Question about Stocked Rainbows

[waterninja]

In the past I have caught a few large female bows that were full of roe. I was told that even though stocked trout can't reproduce (males sterile) the females still produce and lay eggs. I think this was refering to "dipolids" that were stocked. Now that a lot of lakes are being stocked with "Triploids" do these females still produce eggs? Thanks.

Reason I'm curious, is in the past I have watched big male bows cruise around the "nests" that the females deposit thier eggs in, in order to eat the eggs. Nothing else seems to arouse thier interest.

[AlbertaCutthroat]

Unless something has changed very recently "triploid" rainbows in Alberta are not confirmed sterile as not every fish is individually tested. The only fish being produced in Alberta that are guaranteed triploid (each individual tested) are the grass carp. If they are producing what appear to be viable gametes they are most likely capable of spawning (if habitat for spawning was available). Additionally, many lakes now stocked with triploid rainbows were previously stocked with plain old diploids and therefore you will still see male and female fish capable of spawning.

[kirbstomps]

i was always led to believe that Rainbows needed cold running water to spawn and couldnt in ponds or small lakes. but i could be extremely incorrect....

[J D]

Originally Posted by kirbstomps

i was always led to believe that Rainbows needed cold running water to spawn and couldnt in ponds or small lakes. but i could be extremely incorrect....

correct along with gravel beds

[waterninja]

Originally Posted by AlbertaCutthroat

Unless something has changed very recently "triploid" rainbows in Alberta are not confirmed sterile as not every fish is individually tested. The only fish being produced in Alberta that are guaranteed triploid (each individual tested) are the grass carp. If they are producing what appear to be viable gametes they are most likely capable of spawning (if habitat for spawning was available). Additionally, many lakes now stocked with triploid rainbows were previously stocked with plain old diploids and therefore you will still see male and female fish capable of spawning.

By gametes, do you mean eggs, or roe? I know the females produce eggs, but always thought the males were sterile. Also I thimk they need running water as well as gravel bed (river, creek, stream). I was wondering if BOTH the diploids and triploid females produce eggs. thanks.

[Talking moose]

The eggs mean nothing if the right conditions are not met. ( enough flowing water rich in oxygen.)

[AlbertaCutthroat]

Originally Posted by waterninja

By gametes, do you mean eggs, or roe? I know the females produce eggs, but always thought the males were sterile. Also I thimk they need running water as well as gravel bed (river, creek, stream). I was wondering if BOTH the diploids and triploid females produce eggs. thanks.

Gametes = eggs or sperm. Triploids do not produce eggs though they are female in the chromosomal sense. Here is a slideshow from the states which explains it nicely.

http://www.az-tu.org/Triploid_rainbow_trout.pdf

As is also mentioned above, rainbows generally need flowing water to spawn though reproduction on windswept shorelines is possible (if temperatures stay low enough). There are a couple lakes in Alberta where limited spawning by stocked rainbows occurs during some years (many factors need to align for the eggs to hatch).

[waterninja]

Thanks for that link Albertacuthroat. States very clearly that triploids do not grow eggs. At least I'll know for sure if the trout I catch has eggs it is not a triploid.

[Brandonkop]

Yeah where I was fishing even in BC it is supposed to be stocked with all female triploids. Out of the 7 i kept and filleted they all were empty except one had well developed eggs. I would say that fish was not a triploid and rather a diploid. The process I hear is not a 100% complete penetration and some may still be diploids.

[goldscud]

Stocked diploid males will still produce sperm, so they are not sterile.

Triploid males will still color up and look dirty like a spawner and show some some spawning behavior(even though they are sterile).
Triploid females will stay nice and chrome