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

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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). WGN_DOCS-#1100598-V3 PAGE 93 OF 160
River and stream water quality and ecology in the Wellington region: State and trends Figure 7.1: NZFFD records for rivers and streams in the Wellington region, based on data extracted from the NZFFD in April 2011 Table 7.4: Summary of fish species recorded in the Wellington region based on 583 river and stream records extracted from the NZFFD for the period 1990 to 2010. The threat categories from Allibone et al. (2010) are also listed. * and ** indicate diadromous species and ‘marine wanderers’, respectively Common name Scientific name No. of records Frequency of occurrence (% of sites) Threat category Longfin eel* Anguilla dieffenbachia 359 61.6 At risk (declining) Redfin bully* Gobiomorphus huttoni 201 34.5 At risk (declining) Shortfin eel* Anguilla australis 190 32.6 Not threatened Brown trout Salmo trutta 160 27.4 Introduced & naturalised Common bully* Gobiomorphus cotidianus 123 21.1 Not threatened Koaro* Galaxias brevipinnis 123 21.1 At risk (declining) Banded kokopu* Galaxias fasciatus 78 13.4 Not threatened Inanga* Galaxias maculatus 73 12.5 At risk (declining) Upland bully Gobiomorphus breviceps 63 10.8 Not threatened Torrentfish* Cheimarrichthys fosteri 48 8.2 At risk (declining) Giant kokopu* Galaxias argenteus 41 7.0 At risk (declining) Cran’s bully Gobiomorphus basalis 39 6.7 Not threatened Brown mudfish Neochanna apoda 34 5.8 At risk (declining) Common smelt* Retropinna retropinna 27 4.6 Not threatened Dwarf galaxias Galaxias divergens 27 4.6 At risk (declining) Shortjaw kokopu* Galaxias postvectis 23 3.9 At risk (declining) Bluegill bully* Gobiomorphus hubbsi 21 3.6 At risk (declining) Lamprey* Geotria australis 18 3.1 At risk (declining) Perch Perca fluviatilis 9 1.5 Introduced & naturalised PAGE 94 OF 160 WGN_DOCS-#1100598-V3
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