NZ Forest and Bird Protection Society
Assessment of Outstanding Freshwater Fish Values on the Ngaruroro River
Kate McArthur
May 2013
1. Introduction
Forest and Bird contracted The Catalyst Group to outline the freshwater fauna values of the Ngaruroro River for integration into a Water Conservation Order (WCO) application to the Minister for the Environment. The brief of work included a desktop search of the literature to establish the freshwater fauna present along the Ngaruroro River and its tributaries (source to sea), a description of any outstanding freshwater values and the provision of freshwater fauna references suitable for use in the preparation of evidence as the WCO application progresses. A description of water quality and river flows is included for context, in addition to a brief description of threats to freshwater fauna and habitats.
For the purposes of the assessment the Ngaruroro catchment has been divided into two main areas; the upper river, which comprises all of the catchment upstream of Whanawhana and the lower river, which is made up of three main reaches of the mainstem and the tributaries that feed into each reach. The lower river reaches are described as: a) the braided reach between Whanawhana and Fernhill, b) the flood control reach between Fernhill and the Chesterhope Bridge and c) the Estuary (downstream of the Chesterhope Bridge).
2. Results
A total of 21 species of fish and one crustacean have been identified in the Ngaruroro catchment since the mid 1980’s in the New Zealand Freshwater Fish Database administered by NIWA and in Walls (2005). Of these species eleven are endemic to New Zealand (only breed in New Zealand) and a further nine are native (naturally occur and breed in New Zealand – but may also breed in other countries). Additionally, there are database records for unidentified eel, bully, salmonid and flounder species (Table 1). Three introduced species were found, including the pest species Gambusia affinis.
New Zealand’s freshwater fish and invertebrates have been ranked in terms of their conservation threat status (Allibone et al. 2010) using the New Zealand Threat Classification System (Townsend et al. 2008). In total nine endemic or native species that occur in the Ngaruroro catchment are classified as ‘declining’ and ‘at risk’, including koura (freshwater crayfish). Many species in the Ngaruroro, such as koaro, bluegill bully and torrentfish have had their conservation threat status increased from ‘not threatened’ to ‘at risk - declining’ to reflect the more serious effort needed to reverse the decline in native freshwater fish to avoid and prevent species extinctions in the future (Allibone et al. 2010).
Diadromy (migration between freshwater and marine environments) is a characteristic in a large proportion of New Zealand’s native and endemic freshwater fish species (Table 2). This life characteristic has significant ramifications when considering species needs for migration pathways, in particular water quality, flow and suitable habitat access between upper catchment habitats and the sea.
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Table 1. Freshwater fish and invertebrate (crayfish) species found within the Ngaruroro catchment. Endemic species only breed in New Zealand. Native species naturally occur and breed in New Zealand – but may also breed in other countries. Sources: New Zealand Freshwater Fish Database and shaded species identified in Walls (2005).
Common name* / alternative Scientific name
ENDEMIC SPECIES Black flounder Rhombosolea retiaria Bluegill bully Gobiomorphus hubbsi Common bully Gobiomorphus cotidianus Cran’s bully Gobiomorphus basalis Dwarf galaxias (northern) Galaxias aff. divergens (northern) Giant bully Gobiomorphus gobioides Koura / freshwater crayfish Paranephrops planifrons Longfin eel / tuna Anguilla dieffenbachia Redfin bully Gobiomorphus huttoni Smelt Retropinna retropinna Torrentfish Cheimarrichthys fosteri Unidentified bully Gobiomorphus sp. Unidentified eel Anguilla sp.
NATIVE SPECIES Cockabully / estuarine triplefin Grahamina nigripenne Inanga Galaxias maculatus Koaro Galaxias brevipinnis Lamprey / piharau / kanakana Geotria australis Shortfin eel / tuna Anguilla australis Unidentified flounder Rhombosolea sp. Yelloweye mullet Aldrichetta forsteri Grey mullet Mugil cephalus Kahawai Arripis trutta
INTRODUCED SPECIES Brown trout Salmo trutta Gambusia / mosquito fish Gambusia affinis Rainbow trout Oncorhynchus mykiss Unidentified salmonid Salmo sp. / Oncorynchus sp.
* Nomenclature: as outlined in McDowall RM 2001. Freshwater Fishes of New Zealand. Reed New Zealand Nature Series. Auckland, New Zealand. Identification of dwarf galaxias (northern) as per Allibone et al. (2010) for threat classification purposes.
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Table 2. Conservation threat status, migration and location of fish and koura species recorded in the
Ngaruroro River and its tributaries.
1
Common name Conservation status River
Migratory Upper reach Braided control Flood reach Estuary ENDEMIC SPECIES Black flounder Not threatened Bluegill bully At risk - declining Common bully Not threatened Cran’s bully Not threatened Dwarf galaxias (Northern) At risk - declining Giant bully Not threatened Koura / freshwater crayfish Gradual decline Longfin eel / tuna At risk - declining Redfin bully At risk - declining Smelt Not threatened Torrentfish At risk - declining Unidentified bully n/a unknown Unidentified eel n/a
NATIVE SPECIES Cockabully / estuarine marine triplefin Not threatened Inanga At risk - declining Koaro At risk - declining Lamprey / piharau / At risk - declining kanakana Shortfin eel / tuna Not threatened Unidentified flounder n/a unknown Yelloweye mullet Not threatened marine Grey mullet Not threatened marine Kahawai Not threatened marine
INTRODUCED SPECIES Brown trout n/a possibly Gambusia / mosquito fish Pest Rainbow trout n/a possibly Unidentified salmonid n/a possibly
1 As per: (fish) Allibone R, David B, Hitchmough R, Jellyman D, Ling N, Ravenscroft P, Waters J 2010. Conservation status of New Zealand freshwater fish, 2009. New Zealand Journal of Marine and Freshwater Research 44: 271 287; (koura) Hitchmough R, Bull L, Cromarty P 2007. New Zealand Threat Classification System Lists 2005. Department of Conservation, Wellington, New Zealand.
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3. Outstanding Freshwater Fauna Values
The Ngaruroro catchment comprises habitat types that support a number of freshwater species from source to sea, many of which are reliant on more than one of these habitat types for all or part of their life-cycle. Several species utilise habitats throughout the entire catchment. Nationally, the Ngaruroro River can be considered an ecologically significant habitat due to the rarity of braided rivers in the North Island, and outstanding because of the proportion that this catchment contributes to the total New Zealand braided river habitat. The extensive proportion of the upper catchment within the Conservation Estate also provides outstanding freshwater habitat in a relatively unmodified state, with very high water quality.
The iconic longfin eel is found throughout the catchment and has been recorded as common or abundant in the upper catchment and many of the upper river tributaries. Torrentfish are also found throughout the catchment and from the number of records and abundance noted in the Freshwater Fish Database the Ngaruroro can be considered to provide exceptional torrentfish habitat. Further analysis of freshwater fish records for all of New Zealand is required before the Ngaruroro can be defined as ‘nationally outstanding’ torrentfish habitat. Torrentfish are the most flow-demanding of New Zealand’s indigenous fish fauna (Jowett and Richardson 2008) with high optimum flow requirements exceeding those of trout and should be priority consideration for minimum flow and allocation setting in the Ngaruroro.
The upper catchment (above Whanawhana) supports three ‘at risk and declining’ native species known to penetrate far inland and often found at higher altitudes (torrentfish, longfin eel and koaro). All are either accomplished swimmers or climbers. Both brown and rainbow trout are found in the upper catchment.
The middle and lower reaches of the river (from Whanawhana to the Estuary) support the greatest freshwater fish diversity, as expected for the New Zealand fauna which has many species that migrate to sea to complete their life-cycle. The middle reaches of the river also support significant populations of non-migratory fish, in particular the northern dwarf galaxias (also at risk and declining). Despite the modified nature of the environment, the lower river between the Chesterhope Bridge and the sea (including the Estuary) supports a mixture of marine wanderers and freshwater species. All existing inanga spawning habitat in the tidal reaches should be considered significant due to the impacted nature of the lower river and estuary and the risks of further impact to marginal vegetation which support inanga spawning when tidally inundated. Water quality in the lower river is still very good relative to other large, modified lowland rivers.
The assemblage of freshwater fish and invertebrates across the varying habitat types in the catchment is significant in that more than half of the native and endemic species present are classified as at-risk and declining nationally and several species are found in significant populations according to survey records.
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3.1 Upper River (upstream of Whanawhana)
Longfin eel, torrentfish and koaro are the native species recorded in the upper Ngaruroro catchment. These three species are all classed as at risk and declining (Allibone et al. 2010) and although their preferred habitats are largely found in the middle and upper river reaches, their migratory nature means adequate passage throughout the lower river reaches and access to the sea is critical to their continued survival. Supporting the trout and native fisheries is a diverse and abundant aquatic invertebrate fauna with a high proportion of large EPT species (Ephemeroptera, Plecoptera and Trioptera), ideal as high quality prey items for fish (see below).
3.2 Lower River (Whanawhana to the sea)
The mid to lower reaches of the river from Whanawhana to the sea contain the largest diversity of freshwater fish species in the catchment. This is consistent with known habitat preferences for native and endemic fish species with average species diversity and abundance decreasing with distance from the sea (Jowett and Richardson 1996) and elevation (Joy and Death 2001). Low altitude habitat preferences result from the diadromous (migratory) nature of many native fish that require access between riverine and marine habitats to complete their life-cycle. However, there is some sampling bias towards the flood control and estuary reaches, with few fish records for the braided reach upstream of Fernhill (Map 1.). There is little to no survey data for any tributaries in the lower catchment.
The braided and flood control reaches of the River (between Whanawhana and Chesterhope Bridge) support good populations of dwarf galaxias, a non-migratory endemic species also considered at risk and declining. The non-migratory nature of these galaxids means any loss of habitat within their current range is a significant risk for future populations because they are not able to re-establish from inward larval migration from the sea in the way that migratory species can. Dwarf galaxids prefer slow-flowing back-water habitats which are common in the variable habitat types found in the braided reaches. The diversity of bully species in the mid to lower river is also high with five representatives from the Gobiomorphus genus present, two of which are at risk and declining (redfin and bluegill bully).
The lower river and estuary provide habitat for marine wanderers such as the yelloweyed and grey mullet, kahawai and estuarine triplefin (cockabully) as well as the enigmatic black flounder (patiki) which is known to penetrate some distance inland. Black flounder are cryptic in nature and records are rare in the North Island. The four records for the Ngaruroro should be considered significant. Inanga, found throughout the mid to lower reaches are obligate estuarine spawners. Their at risk and declining conservation status is largely linked to their reliance on estuarine spawning habitat (i.e. they are considered conservation dependent because of this habitat limitation) a habitat type which is under threat internationally. Records show some observations of inanga as common or abundant. Habitat protection of spawning areas should be considered a priority for viable species maintenance in the Ngaruroro, Tutaekuri and surrounding river systems.
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3.3 Wetlands
Lakes Runanga and Oingo are eutrophic, shallow lakes near Fernhill that are in private ownership and have been identified as having significant eel populations that are commercially fished. Commercial eel fishing is recorded as having a lesser effect on Lake Runanga as eel size classes vary more than for Lake Oingo, where there is concern that eels are being overfished (Cameron 2008). Freshwater fish records were not available at the time of writing to determine the values of these wetlands with respect to freshwater species.
The wetland habitat of Waitangi Estuary is a highly modified river mouth where the Ngaruroro and Tutaekuri Rivers meet before discharging into Hawke’s Bay. Marine and freshwater fish species utilise the estuary and it is of particular significance for the spawning habitat it provides for inanga, despite its modified nature. Walls (2005) identified the Estuary as regionally significant for its native and estuarine fish values and as a nursery for marine wanderers such as flounder, mullet and kahawai.
3.4 Tributaries
The tributaries containing records of significant freshwater fish species are generally found in the upper catchment, apart from one unnamed tributary of the braided reach. Upper catchment tributaries with at risk native species include: Kakekino, Waikarakara, Raoraoroa and Rocks Ahead Streams and Manson and Kiwi Creeks in addition to several unnamed tributaries.
However, the freshwater fish values of tributaries in the lower river, including the braided and flood control reaches cannot be accurately assessed due to a lack of survey data. Further information is needed before the significance of these habitats can be included or excluded from any conservation order or management action.
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Map 1. New Zealand Freshwater Fish Database records for the Ngaruroro River catchment (n = 160). Survey data collected between 1986 and 2011.
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3.6 Aquatic macroinvertebrates
Aquatic macroinvertebrates are used as bio-indicators of aquatic health and life-supporting capacity of rivers and streams. They are particularly useful indicators as they integrate environmental conditions over long time-frames, giving a more comprehensive picture of water quality across variable river conditions. Macroinvertebrates are also important aspects of aquatic biodiversity in their own right, providing essential roles in ecosystem functioning and food webs and contributing to terrestrial invertebrate diversity once adults leave the riverine environment. Macroinvertebrates are essential prey for many indigenous fish and provide important food resources to support trout fisheries.
The Macroinvertebrate Community Index or MCI is a commonly used management tool to determine the aquatic health of a site, based on the presence or absence of enrichment tolerant or sensitive taxa. Ideally, the MCI should exceed 120 to support outstanding or regionally significant trout fisheries and exceed 100 to support other significant trout fisheries (Hay et al. 2006). These standards are likely to maintain healthy prey communities for indigenous fish species also and thereby maintain the life- supporting capacity of the river.
Ausseil (2009) found macroinvertebrate health (using the MCI) was less than expected for the upper catchment of the Ngaruroro at Kuripapango, based on Hawkes Bay Regional Council data. However, an assessment of MCI data collected monthly since 1990 for the National River Water Quality Network (NRWQN) shows that the median MCI is 130 with the mean MCI exceeding 130 (Fig. 1). These results indicate excellent water quality with no macroinvertebrate diversity limitation, adequate to support outstanding trout and indigenous fish values. The underlying cause of any discrepancies between the two macroinvertebrate datasets (HBRC and NIWA) is unknown but may be a result of methodological differences in sample collection, processing or identification. Median and mean MCI values for the Chesterhope site just exceed the recommended limit for the lower river fishery. However, this indicates that almost half of the time samples are below the limit and less than desirable to support the lower river fishery values. The reasons for decreased MCI at the Chesterhope site require further investigation. Trend analysis of MCI may determine whether lower MCI values are associated with increasing trends in nutrient enrichment.
The proportion of macroinvertebrate taxa that are within the EPT comprised of mayflies, stoneflies and caddis flies is another good indicator of the aquatic health of a site and the diversity of pollution tolerant taxa. EPT taxa make good, high energy, large sized prey items for fish and contribute to the diversity of terrestrial invertebrates once larvae emerge from rivers. Healthy numbers and diversity of these taxa support trout and indigenous fishes.
There is some decline in the proportion of EPT individuals between the Kuripapango and Chesterhope sites (Fig. 2a) and a substantial decrease in the diversity of species from upstream to downstream (Fig. 2b), indicating the presence of more pollution tolerant taxa at the downstream site.
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Figure 1. Macroinvertebrate Community Index (MCI) data for two sites on the Ngaruroro River collected annually between 1990 and 2012 as part of the National River Water Quality Network. Boxes contain 25th and 75th quartiles, whiskers are 10th and 90th percentiles and points are outliers. Medians are solid lines and dashed lines are means. Data courtesy of NIWA. a) b)
Figure 2. a) Proportion of EPT individuals and b) number of EPT taxa in macroinvertebrate samples collected from two sites in the Ngaruroro River between 1990 and 2012 as part of the National River Water Quality Network. Boxes contain 25th and 75th quartiles, whiskers at 10th and 90th percentiles and points are outliers. Medians are solid lines and dashed lines are means. Data courtesy of NIWA.
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4. Catchment Context and Threats
4.1 Water quality
Water quality in the upper River is measured by NIWA at Kuripapango as part of the National Rivers Water Quality Network (NRWQN) and in the lower river at Chesterhope Bridge. Water quality is outstanding at Kuripapango and the site ranked 2nd out of 76 for water clarity, low faecal indicator bacteria and overall suitability for contact recreation. That ranking dropped to 19th out of 76 for the Chesterhope Bridge site in the lower catchment (although the site ranks 9th in the country when only faecal indicator bacteria are considered). Kuripapango also ranked 5th for nutrient indicators and 2nd for biological health. For these categories Chesterhope ranked 32nd and 36th respectively, although the sites ranked 19th in the country for nitrate concentration. Despite the significant decline between the upper and lower catchment sites, water quality at Chesterhope is generally good relative to the lower reaches of many other large rivers in the country. The key water quality limitation in the Ngaruroro catchment is water clarity, which is often degraded below recreational guidelines at the Chesterhope site and is likely to have adverse impacts on aquatic biodiversity and recreational values.
Ausseil (2009) reported on water quality state, trends and contaminant loads in the Ngaruroro River catchment for Hawkes Bay Regional Council using Council monitored State of the Environment data and some NIWA data. Ausseil (2009) found that the only sites to exceed nutrient guidelines were the lower river tributaries (Waitio and Tutaekuri-Waimate) where phosphorus and nitrogen were problematic. Increasing phosphorus and nitrogen trends were found in some of the lower river mainstem sites although no trends were found at Chesterhope Bridge. An increasing nitrogen trend was also identified in the Waitio Stream.
According to Ausseil (2009) Hawke’s Bay Dairies, downstream of Whanawhana adds 2.5 tonnes per year of soluble phosphorus and in-river nitrogen loads double between upstream and downstream monitoring sites, adding an estimated 80 tonnes of soluble nitrogen per year.
Increasing nutrient enrichment is a concern as it can result in nuisance periphyton and algae in downstream receiving environments. Nuisance growths adversely impact aquatic ecosystem health and recreational and consumptive values (Biggs 2000). A brief analysis of data from the National Rivers Water Quality Network undertaken by the author specifically for the WCO application showed Kuripapango has never exceeded periphyton cover guidelines since monthly monitoring began in 1989. However, the Chesterhope Bridge site exceeded guidelines for filamentous algae eleven times during this period (when the ten observations taken at each sample were averaged). Increased periphyton cover is likely to be a major contributing factor to the reductions in macroinvertebrate community health measured at the Chesterhope site. Underlying causes of periphyton increase are most likely to be nutrient enrichment and longer periods of lower flows at the Chesterhope site.
The key water quality limitation in the Ngaruroro catchment is water clarity, which is often degraded below recreational guidelines at the Chesterhope site and is likely to have adverse impacts on the aquatic biodiversity, trout fishery and recreational values. Although increasing trends in nutrient concentrations are also of concern.
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4.2 Flows and Water Quantity
Low flows can be the conditions of greatest stress for many freshwater fish due to less available habitat, higher water temperatures and reduced dissolved oxygen. Minimum flows are set to maintain the minimum habitat for particular species and to ensure water takes do not decrease flows below this level during dry periods. Minimum flows are often set to maintain a proportion of habitat at the MALF2 for the most flow-demanding species or values, in the case of the Ngaruroro River this is the torrentfish.
The degree of allocation for out-of-river use affects how often and for how long minimum flows are reached. For example, as flows naturally recede during dryer months the larger the allocation the more water is taken and the sooner the minimum flow will be reached. If abstractions cease at the minimum flow the river may recover to above minimum flow levels, but if the allocation is large and taking of water resumes rapidly the minimum flow will again be reached. This creates a yo-yo effect in the hydrograph and keeps rivers at or near the minimum flow for longer periods than if the allocation were smaller. This has ecological effects, including elevated temperatures and reduction in dissolved oxygen saturation as well as loss of suitable habitat for some species. A balance is needed between the minimum flow and allocation limit to provide for aquatic life and river users.
The minimum flow set to maintain ecological, recreational and cultural values in the Regional Resource Management Plan (RRMP) for the Ngaruroro River at Fernhill is 2,400 litres/second. Johnson (2011) recommended a minimum flow to retain 90% of torrentfish habitat at the Mean Annual Low Flow (MALF) of 4,200 l/s. Harkness (2010) determined the naturalised 7-day MALF to be 5240 l/s at Fernhill. Current minimum flow provisions may not provide adequate retention of habitat for torrentfish during low flow events, particularly if abstractive pressure increases in the lower river. The degree of core allocation from a river determines how often and for how long a river is kept near of below the minimum flow. The RRMP allows for an allocation of 1,581 l/s from the Ngaruroro River.
Current allocation is more than twice the allocation limit outlined in the RRMP, although actual water use is less clear. The Glazebrooks and artificial recharge takes make up a large proportion of the allocation limit from the RRMP (~90%) although they make up only about 40% of the consented allocation from the river. The consented allocation is more than twice the limit set in the RRMP. Adverse effects on aquatic ecosystem values are likely if over-allocation and minimum flow inadequacies are not addressed. Additionally, this is likely to adversely affect the security of supply for water users. The current conservation status of torrentfish and other indigenous species requires a more precautionary approach and greater consideration of flow requirements in any future allocation or minimum flow setting.
4.3 Threats
There are a number of threats to freshwater values in the Ngaruroro River catchment. Threats are most relevant in the lower river, where intensification of resource use and concomitant increases in contaminants and abstractive pressures are most likely. Nutrient enrichment is a concern for lowland rivers throughout New Zealand (Ballantine et al. 2012). Although nutrient concentrations and loads are currently within guideline values for the Ngaruroro, trends show increasing nitrogen and phosphorus
2 MALF = Mean Annual Low Flow.
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are occurring in the lower river and at least two tributaries. Effects of increasing enrichment are apparent in biomonitoring results (i.e. periphyton and macroinvertebrate communities). These trends should be monitored closely and management of nutrient inputs from all sources should be considered if increasing trends continue. Poor water clarity in the lower catchment is also of concern. Efforts to identify and control inputs contributing to reduced clarity should be a key management action for the river.
The generally good state of water quality in the Ngaruroro is one of the key factors contributing to the river’s outstanding values and is an outstanding value in its own right. Degradation of water quality over time has the potential to threaten and erode values.
In addition to threats from degrading water quality, maintaining flow and habitat variability are important factors to supporting a healthy and diverse freshwater fauna. The braided reaches of the river naturally contains diverse habitats suited to a range of indigenous fish (e.g. high velocity areas for torrentfish, koaro and smelt and low-flow backwater areas for bullies and dwarf galaxids). Maintaining the integrity of the braided reach habitat is a management priority for the lower river. Future minimum flow and allocation regimes should consider maintenance of diverse habitats and protection of significant flow-demanding species such as torrentfish.
Habitat and flow requirements need to be accounted for throughout the mainstem to provide for the diadromous nature of many of the species present. The assumption that incoming larval migrants will be recruited from other catchments in the surrounding Hawkes Bay area is risky, given the abstraction pressures common to many rivers in the region (Johnson 2011). In all likelihood the good water quality and outstanding habitat of the Ngaruroro River provides a reservoir of larval recruits to other near-by catchments, the potential value of the river to the wider aquatic biodiversity of the Region warrants further investigation.
Other threats to freshwater fauna in the Ngaruroro include potential for loss of estuarine spawning habitat (through grazing of marginal vegetation or land development and modification), loss of access to the sea through river mouth closure during critical migration periods, fish barriers throughout the catchment, fish entrainment in irrigation intake structures and races, and the impact of pest fish such as Gambusia sp. Clarification and management planning to address these threats in relation to the maintenance and protection of the outstanding values of the catchment is required.
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5. Summary
The Ngaruroro River catchment holds a number of outstanding freshwater values associated with indigenous fish communities and habitat. These values are largely found throughout the mainstem of the river. In addition to the significant features of the lower river described in this report, the high water quality in the catchment and the lower river habitat provides support for outstanding features in the braided and upper river reaches. In summary, the outstanding native fish values of the Ngaruroro River worthy of a Water Conservation Order include:
Whole catchment - source to sea
Highly diverse freshwater fish fauna with a high proportion of at risk and declining indigenous freshwater species. Longfin eel and torrentfish habitat throughout the mainstem from source to sea.
Upper river - including tributaries (upstream of Whanawhana)
An upper river catchment with an abundance of at risk and declining indigenous species, in particular longfin eel, koaro, torrentfish and koura (freshwater crayfish).
Lower river: braided reach (Whanawhana to Fernhill)
High aquatic habitat diversity (braided channel) in combination with outstanding water quality supporting a diverse fauna of indigenous fish. 60% of species recorded in this reach are considered at risk and declining. Outstanding populations of Northern dwarf galaxias and torrentfish. High diversity of Gobiomorphus (bully) taxa, including at risk and declining species (bluegill and redfin bully). This reach has the highest diversity of indigenous fish recorded in the Ngaruroro despite low sampling effort.
Lower river: flood control reach (Fernhill to Chesterhope)
Dwarf galaxias and torrentfish habitat. Suitable habitat, water quality and flow to provide a physical link between upstream reaches and the sea. Improvement or maintenance of the habitat, water quality and flow values in the flood control reach is critical to support outstanding migratory freshwater fish values upstream. Poor water clarity, minimum flow regimes and increasing nutrient trends are a concern for the continuation of outstanding values throughout the river.
Lower river: estuary (Chesterhope to sea)
High indigenous fish diversity in the estuary, including the reach below Chesterhope. Inanga spawning and estuarine/marine nursery habitat within the estuary proper.
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Suitable habitat, water quality and flow to provide physical links between upstream reaches and the sea. Improvement or maintenance of the habitat, water quality and flow values in the estuary reach is critical to support outstanding migratory freshwater fish values upstream.
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6. References
Allibone R, David B, Hitchmough R, Jellyman D, Ling N, Ravenscroft P, Waters J 2010. Conservation status of New Zealand freshwater fish, 2009. New Zealand Journal of Marine and Freshwater Research 44: 271 287.
Ausseil 2009. Water Quality in the Ngaruroro Catchment: State, Trends and Contaminant Loads. Report prepared for Hawkes Bay Regional Council by Aquanet Consulting Limited.
Ballantine D, Booker D, Unwin M, Snelder T 2010. Analysis of national river water quality data for the period 1998 - 2007. Report prepared for the Ministry for the Environment. NIWA Client Report CHC2010-038.
Biggs B 2000. New Zealand Periphyton Guidelines: Detecting, Monitoring and Managing Enrichment of Streams. Ministry for the Environment, Wellington, New Zealand.
Cameron F 2008. Wetland Monitoring Review: A review of Hawkes Bay Regional Councils’ Wetland Monitoring. Environmental Management Technical Report. HBRC Plan No. 4076.
Harkness M 2010. Ngaruroro River flow naturalisation. Prepared for Hawkes Bay Regional Council by MWH.
Hay J, Hayes J, Young R 2006. Water Quality Guidelines to Protect Trout Fishery Values. Report prepared for Horizons Regional Council. Cawthron Report No 1205.
Johnson K 2011. Lower Ngaruroro Instream Minimum Flow Assessment. Hawkes Bay Regional Council Environmental Management Group Technical Report. HBRC Plan No 4249.
Jowett IG, Richardson J 1996. Distribution and abundance of freshwater fish in New Zealand rivers. New Zealand Journal of Marine and Freshwater Research 30: 239-255.
Jowett IG, Richardson J 2008. Habitat use by New Zealand fish and habitat suitability models. NIWA Science and Technology Series No 55. 148 p.
Joy MK, Death RG 2001. Control of freshwater fish and crayfish community structure in Taranaki, New Zealand: dams, diadromy or habitat structure? Freshwater Biology 46: 417-429.
McDowall RM 2001. Freshwater fishes of New Zealand. Reed New Zealand Nature Series. Auckland, New Zealand.
Townsend AJ, de Lange PJ, Duffy CAJ, Miskelly CM, Molloy J, Norton D 2008. New Zealand threat classification manual. Wellington, Department of Conservation. http://www.doc.govt.nz/upload/documents/science-and-technical/sap244.pdf
Walls G 2005. Waitangi Estuary Ecological Monitoring 2004. Environmental Management Technical Report. HBRC Plan No. 3748.
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Appendix 1: List of data sources3
Reference Type of Data Ngaruroro River Flood Protection and Drainage Scheme Ecological Chapter 2: River Values provides a concise summary of the fish records, fish Management and Enhancement Plan. Report prepared for distribution and water quality as well as locations of wetlands and other ecological Hawke’s Bay Regional Council by MWH features. Available on request from Hawkes Bay Regional Council Cameron, F. 2008. Wetland Monitoring Review: A review of Context around Lakes Runanga and Oingo eel fishery and Waitangi Estuary inanga Hawkes Bay Regional Councils’ Wetland Monitoring. spawning (and RAP designations). Environmental Management Technical Report. HBRC Plan No. 4076 http://www.hbrc.govt.nz/Hawkes-Bay/Projects/Pages/tank-reports.aspx Walls, G. 2005. Waitangi Estuary Ecological Monitoring 2004. Identifies fish species in the estuary monitoring and identifies the estuary as Environmental Management Technical Report. HBRC Plan No. containing regionally significant fish values. 3748 http://www.hbrc.govt.nz/HBRC- Documents/HBRC%20Document%20Library/3748%20EMI%200503%20Waitangi%20Estuary%20Ecological%20Monitoring%202004.pdf Ausseil 2009. Water Quality in the Ngaruroro Catchment: State, Water quality, land use and flow statistics for a number of sites in the Ngaruroro Trends and Contaminant Loads. catchment. Compiled from information from HBRC and NIWA. Biomonitoring and periphyton data included. Recommended water quality standards and guidelines for the catchment. http://www.hbrc.govt.nz/HBRC- Documents/HBRC%20Document%20Library/Water%20Quality%20in%20the%20Ngaruroro%20catchment%20State%20trends%20and%20contaminant%20l oads%20Aquanet%20consulting%20Sept%202009.pdf
3 Water quality, biomonitoring, flow and freshwater fish records and data from the National River Water Quality Monitoring Network and the NZ Freshwater Fish Database provided electronically in Excel workbooks. All data courtesy of NIWA under a data use agreement specifically for the Ngaruroro Water Conservation Order project.
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Jowett and Richardson 2008. Habitat use by New Zealand fish and Habitat suitability curves and flow requirements for NZ native fish species habitat suitability models. NIWA Science and Technology Report No. 55. 148 p. Available online from www.jowettconsulting.co.nz Johnson K. 2011. Lower Ngaruroro instream flow assessment. Identifies minimum flows and naturalised flows in relation to rainbow trout and native Hawkes Bay Regional Council Environmental Management Group fish. Particular references to the high flow requirements of torrentfish. Identifies ideal Technical Report. HBRC Plan No 4249 minimum flows are higher than minimum flows in RRMP and current low flow regimes in the lower river. Identifies proportion of minimum flows in relation to the mean annual low flow for the major rivers in the Hawkes Bay Region. http://www.hbrc.govt.nz/HBRC- Documents/HBRC%20Document%20Library/4249%20EMT%201038%20Lower%20Ngaruroro%20River%20Instream%20Flow%20Assessment.pdf Harkness M. 2010. Ngaruroro River Flow Naturalisation. Prepared Naturalised flow statistics for the Ngaruroro River at Fernhill. Accounting of for Hawkes Bay Regional Council by MWH. abstracted volumes for the Ngaruroro. http://www.hbrc.govt.nz/HBRC- Documents/HBRC%20Document%20Library/Harkness,%20M%202010,%20Ngaruroro%20River%20Flow%20Naturalisation.pdf Harkness M. 2010. Ngaruroro River High Flow Allocation June to Useful summary of RRMP provisions and naturalised flow statistics (including FRE3) in November Period. Prepared for Hawkes Bay Regional Council by relation to the Ngaruroro and bibliography for references purposes. Summary of MWH. migratory timing for 17 fish species. http://www.hbrc.govt.nz/hbrc- documents/hbrc%20document%20library/harkness,%20m%202010,%20ngaruroro%20river%20high%20flow%20allocation%20june%20to%20november%2 0period.%20prepared%20for%20hb,%20mwh,%20wellington.pdf
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