Was given and extract from an article in issue 56 of the Target Taupo magazine by DOC from Didymo Dave. It offers a good reason as to the small trout size of last year and early this year though it seems to me that things on the improve. Have already had as many over 4 pounds as the whole of last year!

“However the phytoplankton concentration was unusually low in winter 2005. This low concentration was attributed to the incomplete mixing of the lake which usually occurs over winter when the surface waters cool. This reduces the density difference between the warmer surface waters and cooler bottom waters so that the agitation from winter storms with their high winds can mix the two layers. Mr Gibbs estimated that as a result of incomplete mixing as much as 50% of the nutrients (nitrate and phosphorus) remained in the bottom waters rather than being circulated up into the surface waters. The surface water is where nutrients can be used by phytoplankton (plants) and transferred through the food chanin to eventually reach smelt and trout. As a consequence the concentration of nutrients was lower in autumn 2006″

Tongariro Report

Barometer: Low

Cloud/Wind: Strong gusts

Water Temperature:

River Conditions: Clear to green

Recommended Flies: Size 14 Salmon Egg and Flame glow bugs.

Fished the Tongariro yesterday with my mate from TALTAC Peter Grange. We were down lower river and each hooked a few and landed a few with Peter landing one OK fish on the wet line. In general though, pretty much everyone now realizes that the average size this year is probably just under 3 pounds which is around a pound smaller than last year and is something that DOC really needs to research as to why. It could be natural or unnatural but will be in some way related to the predominant food source - smelt. In saying that the size is down, good numbers are still around and realistically in any other part of the world the fish would still be counted as huge - for wild fish. Its just that we are so used to being spoilt by large numbers of 4 and 5 pound plus fish on the Tongariro that 3 pounders dissapoint us.

There is some speculation from people that it is because with the 45cm limit we have been selectively culling the best breeding stock and leaving the smaller ones to breed. Whilst I agree that this could have an impact in some fisheries, it is unlikely that this would be the main cause as the drop in size would be a gradual thing over many years and not a sudden drop of around a pound on nearly every fish like we have had this year. By the way - in case any people reading this are against the killing of trout - I don’t kill or allow clients to kill fish in some rivers - just Taupo and Rotorua tributaries which are proven sustainable fisheries. I always feel that in wild fish environments trout will reach a balance in size more dependant on available food sources than on competition for that food source from other trout - though obviously an over abundance of trout in certain conditions could harm that food source. I don’t feel in most un-stocked rivers that over abundance of trout is a problem as floods and other predators keep numbers down.

There is no doubt that the fish are smaller this year - I would guess about a pound smaller on average i.e. I would guess the average to be just below 3 pounds. The only possible logical reason for this is lack of food in lake Taupo which would suggest that for some reason the smelt arn’t there in great size or abundance. DOC are trying to say that it is due to the fish spawning later and later but this does not make sence as the fish that were getting caught this time last year and in all previous years were a lot bigger. The fish have been around the same size for the last few months and I would predict the size to be quite small right up to September - the supposed new peak spawning time. How can you say the fish are getting smaller because they are spawning later and don’t have as much time to grow - 2 years is 2 years whether it is September to September or June to June! Either natural weather conditions will have caused the smelt situation or human factors like the posibility of fertilizers, herbicides or pesticides such as 1080 finally reaching levels that could be effecting algae growth in the lake or whatever smelt feed on. Noticably a lot of the fish arn’t exactly fat either!

Fished today with some friends from TALTAC all over the place and between us probably hooked around 15 or 20 for the day. Lots of other anglers around. Conditions are pretty good both in the Tauranga-Taupo and the Tongariro. I was disappointed to see other fishermen again fishing a lye that I thought no-one knew about - Oh well I guess I will just have to go fishing some more and look for some new lyes - its a hard life!