49lb Rainbow!

[Chris Plumb]

http://tinyurl.com/l8cdl4

 

 

 

C.

 

Err that should have said 48 lb!

Edited September 18, 2009 by Chris Plumb

[Steve Walker]

I think it's a bit misleading to describe as triploid fish as "genetically engineered to grow extra big", it's just a triploid, as commonly stocked in the UK. Triploids are made by heat-shocking the eggs at 26-27C for 20 minutes shortly after fertilization. Genetically engineered or genetically modified implies transgenic to me, which these fish are not.

[lutra]

I think it's a bit misleading to describe as triploid fish as "genetically engineered to grow extra big", it's just a triploid, as commonly stocked in the UK. Triploids are made by heat-shocking the eggs at 26-27C for 20 minutes shortly after fertilization. Genetically engineered or genetically modified implies transgenic to me, which these fish are not.

I was expecting some tailless balloon shaped monster, but what ever it is, its a great looking fish.

[Steve Walker]

Nine years in the wild since it got out of the fish farm, apparently.

[lutra]

Nine years in the wild since it got out of the fish farm, apparently.

I'm guessing it wasn't very big when it slipped under the wire so that's pretty impressive weight gain. But what ever its weight on escape it must have jumped out of the fish farm and landed in a sweet shop.

[Steve Walker]

True - it is a big water, though, at 43,000 hectares it's six times the surface area of Loch Lomond, and I suppose it's ecologically close to native habitat for rainbows (if draining to the wrong seaboard) . Not the first massive rainbow to come out of there, either.

[Vagabond]

I liked the captor's response to criticism -

 

"Stop crying and start fishing"

 

[corydoras]

I'm guessing it wasn't very big when it slipped under the wire so that's pretty impressive weight gain. But what ever its weight on escape it must have jumped out of the fish farm and landed in a sweet shop.

That is the whole idea of washing the eggs to make the fish a triploid. Fish genetics are a wee tad different to mammals. Mammals, like you and me get one half of our genetic make up from our mother and the other from our father. A fertilised fish egg always starts with two sets of genes from the female and one from the male, thus all fish eggs start off as triploids. Normally the egg rejects one set of genes and becomes a 'normal' diploid. Sometimes however the egg kind of 'forgets' to kick out the extra set of genes and the fish becomes a perfectly natural triploid. However, triploids are neither male nor female, they have no gonads and so the gain the weight much more quickly than their diploid siblings. When you wash newly fertilised fish eggs in warm water you inhibit the egg from rejecting the spare set of genes and the resulting offspring are all sterile triploids. No 'genetic engineering' required, just a bath of warm water.

[lutra]

That is the whole idea of washing the eggs to make the fish a triploid. Fish genetics are a wee tad different to mammals. Mammals, like you and me get one half of our genetic make up from our mother and the other from our father. A fertilised fish egg always starts with two sets of genes from the female and one from the male, thus all fish eggs start off as triploids. Normally the egg rejects one set of genes and becomes a 'normal' diploid. Sometimes however the egg kind of 'forgets' to kick out the extra set of genes and the fish becomes a perfectly natural triploid. However, triploids are neither male nor female, they have no gonads and so the gain the weight much more quickly than their diploid siblings. When you wash newly fertilised fish eggs in warm water you inhibit the egg from rejecting the spare set of genes and the resulting offspring are all sterile triploids. No 'genetic engineering' required, just a bath of warm water.

Interesting stuff cory.

 

My experience of with escapee triploids in large UK waters (Scottish lochs and large lakes and reservoirs in the north of England) is that they do well to even maintain their escape weight and Ive always been under the impression that escapee browns fair better. Even on waters like loch Awe (home of the record UK wild brown trout) which have had plenty of escapee triploids over the years, Ive never heard of them doing that well.

 

It would be nice if someone could point out I'm wrong though.

[Steve Walker]

I guess the question is why they do so well there and so poorly here - they grow very large in the wild in the US, and although they are native to the West coast, there are spawning populations in the Great Lakes with impressive growth rates:

 

"In forage-rich Lake Michigan, they grow 30-32 inches long and may reach 16 pounds by the time they are five years old"

 

http://www.seagrant.wisc.edu/greatlakesfis...inbowtrout.html

 

Possibilities that occur to me -

 

Perhaps our waters are just too small for them.

 

Perhaps our climate doesn't suit.

 

Perhaps the strains of rainbow trout grown here have been selectively bred to be effective pellet-pigs, not to forage and grow in the wild. Are we comparing wild boar with escaped domesticated pigs?