North Canterbury Fishing Report Friday 27th April 2018

The fishing season is all but finished now and with rain forecast for much of the region this weekend, are rivers are likely to become discoloured for a few days, so last minute prospects for the weekend ahead don’t look great.

The main rivers should be salmon fishable tomorrow morning and there may still be the odd salmon about, more so the Waimakariri, and there will be one or two spots still worth a look this late in the season before they become closed for salmon fishing at the end of April, next Monday. 

Above right: Hydra Waters in the Rakaia headwaters, ideal salmon spawning and rearing habitat.

Remaining salmon will be waiting for the next fresh to head up to their spawning grounds. Salmon spawning surveys are underway and angler salmon harvest phone surveys are about to begin and the general consensus is that we have had yet another poor season.

Staff carried out their first aerial salmon count in the headwaters of the Rakaia on Sunday, and were disappointed with the numbers observed.

Only 220 spawning salmon were counted. The Rakaia itself was discoloured and any salmon waiting below their spawning streams were not visible, however a number of spent salmon carcasses were observed in each of the streams, indicating we are nearing the peak of the run, which appears to be a week or so earlier than usual this year.

Further counts will be carried out over the next few weeks.

While we are not entirely sure what all the factors are that determine the size of the run each year, all the east coast salmon rivers show similar trends in returns, indicating variables at sea are the main driving force in survival.

There are however a few variables in the freshwater stage of their lifecycle we can have an influence on.

Environment Canterbury and Fish & Game have recently completed a three year study, looking at the differences between a number of salmon spawning streams in the Waimakariri, Rakaia & Rangitata rivers, investigating whether there are any adverse effects from farm intensification in the Canterbury high country on the significant salmon spawning streams.

The project monitored in-stream habitat, recording substrate composition, invertebrate sampling, macrophyte and algae monitoring, along with collection of water samples for chemical analysis.

As well as water quality, the health of a stream is affected by the type of habitat on the stream bed.

In particular, ecologists are interested in the amount and type of algae and periphyton growing on the bed and the amount of fine sediment present.

A healthy stream has a diverse range of invertebrates present, which feed on a fine layer of light brown algae growing on the gravels.

Fish & Game staff use a bathyscope to monitor the

Increased nutrients in streams encourages growth of less favourable algae types. Build-up of fine sediment on stream beds also has a negative impact on stream invertebrates, filling in the cavities under the gravels and reducing habitat.

Once fine sediment is in a spring fed stream, it can take a long time to flush out (or may never) due to stable flows.

While many of the streams studied are likely to show near pristine habitats, some are also likely to show impacts from farming, and this data provides an essential baseline for reference in future years.

Monitoring also provides a valuable opportunity to involve the landowners when gathering the data.

For some time now, Fish & Game have expressed their concerns to ECan about the state and effectiveness of fish screen designs and their operation in Canterbury, as well as their maintenance and compliance with consent requirements.

Many of the fish screens in Canterbury were designed and installed prior to the completion of overseas scientific work on fish screen design and the subsequent development of guidelines and standards to ensure screens conform to current best international practice.

Even on screened intakes, fish rescue operations at the end of the irrigation season often yield in excess of 1,000 sports fish each year.

The design of any fish screen should be such as to enable migrating and resident fish, safe passage past the structure.

A successful fish screen requires various criteria to be taken into account at the design stage, with all individual parameters required together to ensure the effectiveness of the screen.

Fish & Game continue to work with ECan, to ensure their compliance and monitoring staff are familiar with the various parameters required for fish screens to work effectively. 

Most anglers have packed their fishing gear away until next season (many of whom are eagerly awaiting the opening of the gamebird season on Saturday 5^th May), however for those keen anglers that cannot wait until next season, there are a number of rivers open all year in the region.

Following a short closure in May to allow salmon uninterrupted spawning, there are also a number of lakes opening again in June.

Please check your regulation booklet,  or the North Canterbury Fish & Game website for regulations on these waters. https://fishandgame.org.nz/assets/Uploads/Fishing-Regs-SI-2017-19.pdf

The winter season offers a special opportunity for anglers keen to brave the elements on these high country lakes. Winter fishing is often overlooked by anglers, but this is a great time to head into the high country to fish, with snow-capped alps in the background, calmer weather and the low number of anglers about at this time of year, there can be some very enjoyable days out, but make sure you dress warm!

The most popular spot in the region is Lake Coleridge which has fished well during the winter months in recent years.

This is a great opportunity to get your boat out onto the lake on a clear day, with a popular technique to troll a bright coloured sinking Rapala, many anglers lure of choice throughout the year.

Later in the winter season, salmon fishing usually really fires up with some weighing up to 2kg caught in recent seasons, which is relatively large for Lake Coleridge.

There are also a few large Rainbow trout in the lake with a number of 2-3kg Rainbow caught each season, which is well above average for this lake. 

This is the final fishing report for the season as we head into the game bird season.

Please have a look at the Sports Fishing Regulations booklet if you do intend fishing during the winter, as there have been a number of changes in recent years, making it difficult to remember everything.

Good luck if you are heading out over the last weekend of the season.

Steve Terry, North Canterbury Fish & Game Officer