the same area as the favourable run/riffle habitat for koaro and juvenile longfin eel, discussed
earlier. This area was estimated to occur at a maximum of 20% of the riverbed area, equating
to 460m of riverbed. Given that invertebrate densities were low from within these areas, an
estimated 20-30% of territory for one blue duck breeding pair is potentially represented within
the 2.3 km gorge section. The rugged nature of the gorge may however make predator access
more difficult than normal, and hence appealing as a possible nesting area, as predation is
probably the key determinant of present day remnant blue-duck distribution within Kahurangi
National Park.

If the 200-500 metres of potentially affected feeding area below the gorge outlet is added to
this estimate, then habitat capable of potentially providing around 50% of the territory for a
breeding blue duck pair may be affected.

The upper Parapara River, above the proposed intake site, provides a much higher density of
invertebrates and hence potential blue duck feeding area, than habitat within the gorge itself.
The upper Parapara was surveyed over the 1999/2000 summer as part of a wider blue duck
survey (Studholme 2000). No blue duck or blue duck sign was noted during the survey at that
time


Conclusions

•  Although a relatively unproductive system, Parapara River has moderate numbers of a
  reasonably diverse range of native migratory galaxiids, particularly within the 500
  metre intermediate gradient river section immediately below the gorge outlet, near
  where the powerhouse discharge point is proposed. The density of shortjaw located
  below the gorge outlet appeared low-moderate.
  
•  Between 200-500 metres of intermediate gradient stream habitat for a low-moderate
  density of shortjaw kokopu could be affected by altered flow regimes of the scheme,
  depending upon the location of the powerhouse. The closer to the gorge the
  powerhouse discharge is located, the less shortjaw habitat will be affected.
  
•  The section of Parapara River within the gorge provides limited longfin eel and koaro
  habitat, due to the high gradient and limited invertebrate productivity. However it is
  an important migratory route for these and potentially one or two other galaxiid
  species to access the lower gradient sections of the river above the gorge.
  
•  Estimates of fish habitat loss through Instream Flow Incremental Methodology (IFIM)
  would be difficult to achieve within the gorge as the basic assumption underlying such
  are technique are violated due to the high gradient nature of the riverbed.

Fish & Game New Zealand Nelson Marlborough Region Sports Fish and Game Bird Management ...p24