Sunday 21 August 2016

Road Trip 2016 - Day 39 (15th August) - Where are those Huge Murray Cod!!

So at 8.30 am we are down at Glenlyon Dam wall to see the promised huge Murray Cod in the morning light.

We were not to be disappointed - there were quite a few to be spotted hanging out along the margins of the dam wall where they can find good spots for spawning.

They were a long way from us (looking down from the top of the wall) - but with binoculars we could get a really good view.

I did also manage a couple of reasonable photos ---



You can see they are really very large.

We also see huge schools of "Boney Bream" which in this dam is the Murray Cods main diet


Some interesting info I have learnt, at the information point, today about the Murray Cod --
* The Murray Cod is a large Australian predatory carnivorous freshwater fish - mainly eating other fish for its diet
* It is the largest, exclusively freshwater fish, in Australia, and one of the largest in the world. 
In modern Australia, the Murray cod is nation's largest and best-known freshwater fish.  The stuff of legends, the Murray cod is represented in practically every pub in South Eastern Australia by photos and mounted examples. 
Today Murray cod are massively reduced in numbers.  Wild stocks are now estimated to be less than ten percent of the population present at the time of European settlement.  
Murray cod were originally extremely common and supported a substantial commercial fishery in the nineteenth century and in the early decades of the twentieth. Records from this fishery indicate that Murray cod were numerically the dominant native fish in the Murray-Darling system until the 1950s.
Murray Cod in larger waterways usually reach 90 to 100 cm and 15 to 20 Kg, if not taken by anglers.
The largest Murray cod ever officially recorded was 183 cm, 113 Kg (6 ft, 250 lbs), although there have been unsubstantiated claims for larger fish.
Murray cod are extremely long-lived.  Specimens regularly reach ages of 30-35 years.  The oldest specimen yet recorded is 48 years of age, but they almost certainly reach far greater ages, most likely as much as 100 years.  Extreme longevity is a survival strategy for many native fish and particularly Murray cod.  This enables them to outlast prolonged periods of drought, so as to capitalise on exceptional conditions for spawning when they do occur.
Spawning is initiated by pairing up and courtship rituals.  During the courtship ritual a spawning site is selected and cleaned — hard surfaces such as rocks in upland rivers, and logs and occasionally clay banks in lowland rivers, at a depth of 2 to 3 m, are selected.  The female lays the large adhesive eggs as a mat on the spawning surface, which the male fertilises.  The female then leaves the spawning site.  The male remains to guard the eggs during incubation, which takes 6-10 days (depending on water temperature), and to guard the hatched larvae for a further week or so until they leave the nest site (dispersal).  Larvae leave the nest site by drifting in river currents at night, and continue this behaviour for around 4-7 days.  
Murray cod have been stocked into many water reservoirs throughout the Eastern states. Some re-stocking of river populations has occurred but the most important tool in restoring cod populations to something like their former glory is the appropriate management of the river systems.  


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