​Īnanga spawning resources

The doc is about inanga, a native whitebait species in NZ. It covers their life cycle, spawning needs, threats like habitat damage and barriers, and ways we can help protect and restore their river habitats to support their survival.

The National Inanga Spawning Education Programme teaches about Īnanga, their life cycle, spawning needs, threats to their survival, and how we can protect their habitats to help their numbers recover.

Adult inanga are small fish that swim in shoals near river mouths. Females are slightly larger and show visible eggs when spawning. Their tiny, clear eggs are 0.8–1.2 mm, while similar-looking slug eggs are larger, milky white, and can be mistaken for them.

To find inanga spawning sites, search 2–3 days after spring tides from Jan to June, especially in April. Look near the upstream limit of saltwater in rivers at low tide. Use tide charts and moon phase calendars to plan the best time to check riverbanks.

This activity sheet explains how to find the saltwater wedge in rivers using a salinity meter during spring tides. It helps identify where inanga are likely to spawn by tracking where saltwater reaches, and provides tips, data collection methods, and key things to watch for.

This activity sheet explains how to assess inanga spawning habitat using a 12-point checklist. It compares historical and modern vegetation and helps you score a site's condition. Good habitats support high egg survival, while poor ones risk total egg loss.

The guide helps assess and protect inanga spawning sites by scoring habitat quality, checking fish and saltwater access, vegetation, and bank conditions. It also explains how to count eggs and monitor spawning to support conservation and restoration efforts for whitebait habitats.

Straw/hay bales can be installed near the highwater mark to create temporary inanga spawning habitat. Bales are placed in pairs, secured with stakes and wire, and offer shade, moisture, and protection—mimicking natural vegetation.

Maintaining inanga spawning sites means protecting the right conditions—vegetation, tides, saltwater mix, and timing. Livestock harm sites by grazing plants and damaging soil. Fencing and careful management are key to keeping these habitats healthy.

Long-term inanga habitat restoration means fixing issues like fish/saltwater access, bank slope, poor soil, or vegetation. Solutions include regrading banks, changing plant maintenance, fencing out livestock, and removing pest plants to boost egg survival.

Inanga need specific conditions to spawn. Disrupting any—like tide timing, salt/freshwater mix, or vegetation—can stop spawning. Livestock damage banks and vegetation, harming egg survival. Protecting sites is key to supporting whitebait life cycles.

Straw bales help restore inanga spawning by mimicking natural habitat during high spring tides. They protect eggs and show ideal spawning zones for long-term restoration. Please don’t disturb the bales—report damage to info@whitebaitconnection.co.nz

15 key plant species—like flax, toetoe, wīwī, and cabbage trees—are used to restore inanga spawning habitat. Prep includes weed control, fencing, and timing to avoid egg damage. Native plants improve moisture, shade, and egg protection.