February 2009 Reel Life, Central South Island Region.
Graeme Hughes.

 High flows deal to Didymo
The Waitaki River is the focus for many anglers  as they impatiently wait for the annual salmon run. Due to high inflows to the major storage lakes, Lakes Pukaki and Tekapo , a steady rise from 250 to 300 cumecs to a high of 950 cumecs negated any thoughts of accessing known salmon holes. Even if access was available the very turbid flows created by removal of silt and erosion of the many islands battered by the current would prevent any fish, salmon or trout, sighting a lure. Many anglers would have been happy to know that the increased flow should be doing something nasty to the didymo which has made life difficult for the  last 2 seasons. A cruise down the river at resumption of normal flows showed that the didymo had in fact taken a fair hiding and I guess perhaps 90% of it had been cleared from the main braids. In some of the more stable side streams , those areas which did not receive the full force of the flood flows,  didymo is still firmly attached to a narrow bank side strip of substrate. The jet boat trip was quite a revelation. To see the Waitaki cleaned of didymo from an aesthetic perspective showed me how I took the old Waitaki for granted and how you miss the simple things, clear water bouncing over riffles, accentuating the colours and reflection of light , the deep blue of pools and swift running guts.  No matte brown, bank to bank carpet of didymo, no didymo in the water column and no floating mats of didymo which can put a jet boat of action in moment . Although re-colonisation has already begun there will be a timely respite to river anglers which should coincide nicely with the upriver migration of salmon.

Didymo  before spilling of 950 cumecs   The same braid after high flows

Salmon fishing .
The Rangitata River is enjoying a good run of salmon but  low clear flows decreasing to only 50 cumecs have probably saved a few. The rain which is still falling at this time have solved the problem with the river presently flowing at 180 cumecs having peaked at 360 cumecs.  As it clears the catch rate should improve markedly.

The Waitaki River has had a slow start which will hopefully culminate in a good ending as it has done in the past. Although the Waitaki River is rarely discoloured the rains over the last few days have swollen the tributaries and as a consequence the water is turbid  and unfishable. With the hydro storage spills followed by the flooded tributaries salmon anglers are not having a great time. This will not prevent salmon moving upstream which should provide a multitude of fishing opportunities when flows and water clarity return to normal.

Floods are timely
The Waitaki River tributaries,  namely the Hakataramea and Maerewhenua Rivers, have experienced extremely low flows of less than a cumec which necessitates  netting and electro fishing of drying pools. The rains arrived at a most opportune time and they have been transformed with high flows. It is probably unreasonable to expect the trout stocks to increase at this time of the year however if levels remain, above 2 cumecs would be ideal, there should be good access for migrating salmon. Low flow in the last years have limited salmon access into spawning tributaries. The first salmon historically appear in the Hakataramea River during the first week of April.

Smolt releases.
Due to the generosity  of Sanfords Ltd,  42000 salmon smolts were released into Lake Benmore, 26000 released into Lake Opuha and 3000 into Lake Hood. Lake limited salmon are usually in the fishery for 2 years before they mature, however during that time they create considerable interest amongst lake anglers. A day on the lake when trout are not cooperating can often be saved by hard hitting “Chinooks”. They don’t get an opportunity to grow to sea going proportions  but they make excellent table fare and many a BBQ plate has baked these great eating fish during the holiday period. 

 
Salmon smolts are released to their new home at Ohau “C” in Lake Benmore

Sockeye Salmon
Sonar surveys and netting in the Haldon Arm of Lake Benmore this month indicate that Sockeye salmon should run up the tributaries in the next week or two. The males were beginning to develop the red colouring and some exhibited the humped back common amongst several species of pacific salmon. Sockeye are always referred as small salmon, of interest was the size of the salmon this year. Having observed and monitored salmon since the late 70’s these would be the largest sockeye I have seen. They have done particularly well which is most likely food related. As plankton feeders, one of the reasons you and I can’t catch them in the lakes, there must be an increase in the plankton population to provide the apparent weight gain. From a sample of the salmon caught Mark Webb who weighed, measured and then had  the messy job of otolith collection,  tells me that the largest  sockeye he handled had a fork length of 465 mm  weighed 1336 gm; that’s almost 3lb in fisherman’s language. Larger fish should mean more ova deposited and more juveniles many of which will feed the lake’s trout population. Surprisingly the sockeye and numbers of trout were recorded and caught at a depth of 29 metres, a depth where using traditional trolling methods an angler’s lure would seldom reach. 
 

 A migrating female “sockeye caught” (and then released) in the lower Ohau River. 

Hatchery releases planned.
Some 70,000 of the 90,000 Chinook salmon fingerlings reared at the McKinnons hatchery will be held until July. Fin clipping of all stock will begin in March before release. 20,000 fingerlings will be released in stages at Ealing springs and the 2,500 originating from upper Rangitata stock will be released in the north branch of Deep Stream a spawning tributary of the upper Rangitata River. 

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