae Hector) in south-eastern Australia: further evidence for a second spawning area

Abstract

Small numbers of blue grenadier, Macruronus novaezelandiae, larvae were found in coastal waters off eastern Victoria and southern New South Wales in August 1993. This is the first record of larval blue grenadier from mainland Australian waters. It is considerably further north than previous records of larvae and remote from the single known spawning ground off western Tasmania. Larvae were aged between 17 and 36 days and were largely confined to an inshore northward flowing water mass. Back calculated spawning dates indicated that larvae from eastern Victoria/southern NSW were spawned earlier than larvae collected during the same period off western and southern Tasmania. Otolith increment widths were significantly wider in larvae caught in eastern Victoria/southern NSW suggesting that they experienced faster growth and development conditions than the Tasmanian larvae. Three-dimensional modelling of circulation and particle advection suggested that the source of eastern Victoria/southern NSW larvae was most likely eastern Bass Strait. These data suggest that there is a second, albeit limited, spawning area for blue grenadier in south-eastern Australia.