$350k pro­ject to boost spawn­ing

South Canterbury Herald - - OUT & ABOUT - ESTHER ASHBY-COVEN­TRY

A new $350,000 up­grade at Lake McGre­gor will help to re­store the spawn­ing area for brown and rain­bow trout to its nat­u­ral state.

Over the past six years the Lake Alexan­d­rina Con­ser­va­tion Trust has cleared and re­laid the fish spawn­ing area.

Trust chair­man Alis­ter Clarke said the site along the creek that runs from Lake Alexan­d­rina into Lake MacGre­gor had been over­run with weeds and wil­lows over the years.

‘‘It’s a big process (recre­at­ing the site) with a big 20 tonne dig­ger dig­ging out half a me­tre then lin­ing the space with rocks so the (trout) don’t get in the silt and spawn.’’

Two hun­dred tonnes of spawn­ing shin­gle was then placed on top of the 300 tonnes of rock.

It was cheaper to pur­chase the spawn­ing shin­gle from Pleas­ant Point than Tekapo so it was carted up.

Shin­gle al­lowed oxy­gen to pen­e­trate where the fe­male have laid their eggs, he said.

What was a 90 square me­tre spawn­ing area be­fore the work started was now 900sqm, al­low­ing the fish to spread out more, Clarke said.

The trout fish­ing sea­son is from Novem­ber 1 to the end of May, but a ma­jor dif­fer­ence in the amount of fish may not be no­ticed for a few more years.

How­ever the num­ber of redds has dou­bled from 20 three weeks ago to 40 last week.

Redds are the mounds on the shin­gle floor cre­ated by the fe­male trout bur­row­ing about 35mm to pro­tect the laid eggs.

They also made it easy for the trust vol­un­teers to es­ti­mate how many fish would likely hatch, with a 50 per cent suc­cess rate an­tic­i­pated from ev­ery redd.

‘‘The lake is spring fed so there are no floods. What we do will stay in­tact for the next 20 years,’’ Clarke said.

The cost of the pro­ject was funded with $150,000 from the Macken­zie District Coun­cil, $27,000 from Pub Char­i­ties and the re­main­der through trust fundrais­ing ac­tiv­i­ties.

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