Whitebait spawning sites in Kaikōura’s rivers

Early in 2019 we started work to fill a knowledge gap about whitebait in streams and rivers along the Kaikōura coast. For īnanga, which makes up the bulk of the whitebait catch, the spawning grounds are usually found close to the coast near the river mouths. Knowing where they are is useful for recovery planning in the same areas post-earthquake as well as for restoration projects in local waterways. Our survey programme started with fish trapping to find out which species were living in which rivers, after which we selected waterways that were suspected to have good īnanga populations. They included seven catchments close to Kaikōura (Oaro, Kahutara, Lyell / Waikōau, Middle, Swan, Harnetts and Blue Duck) as well as other sites in Marlborough. After four months of surveying we discovered at least one spawning event in all of these streams and rivers and were able to map the spawning locations including some large sites!

Spawning events often coincided with a rise in water levels due to rain events leaving the eggs high above the normal waterline where they can be easily disturbed. The spawning grounds themselves were not always in the same locations but we now have a better understanding of where they might be to make sure they are protected. We also followed the fate of some sites through to hatching… stay tuned for more on this in the next issue of Recover.

Thomas Falconer surveyed in Lyell Creek where we found several spawning sites in down-town Kaikōura! (bottom). The fish have very likely benefitted from the restoration efforts underway in the Waikōau catchment that have improved the riparian habitat. Picture by Shane Orchard.

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