hi all just a quick question do farmed rainbow trout produce roe i always thought they were sexless cheers

Only Triploid trout are sexless,all other Trout will enter the spawning cycle.

jim

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Normal rainbows are often bought in because they are cheaper to produce. Just to change the subject a little, I have had sterile wild browns on a few occasions from our rivers in the past. Early September, Lower Eamont, two identical brown trout, caught within minutes of each other on dry fly, no milt, no roe present, both 1lb 12oz, both surely mature. I should have had them checked out --will if it ever occurs again. TC

When trout spawn, the female’s eggs possess two sets of chromosomes and the male’s sperm possess one set. After the eggs are fertilised, the chromosomes recombine and each egg inherits one set of chromosomes from the female and another set from the male — similar to humans. The third set is then kicked out of the egg. Rarely in the wild, an egg will “forget” to kick out the third set and the fish becomes what is known as a triploid (possessing three sets of chromosomes). Triploid fish look, swim, jump, and taste like normal fish, except for one important difference—they never develop normal eggs or sperm and are unable to reproduce (i.e., they are sterile).

Through experimentation with this natural process, researchers found that they could create triploid trout both by exposing trout eggs to pressure and by placing trout eggs in a warm water bath shortly after fertilisation. Both processes inhibit a trout egg’s ability to kick out that third set of chromosomes and voila, a triploid fish is born.

Funny that I have caught rainbow trout with eggs in from C&K fisheries, where the owners swear the fish are triploid.
So maybe triploids do produce eggs/roe, but that they will not develop normal eggs.

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Cheers
Wiz

www.wandletrust.org
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Staying a little bit off subject for a bit.
Sterile or just not spawning that year?
Kingsmill Moore mentions the possibility that well conditioned fish taken from big Irish loughs in February and March were ones that had not spawned that winter.
R. Greer in his book on ferox says that they don’t spawn every year and gives examples of ferox taken in late season with no developed eggs/milt.
A proportion of sea trout on their first return (peal/finnock/herling) don’t spawn. I’ve had a number of cock sea trout (coincidentally all around 1lb 12oz) in October over the years that had no developed roe, the reproductive organs were there but had not started to ripen. They clearly weren’t going to spawn that winter. Of course I can’t say that these fish would have spawned in following years (the ones I caught certainly didn’t, I ate them!) and they may have been sterile, but I don’t think they were. Either way it is food for thought.


Andy

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The process to make Rainbows ( like everything else in life) is never 100% sucessful , so you may still get alledged triploids producing eggs or milt.

Cheers

Jim

Not quite true, a fish that hasn't succesfully been made triploid will always be female. It's impossible to triploid a male so the eggs are always 100% female at fertilisation to get maximum triploids.

HI, EXE,
Yes, I take your point, the same thought was at the back of my mind, maybe the fish that I caught had just decided to skip a broody season. That was what prompted me to say, partly, that I should have had them checked out. TC