Large fish in New Zealand

[jerry]

I have been watching some old CDs about fly fishing in New Zealand. They are fishing small rivers, smaller than most rivers in the US. My question is this, they are catching trout that we would consider "trophy" fish in these small rivers. Do they have a different way of managing their fishery than we do. I think in England the gillies raise the fish in hatcheries until they are 4 or 5 pounds before they release them in the rivers and ponds.

 

[speyflyfisher]

I’m pretty sure those are lake run fish

 

[Matt B]

There are some insanely big fish in NZ “hydro canals” below or between reservoirs, but otherwise, from my limited understanding, just in general for their streams on both islands I think they grow large wild trout because of productive climate and water chemistry and geomorphic factors, but then also there is often limited spawning habitat that helps keep population densities low (and therefore competition is low), and, trout being non-native and all, there is a general absence of natural predators. So, big trout, not oodles and oodles of them, but nice trout, and some trophies.

WDFW and ODFW need to fix this disparity for their constituents by hiring the PNWFF A-Team to fly over there, capture as many of these trout as possible and fly them back here for release into PNW waters.

 

[Stonedfish]

What has always been interesting to me on the videos I’ve watched is the lack of large numbers of fish. I’m sure that happens but most of the time it seems a single larger fish is spotted and fished to. There are obviously enough to spawn and keep the populations going. I also don’t see a lot of small fish being caught.
Maybe I’m just watching the wrong NZ videos.
SF

 

[jaredoconnor]

NZ rivers tend to be relatively infertile, low fish density, little fishing pressure, not super high gradient, have abundant terrestrial life, etc. It’s the perfect storm for having one large fish in every stretch of water that is eager to take a cicada.

There’s plenty of small fish. They have to come from somewhere. They’re just not being shown on YouTube. Like many of our local rivers, the small fish are all up in the higher gradient sections.

 

[Chucker]

There are a wide variety of river ecosystems in NZ, from spring creeks with healthy populations of trout like you would find in the US, to almost barren high country streams that have the occasional small fish, if they have any at all. As Matt B says, the key factors that lead to large fish in some systems is low recruitment success and thus low competition between individuals and low predation on larger fish. There are also low rates of harvest in systems that are not near major population centers (because you can’t easily pack out a ten pound trout), so those big fish get caught multiple times.

As far as management goes, there’s a closed season and there are some harvest restrictions, but there’s almost no enforcement of those in most areas. All the fish in the backcountry streams are “wild” offspring of fish that were introduced a long time ago.