September Round-up

Winter fishing.
In the Waitaki Valley fishing pressure on the lakes probably increased due to the better weather, lack of snow and importantly a lesser number of “norwesters”.
Night fishing in the vicinity of lake tributary inflows was  rewarding unless a good frost set in and casting a fly rod became difficult due to ice build-up on line and rings. Still if you picked the right night anglers could hook up to 20 fish landing about half of these. One keen angler interviewed  claimed that in 12 outings he had landed 74 trout. That’s a good average!

Spawning trout numbers encouraging.
In the Waitaki Valley known spawning observations again indicate runs of “browns” have been excellent, better than last year and although still early in their migration period, Rainbow trout numbers observed so far are encouraging. In the Aviemore Spawning race. 235 brown trout  redds were counted. (229 redds were counted in 2006). After almost 40 years of use by brown and rainbow trout (and sockeye salmon prior to 1980) construction of redds by salmonids has caused the unavoidable downstream movement of gravel. As a man made construction it works very well but there is no replacement of gravels as would occur in a natural stream. In parts of the upper race fish have excavated down to large cobbles. Re-gravelling race will restore the race to the 1968 specifications and will help reduce redd superimposition which is prevalent.

Sockeye salmon  runs, an exciting resurgence.
Previous reports indicate that this little known species has enjoyed a resurgence which took most freshwater fisheries people by surprise. Their recent runs can only benefit the overall health of the valley sports fishery either by providing an alternative forage fish for trout or being available to the angler adding variety to the three species bag which some lakes provide. It is possible for an angler to catch a Brown trout, a Rainbow trout, a Chinook salmon and perhaps now a Sockeye Salmon. More reports of anglers taking “sockeyes” emerge, some anglers caught and released small salmon thinking they were Chinooks however it appears they were most likely Sockeye salmon.  There has been an increased interest in the species and there have been numerous inquiries from anglers, the most prevalent being how do you catch “sockeye”? As far as the writer is aware the catch of “sockeye” has been by anglers trolling traditional trout lures and targeting lake trout. It appears it is where and when you fish which will dictate if a sockeye will strike. Sockeye are early spawners and ascend lake tributaries in February and March. Trolling in the Haldon Arm in and around the inflows of hydro canal at Ohau “C”, the lower Ohau River and the Tekapo River during these months may result in hook up with a Sockeye salmon.
Fishing for them in the spawning streams will, with persistence, catch a “sockeye” but on their last leg of their journey they are not an exciting fish to catch and the flesh is very poor quality.

Chinook Salmon
The Chinook salmon run picked up during the last two months and with the shortened season there was some concern amongst anglers that the regulation should have been revoked because of the encouraging numbers migrating into the  Waitaki River. Of course we disagree. With the increase in run size and a decreased season duration, the number of ova deposited and the resultant hatch should be higher which should increase the salmon run to come three years from now. Time will tell. There is no question that if you take  spawning salmon out of the run there is absolutely no future benefit excepting a few cans of fish in the pantry which will soon be consumed and perhaps a photograph in the album. 

Despite the  shorter season angler surveys show that the catch rate on the Waitaki River for the 2006 / 2007 salmon season was the best for the last 3 years. (This applied to the Rangitata and Rakaia Rivers also). Angler surveys indicate that just under 500 salmon were caught in the Waitaki River.
An aerial salmon survey in May revealed Chinook salmon spawning from about State Highway 1 bridge to just above Kurow and 1014 redds were counted.  Despite redd counts providing less than accurate adult  fish numbers, estimates combined with the anglers salmon catch indicate there could have been  2000 to 3000 salmon enter the Waitaki River during the spawning run.

In the Rangitata River, angler harvest was estimated at 950 salmon with a total run of 3170 salmon,  the highest count for 8 years

Shortened season returns to conserve spawning salmon.
In the mid 1990’s, 20,000 to 30,000 salmon were taken from South Island rivers by anglers. In the last 2 or 3 years the total catch has been estimated at only 2000 to 3000. Anglers will note that in the Waitaki, Opihi, Orari, Rangitata and Ashburton Rivers, fishing for salmon will again cease on the 31st of March. Anglers may still fish for trout however by giving salmon an extra month of protection it will hopefully increase the number of mature fish reaching their spawning grounds. This early closure is the second year of a salmon conservation plan which will remain in place for at least three years as it will take this long to see any affects the regulation may have.

Short salmon season equals increased salmon hatch.
During the last season Central South Island anglers caught an estimated 1620 salmon with a 95% confidence interval of +- 410 . Had the season remained open throughout the month of April it is estimated a further 400 salmon would have been caught. These fish however continued their spawning run and deposited close to 1 million eggs in the gravels of their respective rivers. If in the calculations anglers other than CSI are included, the estimate of extra ova deposited could rise to between 1.25 to 1.5 million.

Didymosphenia geminata.
It will be an interesting if not trying year for anglers and fishery managers. With the invasive diatom “Didymo” in many of our rivers, the unanswered question for many of us is how long will it be until we see an effect on the region’s fish stocks. It is already affecting the way we fish however at this time there is no noticeable affect on fish inhabiting infected water and in fact, information received in angler diaries indicate trout condition factors have shown a slight improvement for both species. Diaries also show however, a significant decrease in hours spent in fishing the Waitaki River, presumably because of the presence of “Didymo”. From last summer’s experience, it appears after a period of higher flows, 400 to 500 cumecs, the algae was shortened and the amount drifting downstream lessened significantly. This resulted in less cleaning of line and lure and made fishing much more pleasurable 

The Kauru River, a tributary of the Kakanui River is closed to angling in an attempt to prevent the colonisation of “Didymo” into this river which is a stronghold for the critically endangered lowland longjaw galaxias.
Rangitata River tributaries, Deep Creek and Deep Stream, well known salmon spawning waters, remain closed for trout or salmon fishing  all year.

A New Season Ahead
Opening day, 1st of October, falls on a Monday and there may be a few employees late for work or perhaps others “off sick” due to this most inconvenient starting day for the new season.  For many the season is not really open until the first Saturday in November when all high country waters open, excepting the upper Ahuriri River, tributaries and tarns.

Incorrect date for High Country opening.
The printer must  have been looking at a 2006 calendar when printing the 2007 / 2008 Sports Fishing regulations. As most will be aware the opening day for High Country fishing in the CSI region  is the first Saturday of November and the first Saturday in December for the Upper Ahuriri River, tributaries and tarns. These dates fall on the 3rd of November and the 1st of December, not  the 4th November and 2nd  as printed, these dates are Sundays. 

The season closed last April after what can only be described as an exceptional trout fishing season and for salmon, closing in March, a catch rate which had greatly improved. Undoubtedly, many anglers pondered on what might have been had the season closed on April 30th.

We are often asked “What’s the season going to be like?” or “Plenty of fish about?”. The second question is a lot easier to answer, the first is an unknown  until the season is over. Are there plenty of fish abou? The many waters of the region produced good results throughout last summer and there are no indications at this time that there should be any change. 

The lakes are well stocked and are continual providers year after year. A winter netting operation to gather a sample of trout for toxicology testing, showed that the lakes fished equally over the same net hours fished. The most intensively fished area, usually by boat anglers, is the Ahuriri Arm of Lake Benmore. Our net catch showed why. This arm of the lake produced the largest trout and best conditioned trout.

The rivers are more difficult to gauge, however those that suffer less due to low flows in the height of summer remain good providers. Ultimately it depends on the enthusiasm, knowledge and skills of each angler. The world’s most notable angler Izaak Walton said “Angling may be said to be so like mathematics that it can never be fully learnt.”

Tight lines.
 
Graeme Hughes
Fish and Game Officer
Central South Island Region.

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