River and stream water quality and ecology - Greater Wellington ...

River and stream water quality and ecology in the Wellington region: State and trends
Table 7.3: IBI, Water Quality Index (WQI), periphyton and macroinvertebrate (MCI)
classes (grades) for five RSoE sites, based on analyses presented in Tables 4.5,
5.3 and 6.2 of this report. Habitat quality classes from one-off assessments in
2008 (see Appendix 8) are also presented
Class Whareroa S at
QE Park
RS12 RS18 RS44 RS49 RS52
Kaiwharawhara S at
Ngaio Gorge
Totara S at
Stronvar
Beef Ck at
headwaters
Tauanui R at
Whakatomotomo Rd
IBI Very Good Fair Good Poor Poor
WQI Poor Fair Excellent Excellent Excellent
Periphyton N/A 1 Poor Fair Excellent Excellent
MCI Fair Fair Fair Excellent Excellent
Habitat Poor Poor Fair Excellent Excellent
1 Periphyton is not assessed at this site because it has a soft substrate.
as ‘poor’ perhaps suggests that the limited assessments undertaken to date have
not captured some of the habitat characteristics critical for fish communities.
Further, the divergence of fish community condition from other indicators of
stream health at some sites is a clear indication that fish monitoring is required
to provide a more complete picture of aquatic ecosystem health.
(b) NZFFD data
All NZFFD records for fishing undertaken in river and streams in the
Wellington region between 1990 and 2010 are plotted in Figure 7.1. It is clear
that not all catchments have been surveyed equally, and in some cases, even
relatively large catchments contain few or no records. For example, there are
no NZFFD records for the Whangaehu River catchment, a relatively large
tributary of the Ruamahanga River. When compared with the rest of the region,
a significant proportion of the eastern Wairarapa is poorly represented in the
NZFFD. This spatial limitation needs to be kept in mind when interpreting the
results in this section.
Between 1990 and 2010, a total of 26 freshwater fish species were recorded in
the NZFFD for river and stream environments across the Wellington region
(Table 7.4). Of these 26 species, 20 are indigenous and six (brown and rainbow
trout, perch, goldfish, tench and rudd) are introduced species that have
naturalised in the region (ie, have formed self-supporting populations). Of the 20
indigenous species, 15 are diadromous and one, the yelloweye mullet, is
considered a marine wanderer (McDowall 2000). Over half of the indigenous
species listed in Table 7.4 are categorised as ‘at risk’ and populations of these
species are considered to be declining across New Zealand (Allibone et al. 2010).
The fish species recorded most commonly in the NZFFD between 1990 and
2010 were longfin eel (62% of sites), redfin bully (35%), shortfin eel (33%)
and brown trout (28%). Six species were found in than less than 1% of all
records; two indigenous species (giant bully and black flounder) and four
introduced species (goldfish, rudd, tench and rainbow trout) (Table 7.4).
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