Whitebait hatching experiment with Environment Canterbury

Our discovery of whitebait spawning sites in Kaikōura streams (see Recover Issue 3) ended with a twist in Waikoau / Lyell Creek when we realised that the eggs were unlikely to hatch. Thanks to Pete Adams at Environment Canterbury we came up with an engineering experiment in the form of a temporary closure — the reverse of mechanical stream openings that are routinely used to alleviate flood waters backing up after natural river mouth closures. In this case we temporarily blocked the mouth with gravel to raise the water level around 40 cm for just a few hours. That was enough to hatch out our īnanga/whitebait eggs that had been found four weeks previously, high on the river bank. This very simple experiment would not be feasible in most rivers but did demonstrate a successful rescue plan to give some stranded fish eggs a much needed helping hand!

Read more on the Environment Canterbury site here

Shane and Pete at the mouth of Waikoua / Lyell Creek after pushing up a small gravel bund to raise the water level for a few hours. Picture by Thomas Falconer.

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