Connectivity: fish migration

1
Connectivity fish migration passage

• Native fish
• most migratory species close to coast
• most that penetrate far inland are good climbers
  (e.g. longfin eels, koaro)
• fish pass requirements are low tech
• dam height is an issue
• downstream passage of eels what out for
  turbines
• Salmon and trout
• fish passes not good track record in NZ
• has potential but Fish Game will need
  convincing overseas working examples
• dam height is an issue

2
Flow augmentation positives negatives

• Positives
• harvest of high flows
• enhance minimum flow for instream values

• Negatives
• fish passage loss of headwater habitat
• may reduce median flow productive capacity
• periphyton proliferation through flow
  stabilisation

3
Dams/reservoirs negatives vs positives

• Negatives
• barriers to migration
• extirpation of stocks dependent on feeding
  habitat downstream (e.g. large trout)
• loss of upstream habitat (e.g. koaro threatened
  longin eels)
• loss of river angling amenity
• inundation of habitat of wetland native fish
  (e.g. mudfish)
• inundation of natural barriers protecting
  non-migratory galaxiids from trout

• Positives
• creation of reservoir recreational amenities
• angling
• boating amenities
• swimming