Reel Life March 2023

Drift dive confirms most Waikato fish survived the storm

Although large floods don’t often kill fish, catastrophic 100-year events can wipe out lowland fisheries.

Staff have been able to squeeze in some late drift dives in the upper Waihou, Mangatutu and Awakino.

The results have been promising, considering the horrible weather we have had this summer.

All of our rivers are far colder than normal with many rivers sitting at 12-14°C when we would expect them to be upwards of 18°C.

This is great for fish growth but not for getting a representative fish count.

Most of our drift dive locations are in the upper catchment where water clarity is good prior to being degraded by agricultural inputs.

Staff normally conduct drift dives when air and water temperatures are high forcing most of the fish into our monitored river reaches.

Due to the cold water this year, fish could be spread out throughout the river system likely reducing the number of fish we count.

The Mangatutu water temperature was below 13°C, so fish that would have normally been pushed up from the lower river and the Puniu were likely spread out over a much larger area.

As a result, we counted less fish than normal, but the river was not physically impacted by the floods, and there were ample small fish.

Similarly, the Awakino was also unseasonably cold with fewer large fish and more small fish than normal.

We have produced a video of the Awakino drift dive if you would like to check it out.

Above Right: Viktoriia Levchenko after seeing a large Awakino rainbow.

Fishing report

The muddy Mangatutu track.

Fishing reports have been good to moderate likely due to the cold water spreading fish out similar to what you would expect in late May.

There are plenty of fish around; the biggest difference we have seen in our drift dives has been habitat use.

Staff count most of the fish in our rivers in deep pools in the summer with some pools on the Whakapapa holding 20 fish.

During the colder drift dives we have conducted post-cyclone, we have seen a lot less fish in pools and more in runs and bolder gardens.

So, if you are into Euro nymphing, the shift in habitat use should suit you well.

Staff hope to drift dive the Waitawheta next week as there were reports of extreme flooding and low fish numbers post-cyclone.

Tight Lines

Adam Daniel, Auckland Waikato Fish & Game