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Marlborough Sounds
Map ID number:
9
Location: Cloudy Bay to
Croiselles Harbour, Tasman
Bay
Approximate area: 4,450km 2
Description of area:
The Marlborough Sounds are a complex
drowned valley system spanning strong gradients
in depth, tidal mixture, temperature, and
wave exposure. As a result of these physical
influences there are a wide range of habitats,
including stream mouths and large estuaries,
sheltered rocky shores with low algal biomass,
shallow sand and mud habitats, and exposed
eastern shores subject to high wave exposure
and strong tidal currents.
Biological attributes:
Small pelagic fishes, such as sprats (Sprattus
spp.), anchovy (Engraulis australis),
and pilchards (Sardinops neopilchardus) are
abundant in the Marlborough Sounds. These
are important prey for seabirds such as shearwaters
and gannets, and for bottlenose, dusky,
and Hector’s dolphins. Estuaries and streams
in the area are important for diadromous fishes
(fishes that migrate between fresh and salt
waters). Bryozoan beds at Chetwode, Titi,
Trio, and Rangitoto islands support diverse
assemblages of small benthic fishes (including
juvenile commercial species such as blue
cod (Parapercis colias). Large schools of
planktivores (predominantly butterfly perch
Caesioperca lepidoptera) also live among
the bryozoan beds. Deepwater emergence is
observed at Port Underwood where lantern
fishes, rat tails, and dark ghost sharks (Hydrolagus
novaezealandiae) are found shallower
than in other regions. The inner Queen
Charlotte and Pelorus Sounds are spawning
grounds for elephant fish (Callorhinchus
milii). The Marlborough Sounds are the
southern range limit for pink brotula (Brosmodorsalis
persicinus): Queen Charlotte Sound
and Port Hardy are the only sites south of East
Cape where this species has been recorded.
Criteria for inclusion:
Dependency for other species; trophic/functional
diversity; representation (i.e. across
physical types); extremities of range and
adaptation to environment; degree of disturbance;
special conditions and specialised
organisms; habitat complexity/diversity.
Status and management:
The Marlborough Sounds are major recreational
fishing grounds, particularly for blue
cod. However, rocky habitat is limited to a
thin strip around the sides of most sounds,
which means that overfishing is a problem.
Allowable catches for both commercial and
recreational fisheries have been reduced in
response. In the outer sounds and Cook Strait
there is an important commercial and recreational
hapuku (Polyprion oxygeneios) fishery.
There were historical fisheries for this species
inside both sounds.
State of information:
Moderately well studied.
References and further reading:
C. Duffy (unpubl. data), Hurst et al. (2000b),
Johnston (1983).
Pegasus Bay/
Canterbury Bight
Map ID number:
10
Location: Waitaki River to north
of Waimakariri River
Approximate area: 22,288km 2
Description of area:
Long, exposed, soft-shore coastline with a
major rocky headland, Banks Peninsula. There
is high primary productivity at times in the
Canterbury Bight.
Biological attributes:
Stokell’s smelt (Stokellia anisodon) is
endemic to the eastern South Island. It is the
only diadromous freshwater fish species that
does not have a New Zealand-wide range. The
reasons for this restricted range are not understood,
but may relate to enclosure of a triangular
area of sea inside the current system that
passes north from Otago and along the Canterbury
coast. Interestingly, this is the same
area inhabited by the introduced Chinook
salmon (Oncorhynchus tshawytscha) population,
which undergoes natural dispersion in the
sea. Other notable species found in this area
include basking shark (Cetorhinus maximus),
elephantfish (Callorhinchus milii), and red
cod (Pseudophycis bachus). Basking sharks
are common in spring and summer from the
edge of the shelf to the coast, and even in Lake
Ellesmere. During this period elephantfish
form spawning aggregations and lay their eggs
in shallow water. Red cod also form large
aggregations in some years.
Criteria for inclusion:
Species richness; endemism; dependency for
other species; trophic/functional diversity;
representation (i.e. across physical types);
degree of disturbance; seasonal/migratory
importance; unusual degree/proportion of
biomass; aggregations; habitat complexity/
diversity; meeting ground – overlap between
biological regions (at national and global
regions level.
Status and management:
There are major fisheries along this coast, and
some estuaries and bays are heavily impacted
by human shore-based activities.
State of information:
The fish fauna has been intensively studied,
especially on the continental shelf and upper
continental slope.
References and further reading:
Beentjes and Renwick (2001), Beentjes
et al. (2002), Francis (1997), Francis and
Duffy (2002), Gorman (1963), McDowall
(1990).
BIODIVERSITY – NEW ZEALAND’S MARINE ECOREGION ■ 39