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Trout Stripping

Fast Facts

'Stripping' is what they call it when they catch trout and 'strip' them of their eggs and milt (sperm). Below you can follow Taupō Fishery rangers as they go through this process.

Why are we doing this? Two reasons:

  1. At Tongariro National Trout Centre there is a Kids' Fishing Pond where people can go to catch kids. Wait, no, where kids can go to catch fish!
    The purpose of the pond is so that rangatahi (young people) can have a chance to catch a trout by fly-fishing. It's aimed at getting you into fishing! But to fill that pond up with trout, they need to come from somewhere - so we raise thousands of Rainbow Trout in our hatchery.


  2. The other reason we raise trout in our hatchery is in case of some kind of catastrophe wipes out the Taupō trout fishery - we'll have lots of healthy trout with good genetics to re-stock the system.

You can also see a video on the process here.

1. Assess the trout

Rangers Jeremy (L) and Tim (R) check the trout to ensure they are 'ripe' - ready to lay their eggs or milt

These rainbow trout have been trapped in the Waihukahuka Stream next to the Trout Centre

2. Anesthetic

Trout are placed in a gentle anesthetic to make them calm during the process.

Once the trout is sleepy enough, the stripping can begin.

3. Strip the hen

The 'hen' is the female trout. Jeremy is stripping the bright orange eggs by massaging along her body.

4. Strip the jack

The male 'jack' has milt, or sperm, which is needed to fertilize the eggs. A similar massaging motion releases the milt.

5. Combine eggs + milt

Jeremy is gently mixing the eggs and milt with a feather so that all the eggs are fertilized.
The fish are back in freshwater while they wake up, then they will be released into the stream again.

6. Rinse and rest

After 2 minutes the eggs are rinsed in stream water to remove the milt.

The eggs are gently poured into a bucket with water, and sit for around 60 minutes undisturbed to 'harden'.

  • Why might it be important to get young people interested in fishing?

  • Why do you think they are only stripping rainbow trout?

  • Is anybody allowed to strip trout? Why/why not?

  • Rangers rinse the eggs after mixing with the milt - so fertilization must happen pretty quickly. Why would that be the case in trout?