NZ Forest and Bird Protection Society · Unidentified salmonid n/a possibly ... protection of spawning areas should be considered a priority for viable species maintenance in the

NZ Forest and Bird Protection Society

Assessment of Outstanding Freshwater Fish Values on the

Ngaruroro River

Kate McArthur

May 2013

page 1 Assessment of Outstanding Freshwater Fish Values on the Ngaruroro River

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.


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.


Table 2. Conservation threat status, migration and location of fish and koura species recorded in the Ngaruroro River and its tributaries.

Common name Conservation status1

Mig

rato

ry

Up

per

Riv

er

Bra

ided

rea

ch

Flo

od

co

ntr

ol

reac

h

Estu

ary

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 triplefin Not threatened

marine

Inanga At risk - declining

Koaro At risk - declining Lamprey / piharau / kanakana

At risk - declining

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.


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.


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.


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.


Map 1. New Zealand Freshwater Fish Database records for the Ngaruroro River catchment (n = 160). Survey data collected between 1986 and 2011.


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.


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.


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.


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.


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.


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.


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.


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.

http://www.doc.govt.nz/upload/documents/science-and-technical/sap244.pdf


Appendix 1: List of data sources3

Reference Type of Data

Ngaruroro River Flood Protection and Drainage Scheme Ecological

Management and Enhancement Plan. Report prepared for

Hawke’s Bay Regional Council by MWH

Chapter 2: River Values provides a concise summary of the fish records, fish

distribution and water quality as well as locations of wetlands and other ecological

features.

Available on request from Hawkes Bay Regional Council

Cameron, F. 2008. Wetland Monitoring Review: A review of

Hawkes Bay Regional Councils’ Wetland Monitoring.

Environmental Management Technical Report. HBRC Plan No.

4076

Context around Lakes Runanga and Oingo eel fishery and Waitangi Estuary inanga

spawning (and RAP designations).

http://www.hbrc.govt.nz/Hawkes-Bay/Projects/Pages/tank-reports.aspx

Walls, G. 2005. Waitangi Estuary Ecological Monitoring 2004.

Environmental Management Technical Report. HBRC Plan No.

3748

Identifies fish species in the estuary monitoring and identifies the estuary as

containing regionally significant fish values.

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, Trends and Contaminant Loads.

Water quality, land use and flow statistics for a number of sites in the Ngaruroro 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%20loads%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.


Jowett and Richardson 2008. Habitat use by New Zealand fish and habitat suitability models. NIWA Science and Technology Report No. 55. 148 p.

Habitat suitability curves and flow requirements for NZ native fish species

Available online from www.jowettconsulting.co.nz

Johnson K. 2011. Lower Ngaruroro instream flow assessment. Hawkes Bay Regional Council Environmental Management Group Technical Report. HBRC Plan No 4249

Identifies minimum flows and naturalised flows in relation to rainbow trout and native fish. Particular references to the high flow requirements of torrentfish. Identifies ideal 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 for Hawkes Bay Regional Council by MWH.

Naturalised flow statistics for the Ngaruroro River at Fernhill. Accounting of 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 November Period. Prepared for Hawkes Bay Regional Council by MWH.

Useful summary of RRMP provisions and naturalised flow statistics (including FRE3) in relation to the Ngaruroro and bibliography for references purposes. Summary of 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%20period.%20prepared%20for%20hb,%20mwh,%20wellington.pdf