Reel Life March 2025 - Auckland Waikato

Please help us by reporting tagged fish

Staff have been amazed with the number fish counted during the 2025 drift dives. Three of the five rivers surveyed had extremely high fish counts due to high water temperatures and low flows. A new reach of the Whakapapa was surveyed in March that had one of highest densities of large rainbows ever recorded in the river. We highly recommend getting out for fish during the tail end of the summer as seasons like this are not to be missed.

With fish so concentrated we expect some tagged fish to be caught on the Whanganui, Whakapapa and the Mangatutu during the next month. If you do get out for a fish, please be ready to record fish tag numbers (you can take a picture) and the fish length (from the nose to the fork in the tail). Accuracy is important as fish are measured to the millimetre, so if you don’t have a tape measure in your fishing gear use a piece of electrical tape on your rod as a maker and measure the fish length when you get home.

Image above: Paul Fuller with a tagged Mangatutu Stream Rainbow.

Keep your released fish alive by treating them well

Many of the trout that are killed by anglers in the Auckland/Waikato Region don’t end up in the smoker. It is not uncommon for trout to die from the impacts of stress after being released. Imagine if you were forced to exercise in 40° heat to the point of complete exhaustion and then were immediately suffocated for 30 seconds. Odds are not all of us would survive.

There has been a lot of research on the survival of released trout and some more commonly discussed factors like treble hooks play a relatively minor role in fish survival. The big killers are exhaustion, heat and suffocation (time out of water).  Trout that are caught in water temperatures above 19°C have a 20-30% mortality rate and fish that are held out of the water for 30 seconds to take photos or to remove the hook die about 30% of the time even in relatively cool water temperatures. The combination of exhaustion, warm water and time exposed to air is likely to be lethal. Most Waikato streams breach 19°C during the summer and the Mangatutu Stream has ranged from 16-20°C during the last month so if you release trout and want them to survive, please:

1. Move upstream to avoid fishing in areas where water temperatures are >19°C.
2. Fish in the morning to avoid peak temperatures.
3. Don’t remove fish from the water if possible.
4. If you do take a photo, consider leaving the fish partially submerged.  

Theoretical impact of time out of water and warm water temperature on trout.