Local Govt | National News Video | Parliament Headlines | Politics Headlines | Search

 


Looking for the ‘X factor’ in fish

IMMEDIATE RELEASE 18/6/2014

Trout are spawning and its ‘talent time’ – looking for the ‘X factor’ in fish

It’s spawning time on the Rotorua lakes – when a few trout heading upstream find themselves hauled off into a fishy talent show!

Fish & Game staff know exactly what they’re looking for as they trap fish and screen out the biggest and best trout for their Big Fish Breeding Programme. These hand-picked (literally) specimens are the breeding stock used to raise more than 100,000 fish to keep North Island lakes stocked up for anglers.

The fish are trapped as they swim upstream to spawn – in a stream that flows into Lake Tarawera, known for its hard-fighting trophy trout. They are carted off to holdings pens in a stream which flows through Fish & Game’s Ngongotaha hatchery grounds.

A set of selection criteria are used to pick only the best fish as parents – a female to supply the eggs and “cross” with a male that’s used to fertilise them. The aim is to produce fish which are healthy and grow rapidly to a large size for anglers to catch.

Most of the fish used for breeding are three year-olds, along with a smaller number of four year-olds which are breeding for the first time. Trout stop growing once they reach maturity and spawn, so by selecting older maiden trout for breeding the hatchery improves the chance of their offspring growing bigger.

Previous spawners are often rejected because they have poorer quality eggs and these, Fish & Game officer Lloyd Gledhill explains, can be picked by signs such as the ragged edges on their fins where they’ve been digging redds (nests) in the gravel.

This year the largest fish appear to be around the 65cm to 68cm mark, so fish which are over 62cm fit the selection category for the time being. “Later in the season we might change the selection size depending on how the run is going. You never quite know how many fish might come in, and once they have been through the trap it’s too late to get more.

“If we don’t get eggs now, there’ll be no fish to release next year so the pressure in on” says Mr Gledhill.

After selecting for size, it comes down to a “judgement call” on the look of the fish. Mr Gledhill says you get fish that are different shapes including those which are “all head and shoulders” and tail off to the back. “I like a fish that’s a much more even shape all the way through. We look for robust, healthy fit fish.”

Fish & Game staff aim to end up with 135,000 viable fish, which means stripping an estimated 250 thousand eggs from the “ripe” hens. Every spawning season they “cross” a total of about 90 males with the same number of females, 180 fish in total.

“That gives us a good margin – some eggs die and others die at hatching so that gives a good number of viable fry at the end. It also ensures we get good genetic variety in the fish being released to the lakes.”

How are the eggs extracted? The fish are firstly sedated in a fish bin with a synthetic clove oil added, then a small gauge tube is inserted into the fishes belly cavity, and compressed air used to gently push the eggs out.

“The sperm activates as soon as it hits the water – so you’ve got about 20 seconds for the sperm to get to the egg and fertilise it.”

The eggs are taken inside the hatchery and placed into trays with running water piped over them, to begin the process of growing first into first “eye ova,” and then into fry.

When they’re big enough, the young fish are loaded into the ‘live trout truck’ and carted off for one of the many releases into North Island lakes.


© Scoop Media

 
 
 
 
 
Parliament Headlines | Politics Headlines | Regional Headlines

Last Sitting Day Of Parliament: Slave Ships Bill To Pass

The House resumed at 9am and MPs agreed to add the third reading of the Fisheries (Foreign Charter Vessels and Other Matters) Amendment Bill to this morning’s business.

The bill requires all foreign owned fishing vessels to fly under a New Zealand flag from May 2016 and obey all New Zealand laws. This includes labour laws...

Last night Opposition MPs accused the Maori Party of blocking the passage of this bill into law in this Parliament, no members of the Maori Party were in the House to answer the accusations though they denied this in a press release. More>>

 

Parliament Today:

Novopayout: Government-Owned Company To Take Over School Payroll

After lengthy negotiations, the Ministry of Education and the existing school payroll provider, Talent2, have settled both on the amounts payable by Talent2 towards the costs of remediating the Novopay service and a new operating model for the school payroll system. More>>

ALSO:

Employment: Labour Will Raise Minimum Wage, Restore Work Rights

A Labour government will raise the minimum wage $2 an hour to $16.25 and restore work rights to ensure the benefits of economic growth are shared fairly by all New Zealanders, Labour Leader David Cunliffe says. More>>

ALSO:

Police: Crewe File Review Released

No new evidence has come to light implicating any specific person as being responsible for the murders of Jeannette and Harvey Crewe... The review identifies there is a distinct possibility that Exhibit 350 (the brass .22 cartridge case) may be fabricated evidence, and that if this is the case, that a member of Police would have been responsible. More>>

ALSO:

Werewolf Issue #49: Gordon Campbell Interviews Laila Harre

For 25 years, Labour and National have been in virtual agreement about the basics of economic policy, and differed mainly on how to go about managing its social consequences. More>>

ALSO:

Greens: Plan To Protect Our Maui’s Dolphins

1. Protect Maui’s from being killed in the sanctuary set up to protect them... 2. Extend fishing protections to the entire Maui’s range... 3. Help protect the livelihoods of affected fishers by supporting them to adopt dolphin-safe fishing methods. More>>

ALSO:

Gordon Campbell: On National’s Electorate Deals

For all the talk yesterday from Prime Minister John Key about National being transparent about its electorate deals in Epsom and Ohariu, that transparency is entirely front-loaded. More>>

ALSO:

Greens: Oil Drilling Face-Off With Labour

The key policy points in the Green Party’s plan to protect our beaches from oil spills are to:
1. Prohibit deep sea oil drilling; 2. Implement compulsory shipping lanes for coastal shipping; 3. Build Maritime New Zealand’s oil spill response capability; and 4. Introduce a stronger legal framework so that when accidents do happen, the New Zealand taxpayer does not have to pay for the clean-up. More>>

ALSO:


Nick Smith v Fish & Game:

Get More From Scoop

 

LATEST HEADLINES

 
 
 
 
 
 
Regional
Search Scoop  
 
 
Powered by Vodafone
NZ independent news