Fishing in the Central South Island Region.

Graeme Hughes, Fish and Game Officer

Christmas New Year holiday fishing
With the traditional summer holidays all but over, they will probably be remembered for the most inclement weather experienced for many years, some say at least forty! The rain fall has been quite phenomenal and as a result the rivers of the region have been high and for much of the time discoloured. When conditions allowed trout fishing has been described from good to excellent. The information received so far makes it difficult to specify which waters have been the most productive. In the southern part of the region the Hakataramea, Maerewhenua, Ahuriri and Tekapo Rivers have all been good producers. To the north good flows remain and as happens on these occasions, with maximum food production the brown trout becomes well fed and more difficult to catch. The Waitaki River has been high for several weeks and “didymo” has been troublesome with the water column full of dislodged algae from small strands to large mats weighing several kilograms. The high flows and the huge amounts of “didymo” drifting downstream is affecting the angling effort to such an extent that if salmon were entering the river there is every chance they will migrate upstream without seeing an anglers lure.

The Rangitata River is producing some of the best salmon fishing anglers have experienced in a number of seasons. The total number of salmon caught at the mouth this season is closing in on 200 fish and as at the 15th January around 40 have been caught in the last four days. The fish are in great condition, most around 7-8kg with the occasional larger one being landed. It provides anglers who have given up salmon fishing in recent years the motivation to dust off their gear and wet a line again in the hope of securing a salmon.

“Didymo” Prevention
The combined forces of ECAN, DOC, Biosecurity NZ and Fish and Game have been active in the fight to stop the spread of “didymo”. Cleaning stations have been constructed and are situated at Kurow. Omarama,Twizel and another ready to be installed at Glenavy. With large signs instructing the user they should be easily seen and hopefully used. Three 120 litre drums supply a salt solution, a detergent mix and a water rinse for anglers and boaters to ensure they are not responsible for spreading this invasive algae.
Fish and Game Officer Graeme Hughes assisted the DOC holiday programme with a presentation on Didymosphenia geminate, or “didymo”.
A sample of substrate from a river not affected was compared with that from a “didymo” affected river. Whereas the clean river, the Hakataramea River. produced many hundreds of mayfly and caddis and juvenile brown trout, on average, 3030 invertebrates per square metre, the Waitaki sample provided several small snails.Prior to infestation the average of aquatic invertebrates recorded in the Waitaki River averaged 1100 per square metre.

“Didymo” Research
In conjunction with Southland Fish and Game Region Central South Island is assisting NIWA in exploring the apparent effects of spring ground water on “didymo”. There is an obvious dislike of this water by “didymo”. Where ever spring fed streams enter an affected braid the algae is absent and does not appear until the flow becomes diluted with the snow/rain fed water a short distance downstream. It seems reasonable to assume that the chemical makeup of the springfed water includes some trace element not found in the river water which precludes the growth of “didymo”. The next step would be to identify this difference. To achieve this in an acceptable and scientific manner is not a rapid process, however we are part way there and have the algae growing on artificial substrates upstream of the springfed streams. The next step in the process is to move the substrates into the influence of the unaffected tributaries. Prior to this however there are many samples to be collected which will be analysed in NIWA laboratories. While this work may not lead to a “cure” it is an exciting discovery and any new information on Didymosphenia geminata is good information.

Boat Fishing Seminar
A boat fishing seminar was held in Omarama during the holdays attracted 85 people and from all accounts was very successful. Organised by Otago Fish and Game Region and using local and a North Island speaker all aspects of fishing for sports fish from boats were covered. The different methods which can be employed, including weighted lines and “down riggers”, the use of “fish finders”, to the little known technique of jigging for trout were discussed. Inquiries from anglers who did not attend but wanted to know when the next seminar is indicates that the worth of this free seminar has spread by word of mouth. An experienced boat angler said that he had picked up some interesting tips which he will be trying on his next outing.

Law Enforcement
Unfortunately the weather played havoc with a programmed ranging exercise in the Ashburton lakes. On the day we targeted two inches of snow fell at the Lake Heron camping ground. Lake Benmore ranging on 28 December was very successful but equally disappointing. Considering it was the second consecutive year we have been there between Christmas and New Year we had more non-compliance than last year. While we did not strike any who admitted to not having a licence at all, we did find 20% of all anglers were not carrying their licences. I suspect a few of the FTP’s (failure to produce) will turn into unlicenced fishing prosecutions.

Ranger Training February at Temuka
The weekend programme has been split into two standalone days. On the Saturday we will undertake coordinated ranging on the coastal rivers.
On Sunday three outside presenters have been arranged. There will be an update on Didymo by Shirley Hayward from Canterbury Regional Council covering recent research into control, monitoring surveys to track its spread and CRC role in the didymo response. Tony Shaw, our Solicitor will cover lessons to be learned from recent prosecutions and in the afternoon we will be instructed in firearms safety and handling, particularly of shotguns, by the NZ Mountain Safety Council. This will culminate in certification on the Arms Code which is a recognised qualification for Health and Safety requirements.

World Record “Rainbow”?
A 16.3kg Rainbow trout was caught near a salmon farm located on the Wairepo Arm of Lake Ruataniwha. Caught by a 9 year old angler on 6 kg line, if officially weighed on accredited scales and accepted by the International Game Fishing Association it will be a world record catch in this line class or any line class recorded in the IGFA record book. The present record in this line class stands at 13.18 kg (29 lb 1 oz) caught in the Skeena River Canada in 1976. The largest Rainbow trout officially recorded by the IGFA weighed in at 14.41 kg (31 lb 12 oz) and was caught on 3 kg line in Santa Cruz Lake in New Mexico, USA in 1999. It must be the week for big fish as another monster “rainbow” was caught in the Ohau River which flows into Lake Ruataniwha a few days earlier. Although no scales were available to accurately weigh the fish it was estimated to be between 12 and 15 kg.