3. Sources of ecological information
3.1 Data used in GIS
The Department of Conservation provided GIS data for threatened and weed plants, lizards (geckos and skinks), and threatened birds. In addition, Department of Conservation provided a "Sites of Natural Significance" GIS layer, which is a compilation of data from the following Department of Conservation databases: Recommended Areas for Protection; Special Sites of Significance to Wildlife; and Wetlands of Ecological and Representative Importance.
Freshwater invertebrate data was obtained from Environment Canterbury, and records of adult caddisflies (Trichoptera), which have aquatic larvae, were obtained from John Ward at the Canterbury Museum.
Data on the habitats and threats of salmonid fish (trout, salmon and charr), and wetland birds and plants were obtained from Environment Canterbury's GIS database.
Freshwater fish records were obtained from the NZFFD, which is administered by NIWA. Additional fields were added to the NZFFD records, including classifications according to threatened species status, whether or not the species is diadromous (with freshwater and marine life history stages), and whether or not the species were salmonids. Threatened species rankings followed the Department of Conservation classification of Molloy et al. (2002), as outlined in Table 2.1. Where additional potential sources of fish data were identified (see below) records were compared with the NZFFD, which was always found to contain the additional data source entries.
The River Environment Classification (REC) is a system that classifies New Zealand's rivers at six hierarchical levels (Snelder et al. 2004). The REC was produced for Ministry for the Environment by NIWA. The classification hierarchy includes information on climate, source-of-flow, geology, landcover, stream order (or size), and valley slope for stream reaches. For this project REC reach attributes were joined to the nearest NZFFD record, imparting habitat information to the NZFFD records and enabling predictions on the likelihood of fish occurrence to be made based on the REC. A more complete discussion of this process is provided in Section 4.3.
3.2 Additional data sources
Central South Island Fish and Game provided a range of useful data following a meeting with Kingett Mitchell staff in early October. The data provided by Central South Island Fish and Game included:
- chinook salmon spawning count and redd count data for the Hakataramea River
- description of the sockeye salmon population
- trout spawning data for the Maryburn, Forks Stream, Irishman Stream, Black Forest Stream, Ahuriri River, Ohau River and the Awakino River
- description of trout population data for Lake Alexandrina, Ohau and Middleton
- trout population data for Mistake River.
The Environment Canterbury salmonid habitat GIS layer included descriptions of salmonid habitat and values at all of the sites listed above, and was constructed in consultation with Central South Island Fish and Game Council. However, while the Central South Island Fish and Game Council data is included in the Environment Canterbury salmonid layer, it also contains information on population trends over time that is not easily represented in GIS. This information is held by Ministry for the Environment and may be of use to the Board when assessing long term trends in salmonid populations.
Information on the habitats and locations of native freshwater fish in the upper catchment (above the Waitaki dam) is included in Mitchell and Davis-Te Maire (1993), and in draft Department of Conservation reports by Bowie (2004) and Elkington and Charteris (2004), plus several other sources identified in the bibliography. In all cases, fish records and associated habitat data was found to have been included in the NZFFD records obtained for this project. However, the reports do provide some additional insight into the ecology of native and introduced fish species in the Catchment that is not easily represented in GIS.
Additional data contained within the Project Aqua invertebrate report (Stark and Suren, 2003) would have improved the coverage of invertebrate ecological values data for the Waitaki River mainstem and tributaries in the lower catchment. This data was not able to be obtained from Meridian Energy Ltd during the preparation of this report, but may become available to the Board in the near future.
The New Zealand mayfly database is administered by Canterbury Museum. Mayflies (Ephemeroptera) have aquatic larvae and flying adult stages, and are important food to many native and introduced freshwater fish species. The mayfly data was not obtained because the Environment Canterbury invertebrate and caddisfly GIS layers are considered sufficient, without the need for this additional data source.
The National Vegetation Survey database is administered by Landcare Research. Vegetation Survey data for the Waitaki Catchment was obtained, but it was not entered into the GIS due to uncertainty regarding its usefulness. Most of the information on significant vegetation and threatened plant species is captured in the GIS data obtained from Department of Conservation and Environment Canterbury, and the National Vegetation Survey data is unlikely to add significant value to the existing GIS layers.
At the time of writing, ecological data from Department of Conservation's Tenure Review process was patchy and much of it had not been entered into databases. However, most of the fish records have been entered into the NZFFD (Sjaan Charteris, Department of Conservation, pers comm.). Given the generally good coverage of ecological GIS data obtained for the Catchment, and the recent freshwater fish sampling efforts by Department of Conservation, the unclassified Tenure Review data is unlikely to add significant value to this project.
Resource consent applications often contain assessments of freshwater bodies, and there have been many relatively recent applications in the Waitaki River Catchment. However, ecological data obtained from consent applications was not in electronic format, and had varying degrees of data quality. Given the questionable value of the ecological assessment information, and the difficulty in extracting information from individual consent files, resource consent information was limited to that already entered into the NZFFD.
Data from reports on the significance of wetlands (Davis, 1999) and aquatic habitats (Taylor et al., 1998) were not included as GIS layers, as the more recent plant, bird, and salmonid Environment Canterbury GIS layers were considered more up to date.
Bibliographies including information regarding Project River Recovery (from Department of Conservation) and the Waitaki River in general (from Ministry for the Environment) were inspected for additional information sources of value to this project. While these reviews included a wealth of reports, most of it was already captured in the ecology GIS layers discussed above and was therefore not included in this assessment.
Information on terrestrial insects (eg, Sinclair, 1995) was excluded from the GIS layers, due to the aquatic focus of this report.
The GIS data did not include the fauna of groundwaters or hyporheic zones (shallow groundwater where groundwaters and surface waters interact). Although research on the ecology of subsurface environments has grown in recent years, and sampling in most stony-bedded rivers and streams have revealed an abundant subsurface fauna (Burrell and Scarsbrook, 2004), there has been only limited sampling of subsurface communities in most river systems, including the Waitaki River Catchment. However, sampling in the Otematata River has revealed an abundant hyporheic fauna (termed the "hyporheos"), while crustaceans and other groundwater fauna have been collected from groundwater wells around Otematata and in the lower reaches of the Catchment, near Glenavy (Graham Fenwick, NIWA, pers comm.). Groundwater and hyporheic fauna records will be entered into NIWA's Freshwater Biota Information System database in the future, but were not available at the time of writing.
