Bellinger Ecohealth Monitoring Project: Freshwater Fish. A report to the Northern Rivers Catchment Management Authority
Gilligan, D., 2011. Bellinger Ecohealth Monitoring Project: Freshwater Fish. A report to the Northern Rivers Catchment Management Authority, November 2010. 27pp.
The condition of the freshwater fish community of the Bellinger and Kalang River catchments within the Bellingen Shire Council area was undertaken between November 2009 and March 2010 as part of the Northern Rivers Catchment Management Authority’s Bellingen Ecohealth Monitoring Project. Little freshwater fish sampling within the Bellinger and Kalang River catchments has been undertaken in the past and this survey represents the first comprehensive assessment of the entire fish community in the study area. Details of the numbers of fish, biomass and community composition were recorded and two key aspects of condition: species loss or ‘expectedness’ and the ‘nativeness’ of the fish community are reported.
Eighteen sites within the study area were sampled and 18 of the 24 (75%) native freshwater fishes predicted to have existed within the study area prior to European colonisation (prior to ~1770) were collected. Only a single alien species (eastern mosquitofish) was detected.
Freshwater fish communities within the Bellingen Shire Council portions of the Bellinger and Kalang River catchments were in Moderate condition at the time of sampling. Overall fish community condition ranged from Good in the coastal plain zone, to Moderate in the lowland zone and Poor in the slopes, upland and highland zones.
Given that only a single species of small bodied alien species was collected from only a single location and that 17 of the 18 sites attained perfect ‘nativeness’ condition ratings, alien species had little to no negative influence of fish community condition across the study area.
In contrast, overall expectedness was Poor across the study area, suggesting that a large proportion of the species that are expected to have occupied sites with the study area prior to European colonisation have been lost or have restricted distributions within the catchment. Six species (25%) expected to have been present in the Bellinger and Kalang River catchments were not collected at any site surveyed. However, all but one of these were considered to be naturally rare in the study area anyway. Perhaps more important was that the 18 native freshwater fishes that were collected, were generally found at fewer sites than expected. Expectedness was greatest in the coastal plain zone which was rated as Moderate. The expectedness indicator then deteriorated to Poor condition in the lowland zone and Very poor in the upland & highland zone. Whilst there is some justification for considering that the expectedness indicator may tend to underestimate the condition of the fish community of the upper catchment zones, the overall assessment of Poor expectedness is a reasonable approximation of the catchment-wide condition given the lower than expected native species richness at the majority of sites.
With a combined Poor catchment-wide rating for species loss and Good nativeness rating, an overall catchment-wide fish community condition rating of Moderate is justified.