Freshwater fish communities of the Hunter, Manning, Karuah and Macquarie-Tuggerah catchments: a 2004 status report.
Howell T and Creese R (2010) Freshwater fish communities of the Hunter, Manning, Karuah and Macquarie-Tuggerah catchments: a 2004 status report. Final report to the Hunter-Central Rivers Catchment Management Authority for Project No. CRH0012. Industry & Investment NSW – Fisheries Final Report Series No. 126. Cronulla, NSW, Australia. 93pp.
Fish communities were sampled in 4 catchments within the jurisdictional area of the Hunter Central Rivers Catchment Management Authority (HCRCMA). Twenty-seven monitoring sites were randomly selected to benchmark the fish community in 2004 across the Hunter, Manning, Karuah and Macquarie-Tuggerah catchments. Sampling was done within 5 separate altitude zones to give an adequate description of the fish community from the immediate coastal zone to the highlands at Barrington Tops. Fish were sampled using a combination of electrofishing and small, unbaited traps.
Twenty-three fish species were recorded – 18 native species and 5 alien ones. The 2 alien trout species were only captured at Stewarts Brook in the highland zone – the highest site in the Hunter catchment. No native fish occurred at this site, making it unique amongst the sites sampled. The other 4 altitude zones – coastal (< 50 m), lowland (50–200 m), slopes (200-400 m), upland slopes (400–700 m) – were dominated by native fish species. The fish community in the coastal zone was characterised by a greater abundance of sea mullet and striped gudgeon than the other four zones. A notable difference between the lowland and the upland zones was predominantly driven by the higher abundance of Australian smelt and long-finned eels in the lowland zone and the absence of sea mullet in the upland zone. The highland zone had no Australian smelt, a reduced abundance of long-finned eels, and was dominated by the alien gambusia.
The proportional abundance of native fish species in the Hunter catchment across all altitude zones was relatively high. In the slopes and upland zones, the influence of large common carp increased the proportion of the fish biomass that was non-native. All fish sampled in the slopes and upland zones of the Manning catchment were native. With the exception of the highland site, the proportion of native fish species across all other altitude zones was very high. Native species dominated the abundance in all zones except the highlands, where large numbers of gambusia dominated numbers. Gambusia was the only alien fish species recorded in the Karuah and Macquarie-Tuggerah catchments.
The most abundant species in the Hunter catchment in 2004 were Australian smelt, long-finned eels, sea mullet and gambusia. Biomass was dominated by sea mullet, common carp and long-finned eels, the latter being the most widespread species. Goldfish, striped gudgeon, bullrout and rainbow trout contributed <1% of the total catch. Australian smelt and long-finned eels were the most numerous species in the Manning catchment, with long-finned eels and sea mullet dominating the total biomass. The three rarest taxa were bullrout, freshwater mullet and dwarf flat head gudgeon. The most abundant species in the Karuah catchment were sea mullet, long-finned eels and Australian smelt. Sea mullet dominated the biomass, with significant contributions from long-finned eels, Australian bass and freshwater mullet. Fish abundance in the Macquarie-Tuggerah catchment was dominated by striped gudgeon, empire gudgeon and long finned eels, with long-finned eels dominating the biomass. Only one specimen of common jollytail was caught throughout the survey, and it came from the Macquarie-Tuggerah catchment. The second rarest fish were short-finned eels.
The fish survey done in 2004 provided a comprehensive benchmark against which future changes can be assessed. More recently, the NSW government’s Monitoring Evaluation & Reporting (MER) program has commenced. ‘Fish assemblage structure’ is one of the indicators of ecosystem condition used for the Riverine theme of MER. Sampling for this MER indicator in the Hunter Central Rivers CMA area was done in 2007/08, effectively repeating the 2004 survey, but with an even greater number of sampling sites.