Recruitment Ecology of Maccullochella in the Upper Murrumbidgee 2011-2013 (#109)
Maccullochella larval ecology in upland rivers has been little studied. This is in contrast to the situation in lowland rivers systems where the recruitment and spawning ecology of cod have been extensively investigated. Six sites spread over 40 kilometres of the Murrumbidgee River in the ACT were sampled for drifting larval fish in the spring/early summer of 2011, 2012 and 2013. Maccullochella larvae were the most common species captured. Spatial and temporal variation in larval drift was seen. 2012 saw low levels of larval drift compared to 2011 and 2013. But overall the high larval density observed (mean of 20 larvae per ML during peak week of drifting period) suggests this reach may play an important role for natural recruitment of cod into the Murrumbidgee River system. Size and age profile of potential recruits was examined. Relationships between observed larval cod drift, and seasonal and river conditions was considered but no significant associations were seen. The distance Maccullochella larvae drift from the nest before settling remains a knowledge gap and specific patterns of larval cod drift in upland river systems may have implications for management of the two sympatric Maccullochella species (M. peelii and M. macquariensis) in this river.