North Canterbury Weekly Fishing Report 8-12-17

  • North Canterbury
  • 8/12/2017
  • Richie Cosgrove

North Canterbury Weekly Fishing Report 8-12-17

Bio-security alert in the North Canterbury Fish and Game Region

Due to a worrying bio-security concern in our region, the focus of this week’s fishing report will be on informing all anglers about what is happening.

It is certainly with regret that I am having to report a bio-security alert in our region, rather than talking about fishing prospects for this weekend.

The reality is at the moment, there is nothing more important.

While we are hoping for the best, we are treating this as a serious freshwater fisheries bio-security matter and will be regularly updating you as licence holders on what is happening.

These updates will be on the Fish & Game website

NC Rash2Thanks to the vigilance of a trout angler, we were alerted last week about rainbow trout in Lake Grasmere with an unusual looking rash on their underbellies, extending up the flanks of the fish as pictured on the left.

The angler also reported there were many other fish swimming unusually upright, with their tails sticking out of the water.  Others looked sick and lethargic.

Fish and Game responded immediately to the reports, consulting with the Ministry for Primary Industries (MPI) Marine Incursion team.  Fish & Game staff were sent to Lake Grasmere to gather samples of affected fish.

Four fish caught showed similar symptoms, three rainbows and one brown trout.

Samples taken were chilled and immediately sent to MPI’s Wallaceville lab near in Upper Hutt.

As a precaution, Fish & Game closed lake Grasmere along with the neighbouring Lake Sarah.

Fish & Game has also notified anglers about what was happening, sending an email to 108,000 licence holders that we have an email address for.

There has also been media coverage of the issue.

A decision was then made to expand our sampling to other lakes in the area as a precaution.

FGNZ NC LakeHawdon+MarymereFishSurvey131Following an angler report, Lake Hawdon was sampled on Tuesday this week and fish there also showed the same unusual marks.

Lake Hawdon also showed some severe signs of environmental habitat stress, including the discovery of unusual looking algae.  These are now being tested by Environment Canterbury (ECan). 

Following the Lake Hawdon results, Fish & Game had no choice but to assume that all lakes in the area were affected so a decision was made to extend the closure to the following lakes: Marymere, Hawdon, Pearson and Lyndon as well as Lakes Sarah and Grasmere.

ECan staff have joined Fish & Game staff to take temperature readings in Lakes Pearson and Grasmere.

The water temperatures were also recorded as high, 23 degrees for the first seven metres, then dropping to 13 degrees below that depth in both lakes.

A factor of interest in the area is that light, or no winds, and very warm temperatures have been a feature over the past two weeks.

All fish caught have been in great physical condition besides the rash markings, and minimal to no surface feeding activity by trout has been observed despite great hatches, and terrestrial activity evident in the lakes. Perfect fly fishing conditions!

The lakes will remain closed until we have ascertained what we are dealing with.

The Wallaceville lab tests may take up to four weeks before there is a result.

From the initial findings at Lake Grasmere, Fish & Game both nationally and driven locally by the team at North Canterbury Fish & Game have taken very serious and immediate steps to protect our fishery.

All fish transportation and releases were immediately suspended, all hatchery and on-growing sites are in lock down to protect them, all kids fishing events which involve fish transportation at the Groynes and this Sunday at Lake Lyndon have been postponed.

Until we know what we are dealing with, all sampling has been done under strict bio-security procedures.  This means a rigorous and invasive decontamination regime after site visits, including the use of disinfectants, bio-security signs, protective gear and cleaning procedures.

We have to think the worst until we know better.

In the meantime, we are continuing to gather information - water temperatures, dissolved oxygen levels, water tests, algae samples, reports from anglers are all being recorded and taken into account.

Next week the sampling programme will spread wider so we can be sure that we have this issue contained within the Waimakariri Lakes.

We will also enforce the current closure areas.  All locations are clearly signposted, so there are no excuses - our entire fishery is potentially at risk if we don’t keep the area isolated.

Fish & Game has no control over other recreational activities, but as responsible anglers, we all have a responsibility to advise all other recreational water users of the current situation.

We are encouraging anglers to report anything unusual about their catch - pay close attention to the under belly and eyes of the fish.

Do not put a fish back if it shows any sign of sickness, or physical signs of irritation, dis-colouration, inflammation, or unusual marks such as lesions or blisters.

Some symptoms may be very obvious, some may be in the early stages.  Keep these fish if caught and contact Fish and Game immediately.

The above information is there for you to share.

Make sure anyone you talk to, angler or not, is aware of the situation and the potential bio-security risk. 

We ask that everyone does their bit by keeping away from the area, or at least, out of the water. 

North Canterbury Fish & Game Office: 0800 347 426 or

Tony Hawker 021 221 8325

Dirk Barr        021 2218378

Dirk Barr, North Canterbury Fish and Game Officer.


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