‘Love zones’ are helping threatened īnanga recover from Cyclone Gabrielle, with delighted DOC rangers finding clutches of īnanga eggs in these artificial spawning grounds.
DOC ranger Matt Brady says spawning is an essential part of the īnanga life cycle, but having exactly the right environment can be tricky, and in the Hawke’s Bay, some of that habitat was washed out by the cyclone or choked with silt.
“We know īnanga are threatened and that good spawning habitat is crucial for them to survive and thrive. Īnanga are also part of the whitebait catch, so if we want a sustainable whitebait fishery, we need to look after them.”
For the spawning season earlier this year, Matt and his team laid mats made of coconut to act as artificial spawning habitats around river mouths throughout Hawke’s Bay. While hay bales are a more traditional artificial spawning habitat, Matt says the coconut mats are much easier to lug from the truck to the river than hay bales.
DOC staff half-jokingly call the stretches of Hawke’s Bay rivers with artificial spawning mats ‘love zones’, but Matt says it’s actually an apt description.
“Baby īnanga are made when eggs and milt (sperm) are released in autumn, and the eggs are fertilised in vegetation beside rivers and streams. The conditions need to be just right for this to happen, but unfortunately the cyclone severely compromised many spawning habitats in the Hawke’s Bay.
“Artificial spawning habitats in ‘love zones’ help us identify spawning sites, and give īnanga a boost. We gave this a bit of a trial run last year and got good results, with some eggs.”
This year, DOC has extended the love zones, working with Hawke’s Bay Regional Council, Ngāti Pāhauwera, and Waimārama hapū members.
“Imagine my delight when I saw clutches of eggs while monitoring Waikare River this autumn. The abundance of eggs in the artificial habitats really showed their effectiveness.”
In early winter, the eggs hatch into larvae and float downstream, spending the colder months at sea fattening up before returning to freshwater in spring as juveniles.
Matt says love zones aren’t only about making īnanga babies, although that’s very important.
“Love zones are also a way for us to research and monitor īnanga populations and find out more about īnanga behaviour, and identify habitats for protection.”
Members of the public can also do their part to help īnanga. Naturing for īnanga can include joining a local stream care group, fencing streams from stock, and reporting barriers to fish movement.
Learn more about īnanga on the DOC website.
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