V 1.01
V 1.02
Clinton Duffy
Dave Allen
5/12/14
22/12/14
Original
Incorporated
Biosecurity
comments, references, minor
edits
Biodiversity and Biosecurity
Summary of Information
Contents
1
2
3
Context .......................................................................................................................... 2
1.1
Purpose of the SeaChange Project ......................................................................... 2
1.2
Biodiversity and Biosecurity Roundtable Scope ...................................................... 2
1.3
The Hauraki Gulf Marine Ecosystem ....................................................................... 3
Biodiversity Values ......................................................................................................... 6
2.1
Protected Species ................................................................................................... 6
2.2
Threatened Species ................................................................................................ 7
2.3
Sites of international Significance ........................................................................... 9
2.4
Sites of National Significance ................................................................................ 10
2.5
Threatened Habitats ............................................................................................. 11
Threats to Biodiversity.................................................................................................. 11
3.1
Key issues identified in the State of Our Gulf Report 2014 .................................... 11
3.2
Global Climate Change ......................................................................................... 14
3.2.1
Sea-level rise predictions ............................................................................... 14
4
Marine Protected Areas ............................................................................................... 17
5
Biosecuirty ................................................................................................................... 20
6
References .................................................................................................................. 22
1
1 Context
1.1 Purpose of the SeaChange Project
The Sea Change project aims to develop a spatial plan that will achieve sustainable
management of the Hauraki Gulf, including a Hauraki Gulf that is vibrant with life and healthy
mauri, is increasingly productive and supports thriving communities. It aims to provide
increased certainty for the economic, cultural and social goals of our community and ensure
the ecosystem functions that make those goals possible are sustained.
The spatial plan will provide guidance and vision for the sustainable management of the
Hauraki Gulf, including locations set aside for various human related activities, and areas for
protection of the natural environment (Sea Change Stakeholder Working Group terms of
reference).
1.2 Biodiversity and Biosecurity Roundtable Scope
The roundtable covers two large distinct but not unrelated topics: biodiversity and
biosecurity. The following is to be considered within scope for roundtable discussion.
Biodiversity:
1. Understanding the current state and threats to biodiversity
2. Reduce, remove, mitigate and safeguard against threats to biodiversity
3. Ecosystem based approach to replenish and revive our Gulf
Biosecurity:
Identify, manage and mitigate biodiversity threats (freshwater, marine & terrestrial)
including:
1.
2.
3.
4.
Shipping, boating, barging and other modes of sea transport
Fishing, aquaculture
Dredging/dumping activity
Introduced materials/products/produces/species
Definiton of Biodiversity:
The variety of plant and animal life in the Hauraki Gulf.
Definition of Biosecurity:
Biosecurity is the exclusion, eradication or effective management of risks posed
by pests and diseases to the economy, environment and human health (Tiakina
Aotearoa Protect New Zealand The Biosecurity Strategy for New Zealand August
2003)
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1.3 The Hauraki Gulf Marine Ecosystem
The Hauraki Gulf Marine Park is situated within the north eastern coastal marine bioregion
(Department of Conservation & Ministry of Fisheries 2011). This coastal bioregion covers
the northeast and a small part of the northwest coasts of North Island, between Ahipara and
East Cape. The marine flora and fauna of this region is strongly influenced by the flow of
subtropical water derived from the East Australian Current (EAC) across the Tasman Sea
and its reattachment to the New Zealand shelf as the East Auckland Current (EAUC). This
flow brings larval and juvenile stages of subtropical and tropical species to the northeast
shelf, resulting in elevated diversity of all forms of coastal marine life (Francis et al. 1999;
Sutton & Roemmich 2001; Beaumont et al. 2008; Shears et al. 2008). It is this mixture of
subtropical and tropical species and widespread temperate species that distinguishes the
northeast North Island from all other New Zealand coastal bioregions (Francis 1996; Shears
et al. 2008).
Most of the Hauraki Gulf Marine Park is situated over the continental shelf, with only a small
area of the upper continental slope occurring within the park’s seaward boundary east of
Coromandel Peninsula. Shelf sediments are predominantly terrigenous (i.e. derived from
terrestrial environments), although there are localised areas of calcareous sediments
(formed from the shells and skeletons of marine organisms) associated with biogenic
habitats in shallow bays and areas of high tidal flow. Extensive shallow rocky reefs occur
around much of the coastline, except in the Firth of Thames which is dominated by soft
sediments, particularly muds. Deep rocky reefs are located on the outer shelf northeast of
Mokohinau Islands, east of Great Barrier Island and Coromandel Peninsula and west of Little
Barrier Island.
Pelagic biological productivity throughout the marine park is strongly influenced by seasonal
and interannual variation in the East Auckland Current (EAUC) (Stanton & Sutton 2003).
The EAUC originates northeast of North Cape and flows south-east along the upper
continental slope. A large-scale permanent warm core eddy (North Cape Eddy) extending to
1500 m depth is located offshore of the EAUC. This eddy re-circulates about 50% of the
flow in the EAUC and probably serves as a larval retention mechanism (Roemmich & Sutton
1998). The EAUC-North Cape Eddy system is highly variable. Much of this variation is
attributed to variation in the position, configuration and magnitude of the core of the North
Cape Eddy (Stanton & Sutton 2003). Temperature variability in the surface mixed layer of
the EAUC is dominated by the annual cycle, with differences between years highly
correlated with the Southern Oscillation Index (a measure of the strength of the El NiñoSouthern Oscillation climate phenomenon) and wind speed and direction (Sutton &
Roemmich 2001). The EAUC is forced towards the surface over the upper continental slope,
and upwelling caused by along-shelf winds transports nutrients, particularly nitrate, onshore
making this one of New Zealand’s most productive shelf regions (Sharples & Greig 1998;
Zeldis et al. 2001, 2004; Zeldis 2004; Bradford-Grieve et al. 2006).
Circulation over the inner continental shelf is dominated by tides, local winds and the
southeast flow of the EAUC (Sharples & Greig 1998; Stephens 2003). Episodic upwelling of
slope water onto the shelf and into Hauraki Gulf during autumn and winter is driven by alongshelf winds blowing towards the southeast. Because upwelling and downwelling are wind
driven the strength of each varies with wind strength and direction. The El Niño phase of the
Southern Oscillation favours upwelling, whereas La Niña favours downwelling and
suppresses phytoplankton production (Zeldis et al. 2001, 2004, 2005; Chang et al. 2003;
Zeldis 2004; Bradford-Grieve et al. 2006; Hall et al. 2006). During spring and summer
stratification de-couples the surface layer from the rest of the water column and shuts down
3
upwelling. Stratification results in nutrient depletion of the upper water column by
phytoplankton but an internal tide present in summer has capacity to mix nutrients across
the pycnocline and drive sub-surface production (Sharples & Greig 1998; Hall et al. 2006).
In contrast to the outer Hauraki Gulf circulation and productivity in the Firth of Thames are
strongly catchment driven. Freshwater inflow, tides and local winds exert a strong influence
on the flow in the Firth of Thames (Stephens 2003; Oldman et al. 2007; Hadfield et al. 2014).
The Waihou, Piako and Kaueranga rivers input significant amounts of freshwater, sediments
and nutrients into the Firth of Thames, resulting in strong vertical and horizontal gradients in
salinity, suspended sediments and nutrients (Hadfield et al. 2014).
High concentrations of fish eggs and larvae have been recorded over the shelf in a number
of places consistent with the observed high primary productivity (Crossland 1981; Bailey
1983; Zeldis et al. 2005). Crossland (1981) recognized three patterns of spawning in Hauraki
Gulf: those species where spawning was concentrated in the Firth of Thames (e.g. ahuru,
flatfishes), those that spawned in the inner (‘central’) Gulf (e.g. anchovy, sprat, jack
mackerel, yellow eyed mullet, snapper) and those that had spawning grounds located in the
outer Gulf (e.g. pilchards, red gurnard, blue mackerel). The inner Hauraki Gulf is an
important spawning area for snapper, with spawning aggregations concentrated in
Whangaparaoa Bay, between Rangitoto Island and Whangaparaoa Peninsula, and between
Waiheke Island and Coromandel Peninsula. Snapper spawning has also been documented
southwest of Great Barrier Island (Zeldis & Francis 1998; Zeldis et al. 2005).
Phytoplankton blooms in spring and early summer support a relatively high biomass of large
zooplankton (particularly euphausiids, hyperid amphipods, salps, siphonophores, pteropods)
that in turn supports a variety of squids, a resident fish community consisting of about 13
species, and a highly migratory fish community of about 15 sub-tropical and tropical species
(Bailey 1983). The resident fish community includes several mesopelgic fishes as well as
small epipelagic species (anchovies, pilchards, saury) that are important in the diets of large
predatory fishes, seabirds and cetaceans. The migratory fish community includes a variety of
pelagic sharks, rays, billfishes and tunas. The latter include commercially important species
such as skipjack and albacore. These highly migratory species are mainly present during
summer and appear to follow the 20oC isotherm from tropical regions to northern New
Zealand (Bailey 1983). Records of protected whale shark (Rhincodon typus), spine-tailed
devil ray (Mobula japanica) and giant manta (Manta birostris) are concentrated along the
shelf break during summer, particularly between northeast Great Barrier Island and Cape
Brett (Paulin et al. 1982; Bailey 1983; Duffy 2002; Duffy & Abbott 2003; Francis & Lyon
2012; Jones & Francis 2012).
The cetacean fauna of the region is relatively diverse and includes southern right whale,
humpback whale, blue whale, Bryde’s whale, sei whale, minke whale, common dolphin,
striped dolphins (Stenella coeruleoalba), bottlenose dolphin, killer whale, false killer whales,
long-finned pilot whale and a variety of beaked whales (Baker 1983; Visser 2000; Baker &
Madon 2002; Constantine 2002; O’Callaghan & Baker 2002; Stockin et al. 2008; Visser et al.
2010; Wiseman et al. 2011; Zaeschmar et al. 2012). Resident species are Bryde’s whale,
common dolphin, bottlenose dolphin and killer whale. Bryde’s whales are concentrated in
inner Hauraki Gulf, with smaller clusters of sightings off Cape Brett, Cape Karikari and in the
vicinity of Parengarenga Canyon (Baker & Madon 2002; O’Callaghan & Baker 2002;
Wiseman et al. 2011). Common dolphins are widespread but there is some evidence that
Hauraki Gulf provides important foraging and nursery habitat for this species (Stockin et al.
2013). Genetic evidence shows there is little or no connectivity between the Northeast North
Island and other coastal bottlenose dolphin populations but population structure within
Northeast North Island is unclear (Tezanos-Pinto 2009; Tezanos-Pinto et al. 2009). There is
evidence of movement of bottlenose dolphins between Hauraki Gulf, Bay of Islands and
elsewhere in Northland, as well as changing habitat use in the Bay of Islands (Constantine
4
2002; Berghan et al. 2008; Tezanos-Pinto 2009; Tezanos-Pinto et al. 2013). The
significance of the region to endangered southern right whales is unknown. Recent sightings
of right whales in Hauraki Gulf have involved mother-calf pairs suggesting the species may
have once used the Gulf as a nursery habitat. Humpback whales migrate through the region
apparently without feeding. However dwarf minke and blue whales have both been observed
feeding on euphausiid swams in Hauraki Gulf (Gaskin 1968; Dawbin 1988; Garrigue et al.
2010; Torres et al. 2013; C. Duffy. pers. obs.). Long-finned pilot whales, false killer whales
and beaked whales are most frequently encountered over the outer shelf and upper slope,
probably reflecting the importance of squids in their diet. Long-finned pilot whales can be
particularly abundant in this habitat and sometimes form mixed pods with large bottlenose
dolphins. Groups of New Zealand fur seals are sometimes encountered along the shelf
break (C.Duffy. pers. obs.).
The combination of high pelagic productivity and numerous predator-free islands makes the
entire North Eastern Marine Bioregion, particularly the area between Cape Brett and Waihi,
including Hauraki Gulf, a globally significant seabird biodiversity hotspot (Gaskin & Rayner
2012). Large seabird nesting colonies occur on predator-free offshore islands, with more
resilient species breeding at scattered mainland locations. The total number of seabird taxa
breeding in the region is 27 of which 16 (59 %) are New Zealand endemics, and 4 (14.8%)
are regional endemics (Gaskin & Rayner 2013). The latter are the New Zealand fairy tern
(Sternula nereis davisae), Pycroft’s petrel (Pterodroma pycrofti), black petrel (Procellaria
parkinsoni) and New Zealand storm petrel (Fregetta maoriana) (Gaskin & Rayner 2013).
Benthic primary production within Hauraki Gulf is limited by depth and water clarity. Kelp
forests on rocky reefs contribute large amounts of particulate and dissolved organic matter to
coastal ecosystems. These extend to a maximum depth of about 40 m in clear outer Gulf
waters, shallowing to less than two metres depth in the inner Gulf and Firth of Thames. On
soft sediments benthic primary production involves sea grass, attached macroalgae
(primarily small red and green seaweeds) and microphyton (single celled photosynthethic
organisms). Declining water quality and disturbance of seafloor (removal of macrophytes
and loss of bioturbaters) over large parts of the Gulf implies there has been major reduction
in benthic primary production over time. Combined with the loss of biogenic habitats and the
associated epifauna there is likely to have been a major decline in total benthic production.
This could have significant implications for fisheries production through trophic cascades and
loss of critical habitats for vulnerable life-history stages.
Outer shelf and upper slope habitats are poorly known but some deep offshore reef systems
are known support diverse invertebrate assemblages including protected coral species
(particularly gorgonians and antipatharians). A trawl survey conducted off the northeast
North Island in the mid-1980s recorded moderate demersal fish diversity, with hoki, ling,
shovelnose dogfish and orange roughy predominating from 400-1000 m. Lantern fishes,
squids and salps predominanted in midwater trawls (Clark & King 1989). Frost fish are
common and spawn over the upper slope, their eggs forming part of the diet of some pelagic
species (Bailey 1983).
Significant examples of examples of indigenous coastal wetland and saltmarsh vegetation
occur in Manaia Harbour, Coromandel Harbour (south side of Preece Point), Colville Bay,
Whangapoua Harbour, Tairua, Waharekawa and Whangamata Harbours, as well as a
number of sites around the coastline of Great Barrier Island. The small estuary on
Whangapoua Creek, Great Barrier Island is notable for intact indigenous coastal vegetation
sequences and a remnant subtidal green-lipped mussel reef (formerly a widespread habitat
type in Hauraki Gulf). Nationally and internationally important wading and shore bird
habitats occur in the Firth of Thames and in Tairua, Wharekawa and Whangamata Harbours.
The Firth of Thames is an internationally important feeding area for wading birds, with up to
25,000 mostly migratory species using it at any time. It is listed as a wetland of international
5
importance under the Ramsar Convention, and is ranked as one of New Zealand's three
most important wading bird habitats. Waitemata Harbour, Coromandel Harbour, Colville Bay,
Whangapoa Harbour and Whitianga Harbour contain regionally important wading and shore
bird habitat. Subtidal sea grass (Zostera muelleri) beds are a nationally rare habitat-type
that occurs at Great Mercury Island, Slipper Island and in Whangapoa Harbour, Coromandel
Peninsula. Elsewhere this habitat type is only known from Parengarenga, Houhora and
Rangaunu Harbours and the Bay of Islands (Urupukapuka Island).
2 Biodiversity Values
2.1 Protected Species
A relatively large number of protected marine and coastal species occur in the Hauraki Gulf
Marine Park.
Marine invertebrates and fishes protected under Schedule 7A (Marine species declared to
be animals) of the Wildlife Act 1953 include:
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all hydrocorals (family Stylasteridae, includes the red corals), black corals (order
Antipatharia), gorgonians (order Gorgonacea) and stony corals (order Scleractinia);
some stony corals, notably Flabellum spp. and the small colonial cup coral Culicia
rubeola, are common on shallow coastal reefs throughout the Gulf, whereas the
occurrence and distribution of the larger, habitat-forming deepwater species is poorly
known in the Gulf; black corals and gorgonians are common on some deep (>40 m
depth) reefs off northeast GBI and are likely to occur in similar habitats throughout
the outer Gulf
great white shark (white pointer, white shark) – naturally uncommon, found
throughout the Hauraki Gulf Marine Park, some breeding may occur in the inner Gulf
whale shark – regular summer visitor, usually seen over the outer shelf and upper
continental slope (off Mokohinau Islands, Great Barrier Island and eastern
Coromandel Peninsula)
basking shark - rare, only two historical records from the inner Gulf (Kawau Island,
Firth of Thames)
giant manta ray – regular summer visitor, seen over the outer shelf and off some of
the Gulf islands, particularly Mokohinau, Little Barrier and Great Barrier Islands
spine-tailed devil ray – regular summer visitor, usually encountered offshore beyond
the shelf break
spotted black grouper – uncommon, found on shallow rocky reefs to about 30 m
depth
giant grouper (Queensland grouper) – very rare, occasionally seen on shallow rocky
reefs, the only records from the Hauraki Gulf Marine Park are from the Alderman
Islands.
All indigenous sea birds and shore birds are protected under the Wildlife Act 1953. About 72
species of seabird have been recorded from the Hauraki Gulf, this represents about 20% of
seabirds globally. Of these, 27 species breed in the Gulf (31% of New Zealand seabird
fauna, 59% endemic to New Zealand). Notable species include the black petrel (the entire
global population breeds on GBI and LBI), Pycroft’s petrel (global population breeds on
Mercury, Cuvier, Hen and Chickens and Poor Kinghts Islands), Cook’s petrel (96% of the
global population breeds on LBI), New Zealand storm petrel (thought to be extinct until 2003,
6
global population breeds on LBI), New Zealand fairy tern (global population breeds on
Mangawhai, Pakiri and Waipu beaches), and Hutton’s shearwater (forages in the Gulf, global
population breeds on Poor Knights Islands). Burgess Island, Mokohinau Islands, supports
one of most diverse seabird breeding assemblages in New Zealand.
At least 77 shore bird species occur in the Hauraki Gulf Marine Park. They include some of
the most endangered bird species in New Zealand. The Firth of Thames RAMSAR site is an
internationally significant shorebird habitat however many of the smaller estuaries and
harbours provide critical habitat for species such as New Zealand fairy tern, New Zealand
dotterel and New Zealand shore plover.
All marine mammals are protected under the Marine Mammals Protection Act 1971. A total
of 20 species of cetaceans are recorded from the Hauraki Gulf Marine Park. The commonest
species are bottlenose dolphins, common dolphins, killer whales and Bryde’s whales.
Transient species, including regular seasonal migrants, are the southern right whale,
humpback whale, sei whale, blue whale, beaked whales (particularly Gray’s beaked whale),
pilot whale and false killer whale. New Zealand fur seals are the only pinniped regularly
seen in the Gulf. Leopard seals are occasional seasonal (winter) visitors.
2.2 Threatened Species
This section lists marine and estuarine species occurring in the Hauraki Gulf Marine Park
according to their conservation status. The New Zealand threat classification system
(NZTCS) assessment is given for species considered resident or breeding in New Zealand
(Townsend et al. 2008; Baker et al. 2010; Freeman et al. 2010; Robertson et al. 2013;
Goodman et al. 2014). Species assessed as Not Threatened in New Zealand are not listed.
The IUCN Red List of Threatened Species status is given for migrant, vagrant and colonising
marine fishes and cetaceans occurring in, or migrating through the waters of the marine park
(http://www.iucnredlist.org/). These species are not assessed by the NZTCS (Townsend et
al. 2008).
Nationally Critical
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Black-billed gull
New Zealand fairy tern
New Zealand shore plover
Bryde’s whale
Killer whale
Nationally Endangered
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Australasian bittern
Reef heron
New Zealand storm petrel
Southern right whale
Bottlenose dolphin
Nationally Vulnerable
 Lamprey
 Shortjaw kokopu
 Wrybill
7
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Lesser knot
Banded dotterel
Northern New Zealand dotterel
Caspian tern
Red-billed gull
Pied shag
Black petrel
Flesh-footed shearwater
At Risk, Declining
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Great white shark
Basking shark
Longfinned eel
Giant kokopu
Koaro
Inanga
Bluegill bully
Redfin bully
Torrentfish
Northern blue penguin
Banded rail
Pied stilt
Eastern bar-tailed godwit
White-fronted tern
At Risk, Recovering
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Brown teal
Variable oystercatcher
Pycroft’s petrel
North Island little shearwater
At Risk, Relict
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Fairy prion
New Zealand white-faced storm petrel
Northern diving petrel
Cook’s petrel
Spotless crake
Fluttering shearwater
At Risk, Naturally Uncommon
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Black coral (Lillipathes lilliei)
Spider crab (Leptomithrax tuberculatus mortenseni)
New Zealand lancelet (Epigonichthys hectori)
Spotted black grouper
Buller’s shearwater
8
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Black shag
Little black shag
Migrant
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Whale sharks – IUCN Red List status: Vulnerable, population trend decreasing
Giant manta ray – IUCN Red List status: Vulnerable, population trend decreasing
Spinetailed devil ray – IUCN Red List status: Near Threatened, population trend
unknown
Blue whale – IUCN Red List status: Endangered, population trend: increasing
Sei whale – IUCN Red List status: Endangered, population trend: unknown
Vagrant / Coloniser
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Giant grouper (Queensland grouper) – IUCN Red List status: Vulnerable, population
trend decreasing
Data Deficient

Black pipefish (Stigmatopora nigra)
The spider crab Leptomithrax tuberculatus mortenseni has a restricted range and appears to
be a habitat specialist. It is only known from sponge and bryozoan dominated habitats on
the inner shelf (10-100 m depth) off the northeast North Island (Cape Maria van Diemen to
the Hauraki Gulf) and the Kermadec Islands (McLay 1988). It is potentially threatened by
habitat loss caused by intensive fishing and/or sedimentation (McLay, 1994; Ministry for the
Environment, State of New Zealand’s Environment 1997, The State of Our Invertebrate
Animals http://www.mfe.govt.nz/publications/ser/ser1997/html/chapter9.7.2.html). The New
Zealand lancelet (Epigonichthys hectori) is a small, poorly known chordate that inhabits
shallow, coarse clean sandy substrata off the northeast North Island and in Croisilles
Harbour, Marlborough Sounds. It is potentially threatened by habitat loss caused by
sedimentation, and possibly disturbance caused by shellfish dredging. It is reported to be
abundant in Omaha Bay (Taylor & Morrison 2008). The black pipefish (Stigmatopora nigra)
is a poorly known inshore species that appears to occur most abundantly in subtidal
seagrass beds.
2.3 Sites of international Significance
The North Eastern Marine Bioregion, particularly the area between Cape Brett and Waihi,
including Hauraki Gulf, is a globally significant seabird biodiversity hotspot (Gaskin & Rayner
2012). Of particular signifincance are the islands supporting breeding populations of national
and regional endemic species.
RAMSAR Sites
The Convention on Wetlands of International Importance, called the RAMSAR Convention,
is an intergovernmental treaty that provides the framework for national action and
international cooperation for the conservation and wise use of wetlands and their resources.
9
Six RAMSAR sites are recognised in New Zealand, they are Awarua Wetland, Farewell Spit,
Manawatu River mouth and estuary, Whangamarino, Kopuatai Peat Dome and Firth of
Thames. The Firth of Thames is renowned for its populations of migratory wading birds
reflecting the combination of abundant of food, mainly intertidal shellfish and polychaete
worms, and safe high-water coastal roosts. Seventy-seven species of shorebirds have been
recorded from the site, with up to 25,000 mostly migratory waders using it at any time (Hay
1983; Battley & Brownell 2007). Long-term monitoring (45 yr) shows substantial changes in
the distribution of roosting shorebirds associated with habitat loss and shifts in foraging
areas (Battley & Brownell 2007). Declines in wrybill abundance over the past 30 years have
been associated with increasing abundance in Manukau Harbour, suggesting a gradual
redistribution of the population. Deposition of fine sediments associated with development
and land use practices in the catchment appear to have changed the composition of the
intertidal macrofauna and resulted in expansion of mangroves into areas formerly used by
wading birds. Key management issues are loss of intertidal foraging habitat for shorebirds
and open shore roosting areas (Battley & Brownell 2007).
Fig. 1. Boundaries of the Firth of Thames RAMSAR site (hatched area).
2.4 Sites of National Significance
Marine Reserves and by definition site of national significance (S. 3(1) Marine Reserves Act
1971). The existing marine reserves are:
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Cape Rodney-Okakari Point Marine Reserve (547 ha)
Tawharanui Marine Reserve (394.2 ha)
Long Bay-Okura Marine Reserve (980 ha)
Motu Manawa-Pollen Island Marine Reserve (500.78 ha)
10
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Te Matuku Marine Reserve (689.6 ha)
Whanganui A Hei Marine Reserve (840 ha)
Critical habitat for New Zealand fairy tern:
 Te Arai - a favourite post-breeding flocking site.
2.5 Threatened Habitats
Due to their limited spatial extent intertidal habitats and estuaries are threatened by
development and global climate change. Estuaries have been particularly heavily impacted
as they are the receiving environment for any activities occurring in the adjoining terrestrial
catchment and they are frequently subject to development focussed around ports and
subsequent urbanisation. Estuaries provide critical shore bird habitats, foraging and nursery
habitats for a number of commercially important coastal fishes, they are a critical migratory
corridor for most species of indigenous freshwater fishes and they support important
customary fisheries for shellfishes and fin fish. Pressures on estuaries include accelerated
infilling and elevated suspended sediment levels (increased turbidity) derived from increased
inputs of sediments, increased freshwater and nutrient inputs, chemical and microbiological
contaminanation, lose of marginal wetlands and coastal vegetation and alteration of
hydrological regimes due to reclamations, impoundments and causeway construction,
capital dredging, overfishing and introductions of nonindigenous marine species.
Subtidal seagrass beds within Hauraki Gulf Marine Park are confined to Whangapoa
Harbour, Home Bay, Mercury Island and Slipper Island (Schwartz et al. 2006; Matheson et
al. 2009). Historical records indicate these habitats have been lost from Waitemata Harbour
and possibly Tamaki Strait (Dromgoole & Foster 1983; State of the Gulf 2014).
Sensitive subtidal biogenic habitats are believed to have been extensively impacted and
modified by mobile fishing gears and sedimentation (Thrush et al. 1998).
3 Threats to Biodiversity
3.1 Key issues identified in the State of Our Gulf
Report 2014
The 2011 Hauraki Gulf State of the Environment Report (State of Our Gulf Report)
concluded that further loss of biodiversity and ecosystem services (natural assets) would
occur unless bold, sustained, and innovative steps were taken to halt progressive
environmental degradation. The overall conclusion of the 2014 State of Our Gulf Report is
that while some environmental improvements have occurred since 2011 the cumulative
impact of all activities is still driving progressive environmental decline. Indirect impacts of
catchment development on estuarine and inshore ecosystems are major contributors to this
decline. Run-off from urban and rural catchments contains a wide variety of contaminants
including sediments, nutrients, toxins, bacteria and viruses. Elevated freshwater inputs to
estuaries and enclosed coastal waters can also be considered a contaminant.
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The 2014 State of Our Gulf Report identifies the following issues of relevance to the
maintenance or restoration of marine biodiversity within the Hauraki Gulf Marine Park
(http://www.aucklandcouncil.govt.nz/EN/environmentwaste/naturalenvironment/Pages/stateo
fthehaurakigulf.aspx):
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Failure to consider the effects of fishing on marine ecosystems and dependent
species, particularly the direct impacts of trawling and dredging on the structure of
composition of benthic assemblages, and the indirect effects of the removal of
species known to mediate the structure and productivity of these assemblages. Rock
lobsters, an important predator on rocky reefs and sediment flats surrounding reef
systems, are considered to be functionally extinct throughout much of the Marine
Park.

Sediment is a serious environmental contaminant particularly in estuaries and
nearshore areas of the inner Hauraki Gulf. Adverse impacts of elevated sediment
levels in marine ecosystems are diverse and include: accelerated in-filling (aging) of
estuaries with associated increased discharge of sediments to the inshore
environment; smothering of benthic (bottom-living) organisms and settlement
surfaces for larval invertebrates; death of planktonic eggs and larvae; changes in
sediment composition resulting in long-term changes in benthic community
composition and function; reduction in the amount of light available to benthic plants
for photosynthesis; reduced foraging efficiency of visual predators such as juvenile
fishes; reduced feeding efficiency of filter-feeders; and avoidance of areas with high
concentrations of suspended sediments by some species. Increasing trends in the
proportion of fine and/or muddy sediments have been detected at sites in
Mangemangeroa, Okura, Puhoi, Turanga and Waiwera estuaries, Shoal Bay
(Waitemata Harbour), Mahurangi Harbour, and at some sites in the southern Firth of
Thames. Fourteen of the 19 water quality sites monitored by Auckland Council from
2004 to 2013 display deteriorating trends in total suspended solids (TSS)
concentrations. Modelling suggests that discharges from the Hauraki Plains dominate
sediment loads entering the Gulf, and that their footprint extends across the Firth of
Thames into Tāmaki Strait.

The largest nutrient inputs to the Hauraki Gulf come from land uses associated with
dairy farming on the Hauraki Plains. Waihou River provides about 58% of the total
nitrogen load to the southern Firth of Thames, and nitrogen concentrations in the
river have been increasing over the past 20 years. A long-term investigation by NIWA
indicates high nutrient inputs are leading to declining oxygen levels and acidification
of coastal waters of the Firth of Thames. Coastal nutrient concentrations have
generally been declining in the Auckland Region but nuisance phytoplankton and
seaweed blooms occasionally occur in the upper reaches of some estuaries (e.g.
Upper Waitematā Harbour, Tāmaki Inlet).

Low level sediment quality guidelines are frequently exceeded for copper, lead
and/or zinc in estuaries in Auckland with a long history of urban development and the
in south-eastern Firth of Thames. Mercury concentrations also exceed guideline
values around Thames and at sites in upper Tamaki Inlet, Hobson Bay and
Henderson Creek. Localised contaminant hotspots are also associated with ports,
marinas, landfills and industrial activity. Lead and copper concentrations are
declining in some of the worst affected estuaries in Auckland. However, copper and
zinc concentrations are still increasing in others. Zinc concentrations are increasing
most rapidly in upper Tamaki Inlet. Insufficient data is available from the Waikato
Region to assess temporal trends in heavy metals.
12

As well as being unsightly and a hazard to powered vessels, plastic refuse can kill
marine species including seabirds, turtles and baleen whales through entanglement
and injestion. Large amounts of rubbish continue to enter the marine environment
around Auckland but volumes have been declining since 2008. Information on trends
in the amount of coastal rubbish is not available for other areas. The ingestion of
plastic pellets is known to be an issue overseas1, but its impact on aquatic life in New
Zealand has not been assessed.

Introduced marine species pose a serious threat to marine ecosystems throughout
the Hauraki Gulf Marine Park. At least six non-indigenous species with the potential
to cause serious harm to the marine environment have already become established
in the Hauraki Gulf, with five high-risk species arriving in the past 15 years. Four new
species have been reported since 2011, one of which is a high risk species capable
of causing serious problems. The Port of Auckland is a key entry point for invasive
species and the large amount of boating and other marine-based activities centred
on it serve as vectors for the rapid spread of exotic species throughout the Marine
Park and to other regions. Controlling the spread and growth of established marine
pests is extremely difficult and to date no successful programmes have been
implemented. Management is therefore focussed on preventing their arrival and early
detection. Little is known about the potential long-term impacts of non-native species
on the indigenous biodiversity of the Gulf.

Bryde’s whales are a nationally critical threatened species due to their small
estimated population size of less than 250 mature individuals, of which about 46 are
resident in the Gulf. Since 1989 there have been 44 recorded fatalities of Bryde’s
whales in the Hauraki Gulf. Ship strikes account for 85% of the identified causes of
whale deaths. Some deaths have also been attributed to entanglement in fishing or
aquaculture equipment. This level of incidental mortality is considered unsustainable.

Since 2011 the conversation status of three of the 27 seabird taxa known to breed in
the Hauraki Gulf has declined and the status of one has improved. There are serious
concerns about the long term survival of four seabird species. The New Zealand fairy
tern is at risk of extinction, with only 12 breeding pairs and 40 individuals estimated to
remain. The NZ storm petrel was rediscovered in 2003 after being thought to be
extinct for 108 years. Risk assessment of black petrel estimates an average 1440
individuals are killed each year in fisheries. The bulk of these fatalities occur outside
the Hauraki Gulf Marine Park. Modelling suggests the population is declining by
2.5% per year, although this result is very uncertain. Relatively large numbers of
flesh-footed shearwater are also caught by long lines, and this has contributed to the
New Zealand population declining from 50,000–100,000 pairs estimated in 1984 to
less than 12,000 pairs currently. Again most fishery mortality on this species is
thought to occur outside the Hauraki Gulf Marine Park.

The Hauraki Gulf, particularly the Firth of Thames RAMSAR site, is an internationally
significant area for shore birds. Populations of some species using the Gulf are
declining however both endemic and migratory species are likely to be affected by
pressures and changes in habitat quality outside as well as within the Hauraki Gulf.
The nationally vulnerable New Zealand dotterel population within the Marine Park is
increasing in response to intensive management. Unmanaged New Zealand dotterel
populations tend to be stable or declining.
1
http://www.tangaroablue.org/amdi/campaigns/59-pellet-alert-project/203-survey-of-plastic-resin-pellets-between-cape-leeuwinand-burns-beach-western-australia.html
13

Exotic diseases are a threat to the biodiversity of the region. The clearest example
was the pilchard mortality in 1995, probably associated with imported bait from
Western Australia. Disease agents are associated with imported or translocated bait,
deliberate or accidental release of aquatic animals and in biofouling organisms.
Disease affects the environment in three ways – direct mortality of susceptible
animals (and plants), starvation of animals that rely on the affected animas for food,
and disruption of the ecosystem (which may be permanent).
3.2 Global Climate Change
Global climate change represents a chronic, long-term disturbance to marine ecosystems.
Environmental changes associated with climate change include increased sea surface
temperatures, changes in the frequency and intensity of storms and climate phenomena
such as the Southern Oscillation (the El Nino-La Nina cycle), changes in ocean circulation
and ocean acidification. The latter is likely to adversely affect organisms with calcium
carbonate exoskeletons such as some types of phytoplankton, corals, bryozoans and shell
fishes, and as noted above will be exaggerated by acidification of coastal waters caused by
nutrient inputs from terrestrial run-off. Sea-level rise will also create challenges for the
conservation of coastal biodiversity through impacts on intertidal habitats and the
composition of coastal vegetation types (in responce to changes in immersion-emmersion
and salinity regimes).
Negative effects of global sea-level rise on marine biodiversity will be greatest in estuarine
and coastal ecosystems. The most obvious effect will be the loss of coastal lagoons and wet
lands, shore bird nesting, roosting and foraging areas, and intertidal habitats unless the
ecological effects of coastal inundation are anticipated and planned for. Currently much of
the advice around planning for sea-level rise is focussed on coastal infrastructure and
property damage. Increased coastal erosion may also result in increased amounts of
terrestrial sediment entering the coastal zone.
3.2.1 Sea-level rise predictions
The Ministry of Environment (MfE) provides the following advice on planning for sea-level
rise. For further information see: http://www.mfe.govt.nz/publications/climate/preparing-forcoastal-change-guide-for-local-govt/html/page1.html.
New Zealand tide records kept by the three main ports, Auckland, Wellington and Lyttelton,
show an average rise in relative mean sea level of 1.6 mm per year (0.16 metres per
century) over the 20th century. The 33-year record kept at Mt Maunganui (Moturiki) shows
that sea-level changes in the Bay of Plenty have been similar to those in Auckland.
‘Relative’ and ‘absolute’ sea-level rise
The sea-level records from which historical trends in sea-level rise have been inferred are
made relative to the land on which the tide gauges are mounted. The relative sea-level rise
for a particular region or location is of prime importance when considering the impacts of
climate change at the coast. For projections of future sea-level rise we need to know the
absolute sea-level rise for the New Zealand region. An absolute value includes the amount
the land has risen or lowered over the time period considered.
14
Estimates of regional vertical land movements in New Zealand suggest the land is rising at
around 0.5 mm per year. Adding this to the annual average relative sea-level rise of 1.6 mm
suggests the absolute sea-level rise for New Zealand is around 2.1 mm per year. This is at
the high end of the observed global average absolute sea-level rise of 1.7 ± 0.5 mm per year
over the 20th century.
Future global sea-level change
Warming of the atmosphere results in reductions in the extent of snow and ice cover, as well
as warming and expansion of the oceans. The long delay between atmospheric temperature
rise and warming of the oceans means that even if global emissions were stabilised today
there would be continued thermal expansion of the oceans and melting of ice sheets and
glaciers on land until well after 2100. It is expected that sea levels will be relatively
insensitive to changes in emissions until about 2050 because of our past emissions. Future
changes and trends in emissions become increasingly important in determining the extent of
sea-level rise to expect beyond 2050.
Sea-level rise estimates
The Intergovernmental Panel on Climate Change (IPCC) reported a model-based range of
projected sea-level rise of 0.18–0.59 metres by the mid-2090s relative to the average sea
level over 1980–1999 (IPCC 2007) (Figure 2). This estimate is based on projections from 17
different global climate models, for six different future emission scenarios. The scenarios
consider different combinations of socio-economic profiles, energy use, and transport
choices into the future. The model estimates (light-blue shading) assume that the
contributions from ice flow from Greenland and Antarctica remain at the rates observed for
1993–2003. These rates are expected to increase in the future, particularly if global
greenhouse gas emissions are not reduced. An extra 0.1–0.2 metres rise in the upper
ranges of the emission scenario projections (dark-blue shading) would be expected if these
ice sheet contributions were to grow in line with global temperature increases. An even
larger contribution from these ice sheets, especially from Greenland, cannot be ruled out in
the 21st century.
Future sea-level rise advice for New Zealand
The uncertainties associated with sea-level rise projections means a range of sea-level rise
values should be considered when assessing what the effects of sea-level rise may be. Any
decisions on the extent of sea-level rise to plan for, should consider:



the possibility and consequences of particular sea levels being reached within the
planning timeframe
the potential costs of adapting to a particular sea level rise
how any residual risks would be managed for consequences over and above a
particular sea-level rise threshold, or if sea-level rise is underestimated.
Planning for sea-level rise is best based on the IPCC Fourth Assessment Report sea-level
rise estimates. Consideration should also be given to the potential consequences from
higher sea levels resulting from factors not yet included in the current global climate models.
One uncertainty is how fast the Greenland and Antarctica ice sheets will melt. Another
uncertainty arises from possible differences in mean sea level when comparing the New
Zealand region with global averages.
MfE recommends that for planning and decision timeframes out to 2099:
15


a base value sea-level rise of 0.5 m relative to the 1980–1999 average be used,
along with
an assessment of potential consequences from a range of possible higher sea-level
rise values. At the very least, all assessments should consider the consequences of
a mean sea-level rise of at least 0.8 m relative to the 1980–1999 average.
For longer planning and decision timeframes beyond the end of this century an additional
allowance for sea-level rise of 10 mm per year beyond 2100 is recommended. Table 1
summarises the baseline sea-level rise recommendations for planning and decision
timeframes over the 21st century.
Fig. 2. Observations of past sea-level rise and projections of future global mean sea-level rise to the
mid-2090s.
16
Table 1. Baseline sea-level rise recommendations for different future timeframes, in metres relative to
the 1980–1999 average.
Timeframe
2030–2039
2040–2049
2050–2059
2060–2069
2070–2079
2080–2089
2090–2099
Beyond 2100
Base sea-level rise
allowance (m)
0.15
0.20
0.25
0.31
0.37
0.44
0.50
10 mm/year
Also consider the consequences of
sea-level rise of at least: (m)
0.20
0.27
0.36
0.45
0.55
0.66
0.80
4 Marine Protected Areas
Definition of Marine Protected Area
Marine Protected Area (MPA) is an umbrella term used to describe a wide range of areas
protected for marine conservation. The Convention on Biological Diversity (CBD) defines
marine and coastal protected areas as "an area within or adjacent to the marine
environment, together with its overlying waters and associated flora, fauna, and historical
and cultural features, which has been reserved by legislation or other effective means,
including custom, with the effect that its marine and/or coastal biodiversity enjoys a higher
level of protection than its surroundings".
The New Zealand Marine Protected Areas Policy and Implementation Plan (MPA Policy)
reflects the commitment by the Government through its ratification of the CBD and
development of the New Zealand Biodiversity Strategy (NZBS) to help stem the global loss
of biodiversity. The MPA Policy is intended to assist government achieve Objective 3.6 of
the NZBS which is to protect a full range of natural marine habitats and ecosystems to
effectively conserve marine biodiversity, using a range of appropriate mechanisms, including
legal protection. The MPA policy recognises that a range of management tools, including
marine reserves and Fisheries Act 1996 tools, can be used to protect marine biodiversity.
The MPA Policy Protection Standard provides an outcomes-based definition of an MPA. To
satisfy the protection standard a management tool must enable the maintenance or recovery
of a site’s biological diversity at the habitat and ecosystem level to a healthy functioning
state. In order to do this the management regime must provide for the maintenance and
recovery of:
a) Physical features and biogenic structures that support biodiversity;
b) Ecological systems, natural species composition (including all life-history stages),
and trophic linkages; and
c) Potential for the biodiversity to adapt and recover in response to perturbation.
Management tools recognised as meeting these requirements are marine reserves
established under the Marine Reserves Act 1971 (Type I MPAs) and Fisheries Act 1996
prohibitions on dredging, trawling, Danish seining, purse seining, gillnetting and potting
(when on sensitive biogenic habitats) (Type II MPAs). Other tools that may meet the
requirements of a Type II MPA include cable protection zones, marine mammal sanctuaries,
17
Resource Management Act, possibly in combination with tools available under other acts
(pp. 12-13, Marine Protected Areas Classification, Protection Standard and Implementation
Guidelines 2008).
The 2012 International Union for the Conservation of Nature (IUCN) definition of an MPA is
“a clearly defined geographical space, recognised, dedicated and managed, through legal or
other effective means, to achieve the long-term conservation of nature with associated
ecosystem services and cultural values”.
In general the purpose of all MPAs is the conservation of biodiversity, or in some cases
cultural heritage, and they are distinguished by a higher level of protection than surrounding
areas.
Differences between the Marine Reserve Act 1971 and Fisheries Act 1996 tools
The most important difference between marine reserves established under the Marine
Reserves Act 1971 and Fisheries Act 1996 tools is that marine reserves are able to protect
the habitat from disturbances unrelated to fishing such as discharges, dumping, mining and
structures. Fisheries Act tools can offer more flexibility to a variety of fishery uses that may
be compatible with varying degrees of marine protection.
Existing Marine Protection within the Hauraki Gulf Marine Park
There are six marine reserves (Type I MPAs) within the Marine Park, they are: Cape
Rodney-Okakari Point Marine Reserve (529.8 ha), Tawharanui Marine Reserve (394.2 ha),
Long Bay-Okura Marine Reserve (962.7 ha), Motu Manawa-Pollen Island Marine Reserve
(500.5 ha), Te Matuku Marine Reserve (687 ha) and Te Whanganui-A-Hei (Cathedral Cove)
Marine Reserve (886.7 ha). Collectively they cover 0.28% of the total area of the Marine
Park. In addition there are three cable protection zones that are reognised as Type II MPAs.
The largest of these is the Hauraki Gulf Submarine Cable Closure (HGSCC) which covers a
total area of 74341.9 ha. At its narrowest point off Takapuna the HGSCC is 1.6 km across.
At its widest in the outer Gulf it is over 10 km across. The combined coverage of Type II
MPAs is 5.46% of the Marine Park, of which 96.72% is the HGSCC. The biological
assemblages in all of the marine reserves have been documented in some way, either in the
original application or in monitoring programmes and research projects. In contrast, very little
is known of the biology of any of the Type II MPAs.
The total area covered by existing MPAs is 80,826.607 ha, or 5.74% of the Marine Park.
Jackson (2014) developed a habitat classification based upon substrate information
developed for the Hauraki Gulf Marine Spatial Plan and the New Zealand Coastal
Classification (MPA Policy Guidelines 2008) and used this to assess the representativeness
of the existing MPA network in the Marine Park. This classification identified 46 coastal and
marine habitat types within the Marine Park, of which only two (sheltered coarse and mixed
sediments below 30 m depth) have 10% or more of their extent protected within Type I or
Type II MPAs. In both cases this is attributable to the amount of these habitats occurring
within the HGSCC. Half of the identified habitats are not protected within any MPA (Jackson
2014). The most extensive habitats within the Marine Park are muddy and sandy mud
substrata occurring between 30-200 m depth. Currently very few habitats occurring deeper
than 30 m are protected within no-take marine reserves as only a small proportion of marine
reserves exceed 30 m maximum depth (Jackson 2014).
18
MPA network design principles
New Zealand’s marine reserves were established individually and independently to protect
local-scale marine wildlife, rather than systematically as a coherent network designed to
protect national-scale biodiversity and ecosystem services (Thomas & Shears 2013). The
New Zealand Marine Protected Areas Policy and Implemenation Plan (MPA Policy) and the
Marine Protected Areas Classification, Protection Standard and Implementation Guidelines
(MPA Policy Guidelines) were developed to address the NZBDS objectives, particularly the
development of network of MPAs that is comprehensive and representative of New
Zealand’s marine habitats and ecosystems (pg. 10, para. 13). In this context comprehensive
means capturing as much as possible of the full range of biodiversity present within New
Zealand’s marine environment, and representative means containing a representative
selection of habitats and ecosystems.
There is a large scientific literature on the design of MPA networks, much of it relating to the
use of MPAs as fishery management tools (e.g. Martell et al. 2000; Bentley et al. 2004;
Pelletier & Mahévas 2005; White et al. 2010). However, using spatial tools to manage or
eliminate human activities that adversely affect the marine environment is also an effective
way of contributing to the long-term ecological viability of marine ecosystems (Marine Parks
Authority 2008). Guidance on ecological principles for the design of MPAs and MPA
networks is contained in the MPA Policy (2005) and MPA Policy Guidleines (2008), and
reviews such as IUCN (2008), Gaines et al. (2010), Fernandes et al. (2012) and Thomas &
Shears (2013). Design principles emphasized in these documents are:
1. Inclusion of the full range of biodiversity present in a biogeographic region through
 representation of all habitats and ecosystems
 replication of protection for each habitat and/or ecosystem within the network
 protection of habitats that exhibit resilience or resistance to long-term environmental
stressors (e.g. sedimentation, raised temperatures)
2. Ensure ecologically significant areas are incorporated by
 protecting unique or vulnerable habitats (e.g. biogenic habitats)
 protecting critical habitats such as foraging or breeding grounds
 protecting source populations, i.e. those that export larvae, juveniles and adults to
other areas
3. Maximise the contribution of individual MPAs to the network through careful
consideration of their:
 size - in general larger MPAs will protect a greater variety of habitats and
biodiversity, as well as providing a buffer against edge effects of fishing; some
studies recommend large numbers of smaller MPAs for fisheries management
objectives; although physically capable of swimming long distances many reef fishes
are home ranging or territorial (e.g. McCormick 1989; Cole et al. 2000; Parsons et
al. 2010); home ranging behaviour is a characteristic that increases persistence of
species within MPA networks (Moffitt et al. 2009)
 spacing – optimal spacing will vary depending on the objectives of MPA
management and the species involved; while many marine species have long-lived
pelagic larvae capable of dispersing hundreds to thousands of kilometers, many
seaweeds and benthic (bottom-living) invertebrates produce large, negatively
buoyant, short-lived larvae that may stay in the plankton for less than an hour to just
a few days, other species brood their young; dispersal distances of the latter vary
from a few metres to a few kilometers
19

shape – boundaries should reflect natural ecological boundaries and be simple (to
facilitate compliance and enforcement); the design of individual reserves should aim
to minimize the area to boundary length ratio in order to minimize edge effects
4. Consider hydrographic and ecological linkages between the land and sea – it is
particularly important to consider potential land-based impacts on the marine
environment when thinking about establishing MPAs in enclosed coastal waters or
estuaries, MPAs are unable to directly influence activities occurring in adjoining
catchments
5. Minimise adverse economic and social impacts on existing users
Proportion of an area to include in an MPA network
The Convention of Biological Diversity (CBD) and New Zealand Biodiversity Strategy
establish a target of 10% of the marine environment protected within MPAs. However more
recent research predicts that maximum benefits for biodiversity conservation and fisheries
are likely to occur between 30-50% coverage by MPAs. In most cases extension of MPA
coverage to more than 50% coverage of a fishery is predicted to adversely impact fishery
yields due to the displacement of fishing effort into the remaining unprotected areas (Gaines
et al. 2010). In this context it is important to note that geographic coverage of a specific area
such as the Hauraki Gulf Marine Park is unlikey to equate to the spatial coverage of a
fishery. For example rocky reefs represent only a relatively small proportion of the total area
of the marine park. As a result the spatial extent of fisheries for reef species such as kina
and rock lobster will be much smaller than the area of the park, and usually much less than
the total area of reef due to the habitat requirements of the species involved.
Using conservation planning software or spatially explicit fishery models allows objective
assessment of the cost-benefit of trade-offs between conservation goals and exploitation of
marine resources (e.g. Bentley et al. 2004; Pelletier & Mahévas 2005; Leathwick et al.
2008). Leathwick et al. (2008) demonstrated the use of conservation planning software
(Zonation) to design MPA networks in New Zealand’s Exclusive Economic Zone. Using
predicted distributions of 96 demersal fishes sampled by research trawls and information on
the location of commercial bottom trawling they demonstrated that protecting 10% of the
habitat based solely on estimated conservation value, without regard for the impact on
fishing, would on average protect 27.4% of the geographic range of each fish species and
reduce fishing opportunity by 22%. Using the algorithm to select high conservation value
sites but avoiding important fishing areas, produced a solution that on average protected
23.4% of the range of each species (marginally lower than the solution that ignored fishing
effort) but had no impact on fishing. Increasing the level of spatial protection to 20% but still
avoiding heavily fished areas produced a solution that would increase average species
protection by 50% with minimal cost to the fishing industry (Leathwick et al. 2008, fig. 5).
This solution had greater predicted conservation benefits and less impact on fishing
opportunity than the Benthic Protected Areas which were developed using expert opinion
and a physical classification of the marine environment (Helson et al. 2010; Reiser et al.
2013).
5 Biosecurity threats to the Hauraki Gulf
Because of New Zealand’s geographic isolation, more than 95% of our trade is reliant on
ocean borne transport. This predisposes us to marine biosecurity risks, namely the
introduction of non-indigenous organisms (or hitchhikers) into our marine environment. Our
20
fisheries (> $1.5 billion per year), aquaculture (>$300 million per year) and recreational,
cultural and amenity values all have the potential to be threatened by marine pests.
Risk pathways for marine organisms entering New Zealand include biofouling, ballast water,
solid ballast, aquarium or ornamental fish trade, aquaculture feed and stock and bait fish.
By far the biggest risk comes from fouling with non-indigenous organisms hitchhiking on the
dirty bottoms and niche areas (such as sea chests) of international ocean-going vessels.
In spite of efforts to reduce risks offshore and at the border, there have been a number of
marine pest incursions in recent years which have led to pests becoming established in parts
of New Zealand. Established marine pests such as Styela clava and Mediterranean fanworm
are continuing to spread throughout the country, often resulting in technically difficult and
costly regional response operations. Costs for a small regional marine response can typically
be in the $20 - $50k range; at the other end of the range, costs for the eradication response
to Undaria in Sunday Cove, Fiordland are in excess of $600k.
The capability to undertake national marine surveillance and responses has been in place
for several years, however management of the pathways of spread is a relatively new tool
for marine biosecurity.
The Pest Management National Plan of Action recognised that prevention of spread is more
cost effective than responding to range extensions of established marine pests, and that
pathways management needs to be an integral part of New Zealand’s marine biosecurity
system. The Plan of Action therefore proposed that future marine pest management action
should focus on preventing the spread of established pests, and noted that effective
management requires cooperation and partnerships (e.g. between MPI, councils, tāngata
whenua and industry).
Domestic pathways management has multiple benefits – it can reduce the spread of new to
New Zealand pests prior to detection (meaning smaller and more effective incursion
responses), and prevent established pests moving between regions or to high value places
within a region. An example of a domestic pathway includes the activity of dredging and
dumping of marine spoil.
As of 2013 a total 162 non-indigenous marine species were considered to have established
in New Zealand waters. In addition, 118 species are suspected to have originated from
overseas and 154 non-indigenous species have been recorded from New Zealand waters
but have not established self-sustaining populations. A further 235 recently described
species have uncertain origins (cryptogenic species) (G. Inglis, NIWA, presentation to
Biodiversity & Biosecurity Roundtable).
The Port of Auckland represents a major point of entry for non-idigenous marine species into
New Zealand’s coastal waters, and into Hauraki Gulf from other parts of New Zealand via
ballast water and hull fouling. The port is a major hub for the marine transport industry and
recreational vessels. Once established in Auckland non-indigenous species are rapidly
transported throughout the Gulf and the rest of New Zealand. The Craft Risk Management
Standard (administered by MPI) comes into place in May 2018, and will apply to reduce the
risks associated with biofouling organisms from vessels recently arrived from other
countries.
Research on the ecological impacts of non-indigenous species is limited. Mats of Asian date
mussel reduce species richness and abundance of invertebrates in underlying sediments but
these impacts appear to be localised and transient (Creese et al. 1997). The presence of
established populations of non-indigenous benthic species does not appear to make
21
establishment easier for other non-indigenous species, whereas the presence of healthy,
undisturbed populations of the indigenous burrowing urchin Echinocardium cordatum has
been found to reduce the ability of non-idigenous benthic species to establish in an area
(Lohrer et al. 2008 a,b,c). However the Asian lady crab has been found to preferentially feed
on burrowing urchins, bivalves and native crabs (Townsend et al. 2014). No research has
been done on the ecological impacts of the Pacific oyster.
Eradication and control of non-indigenous marine species once they have established is
extremely difficult, however effective means of preventing these species entering New
Zealand waters are also lacking or in the developmental stages. MPI has recently released
the Craft Risk Management Standard (CRMS) on biofouling on vessels arriving in New
Zealand. The CRMS has a 4 year lead-in period and will become mandatory in 2018. New
Zealand’s economy depends heavily upon the martime transport industry but is itself only a
relatively small market and therefore has limited ability to influence international shipping
practices through economic or legislative tools. Control of nonindigenous marine species
can be addressed through national and regional pest and pathway strategies and
management plans2.
Non-indigenous marine species established in the Gulf include the Pacific oyster
(Crassostrea gigas), Asian date mussel (Musculista senhousia), the small semelid bivalve
Theora lubrica, the Australian oyster blenny (Omobranchus anolius) and bridled goby
(Arenigobius bifrenatus), Asian paddle crab/Asian lady crab (Charybdis japonica), the Asian
seaweed Undaria pinnatifida, the green seaweed Codium fragile tomentosoides and the
Mediterranean fan worm (Sabella spallanzanii) (http://www.marinebiosecurity.org.nz/).
Genetic analysis of populations of blue mussels in Hauraki Gulf also indicates the presence
of both indigenous Southern Hemisphere and non-indigenous Northern Hemisphere
lineages of Mytilus galloprovincialis (Gardner & Westfall 2011).
6 References
Baker, C. S.; Chilvers, B. L.; Constantine, R.; DuFresne, S.; Mattlin, R. H.; van Helden, A.;
Hitchmough, R. 2010. Conservation status of New Zealand marine mammals
(suborders Cetacea and Pinnipedia), 2009. New Zealand Journal of Marine and
Freshwater Research, 44: 101-115.
Battley, P. F.; Brownell, B. (ed.) 2007. Population biology and foraging ecology of waders in
the Firth of Thames - update 2007. Auckland Regional Council, Technical Publication
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