What's the deal with New Zealand ?

[Jessed]

Any one have any info on why the trout there are so big? I saw a video of a guy catching "small trout" in a tiny stream 5 feet wide and they were 17-19 inch Browns at a constant rate. Where's all the smaller fish? Then I was thinking well maybe the trout eat a lot of there young and smaller trout so that's why there's only big fish. But if that was the case why is there only ONE video where I saw someone throw streamers. I mean if I was gonna fish for a brown that's a good 8 pounds why not throw a streamer? Some of these fish in the rivers are just monsters.

 

[Jessed]

Plus and if the rivers are so prime for trout conditions why aren't there a species native to New Zealand?

 

[Dave_W]

I don't know why the fish in NZ seem so large on average. It may have something to do with lack of fishing pressure or natural predators (predation by adult trout on juveniles, as you suggest, may play a role too). I think NZ rivers are known for having relatively few fish, but large ones on average.

Brown trout were not native to the southern hemisphere but where they have been introduced into ideal habitat - think Patagonia - they have really thrived and grow to giant sizes. Sometimes when a fish species takes root in a new environment, their population really takes off and they grow to large sizes.

It's an interesting question and the answer is likely complex. Perhaps someone with more knowledge of the NZ fishery will chime in.

 

[afishinado]

Jessed wrote:
Any one have any info on why the trout there are so big? I saw a video of a guy catching "small trout" in a tiny stream 5 feet wide and they were 17-19 inch Browns at a constant rate. Where's all the smaller fish? Then I was thinking well maybe the trout eat a lot of there young and smaller trout so that's why there's only big fish. But if that was the case why is there only ONE video where I saw someone throw streamers. I mean if I was gonna fish for a brown that's a good 8 pounds why not throw a streamer? Some of these fish in the rivers are just monsters.

By world standards NZ trout are large. The obvious question is 'why are they so big?'

Basically it is due to a combination of factors: most importantly water temperature is ideal for feeding for about eight months per year (UK is approx 2-3 months). This combined with poor spawning conditions (Backcountry rivers are notoriously unstable) leave a few very large fish.

Link to source: http://www.sexyloops.com/nz/overview.shtml

 

[patapsco]

When I made my only trip to New Zealand in February 2015, and I arrived during a "mouse year." The year before, an important seed went into overproduction (as our acorns sometimes do) leading, in the next year, to an explosion in mouse populations. Every brown we took from the Wairu River was a good deal heavier, the guide told me, because they had all be feeding on mice. So that's one thing that helps these fish get so big. My largest was nine pounds, landed on a 590 Superfine Touch, of all things.

 

[gulfgreyhound]

Fewer fishermen. Less pressure. Low possession limits,one or two fish in most rivers. Guides practice catch and release. Lots of water to fish from small spring fed creeks to big rivers like TheDelaware,Pens creek ie. and lots that's unreachable unless you use a helicopter.
I fished quite a few streams and saw no one all day. I fished theClutha River and was the only angler in a stretch of river that had 500 trout per kilometer. I caught one about five pounds there.
Low population many don't fish or fish salt water..The South Island is rural with lots of big farms many have strict trespass policies. Get permission or stay out. There are good hatches and other food in the streams. The "mice years" or cicada years are bonus times when the big fish are active. GG

 

[gulfgreyhound]

Try: Forgotten Books.org. Trout in New Zealand by WHSpackman Ba .Published in 1892. Covers the history of the introduction of trout to New Zealand. Best part is that it' s FREE! Really amazing the effort that went into introducing trout here.
GG

 

[pcray1231]

Just like PA, to get big fish, you need either a massive food source OR you need a sufficient food source and a low trout population.

My understanding is that the latter is the case in New Zealand. The low trout populations is due to poor breeding substrate, and thus low reproductive success. Not due to poor habitat for adults, water temp issues, predation, harvest issues, etc.

With a low trout population, the few trout you do have, well, they have the pick of the habitat. They get to take up the prime feeding lies with no competition. Add in no predators and good year round temperatures, and those few fish are in the prime lies and doing nothing but feeding all year long.

 

[gulfgreyhound]

The food source is not an issue. Initral stockings in the 1800's put apex predators in environments full of bait fish and insects with no competition. I'm not sure what roll predation plays in the streams today, but the numbers of small fish I saw or caught were few. The stream bed seemed stable with lots of rocks for redds .
I still think it's a lack of pressure and tons of fishable water that let the fish get big. I've driven miles along streams and never saw a fisheman. GG

 

[pcray1231]

I've driven miles along streams and never saw a fisherman.

That's true of places in the good ole U.S. too. And the fish average much smaller for the size of the water even in such places.

Here's a good article.

http://www.wildflies.co.nz/articles/Biology%20and%20Distribution%20of%20Trout%20-%20Marc%20Griffiths.pdf

Most river-resident brown trout are found in the lowland portions of the river system where gradients are lower and flow rates more manageable for smaller fish. The flood-prone headwater and backcountry sections are generally inhabited by large fish, ranging between four and seven pounds. River-resident backcountry trout are able to attain these proportions, even though they feed predominantly on diminutive insect larvae, because their population densities are so low (often

 

[gulfgreyhound]

I question 3 a and b
I've seen numbers of fish in White Stone Creek that were in pools and stacked in runs and may have been fish from Lake Manopouri. I mean a dozen in two mile of creek. Very spookie fish.

Mice are just an extra as I bet the the "bullies' creek minnows and insects in the creek and terrestrials were the major parts of their diet.
I think most are fish that were hatched in the creeks and rivers and just grew big. GG

 

[pcray1231]

I think most are fish that were hatched in the creeks and rivers and just grew big.

Granted, but the question is WHY do they grow so big in smallish streams there, when they do not do so elsewhere in the world, even very remote waters that see very little fishing pressure?

but the numbers of small fish I saw or caught were few.

So where are the young ones?

 

[pro4mance]

If they were in the OT forum you'd probably know it. No offense intended, if you have to ask please don't

 

[gulfgreyhound]

This is a response from NZ Game and fish to an inquiry IO sent re: large trout.
The introduction of brown trout by the early Acclimatisation Societies began with the importation of trout ova (from Tasmania) into Otago in 1867. Up until the 1920s the early societies made a considerable effort to spread trout throughout the country. During this period migratory sea-run fish were also distributing themselves into new systems. In many regions sporadic liberations into rivers continued until the 1960s although it is now recognised that many of these were a wasted effort.

We are very fortunate in New Zealand in that the vast majority of our watersheds contain sufficient spawning streams with clean gravels. So the fisheries are self sustaining and the trout truly wild. In the Otago region we now only release trout into waters where there is no spawning habitat. A selection of small dams near Dunedin and throughout Central Otago. Our primary focus is now habitat protection. It is vital that we protect water quality and spawning grounds which are often at risk from land use intensification and sediment run-off in particular.

Trout released into virgin waters can grow very rapidly and the in the early days some NZ trout grew to tremendous sizes feeding on abundant native fish. Now the growth rates of New Zealand trout and the size obtained is largely dependent on population density and food resources available. In some North Island waters where there is no or very limited spawning habitat restricted stocking is employed to manage for large fish size. In Otago lakes with lots of spawning streams such as Onslow the average trout size is smaller (around 30cm) than systems with reduced recruitment such as Poolburn (average size around 52 cm). In some of my favourite streams such as the Shag and Waikouaiti Rivers the brown trout grow particularly well when there is a productive whitebait season. Whilst we are fortunate that our trout are able to obtain a relatively large average size on an international scale we do have fisheries such as the Teviot River with a small average age due to high fish densities.

Another factor that influences trout growth is the water temperature regime. Many of the large trout in cold headwater streams grew large in a warmer more productive lake system before taking up residence in a small stream. A life history adaptation that also enables some trout to grow large is longevity. While some of our headwater streams are relatively cold trout are still able to obtain a large size by simply living a long time, predating fish and reducing spawning effort. Large brown trout in some streams such as the Nevis River can be 10 or 12 years old. And I suspect that these trout are fortunate we do not have the big avian predators (eagles, fish hawks etc) that are present in the States.
GG

 

[pro4mance]

Mic Dropped by GG