Rainbow Trout Spawn

[damaltor]

I was reading some comments the other day, regarding rainbow trout and whether or not they spawn in lakes. One member posted the following and it's got me scratching my head?

"When they (rainbow trout) are put into lakes they are the same sex. Trout can adapt and change sex but with people keeping and them dying over the winter due to low oxygen levels they don't spawn"

If there is any truth to this, then I've really missed the boat when researching various trout species?

[chriscosta]

I've been told they need to swim upstream to spawn and if they can't they won't ... not sure how true it is tho ...Also I think stocked trout physically can't spawn ...again not positive of any of this

[AlbertaCutthroat]

Rainbow trout cannot change sex and generally do not spawn in lakes. I say generally because they do often go as far as building redds along shorelines and some years when the conditions are right (water stays cool late enough in the spring) some eggs will hatch. I know of confirmed reproduction by hatchery rainbows in at least 1 Alberta stocked lake last summer, lots were emerging from the gravels at about 2 cm long and a couple biologists did document it. Neat but very rare.
Triploids (3 sets of chromosomes) are being stocked more and more which reduces incidental spawning further, though in a hatchery setting triploid does not mean 100% success, some diploids (spawners) will inevitably still be present. Grass carp are the only fish stocked 100% triploid in Alberta as fish are individually tested to remove any chance of spawning.
Rainbows require clean gravel with moving water (wind can work in rare instances, generally creek inlet or outlet is what produces high numbers of fry) and cool temperatures (until fry emerge) to reproduce. Most lakes do not have these habitat features therefore are managed strictly for harvest following stocking.

[fish gunner]

Great post ^^^ a few documented cases of lake spawning rainbow exist one in BC one in the UK and one in NZ im aware of. these lakes have springs under clean gravel and the fish appear to be quite ssuccessful whit self sustainig populations.

[Deer]

Rainbow trout taste super good

[damaltor]

Interesting info guys. Although rainbows naturally need to spawn in streams, it seems logical that if they found the same conditions in a lake, they could be sucessful spawning there too.
Regarding the stocking of lakes with females only, I do not believe this to be true? And I do not believe rainbow trout or any trout for that matter, are able to change sex. I can find no documentation that even suggests this is possible.

[Riverbc]

Regarding the stocking of lakes with females only, I do not believe this to be true?
Yes it is true. They are neutered, and called Triploids. If you look at BC's stocking reports, these fish are designated. AF3N...All Female...3 sets of chromosomes....neutered.

"Triploid (3n) Technology
The use of non-reproductive technology in hatchery production has direct benefits to the fishery and protects wild fish populations. This technology involves a sterilization process that is unique to each species of fish. Such treatments increase the cost on a per-fish basis, but the fishing benefits can be substantial. Currently approximately 50% of the small lakes in BC are stocked with triploid fish. FFSBC produces triploid rainbow trout, eastern brook trout, kokanee, and cutthroat.

Benefits of Sterility:
triploid fish can potentially live longer than diploid fish
natural post-spawning mortality is reduced
can result in a higher number of larger “bright” fish being available to the fishery
has the advantage of reducing the risk of potential genetic interactions between hatchery and wild fish and/or preventing the establishment of hatchery populations in areas of conservation or biodiversity concerns.
One misconception about triploid fish is that they are Genetically Modified Organisms (GMOs). Triploid fish are not GMOs. Genetically modified animals are organisms that have had their DNA molecules altered by genetic engineering. Triploidy is a condition that can occur naturally in salmon and trout (albeit at very low rates) that makes the affected animals reproductively sterile. Currently the FFSBC induces triploidy through the application of hydrostatic pressure, or heated water to the eggs shortly after fertilization. This technique results in the retention of the second polar body normally extruded shortly after fertilization. This results in the retention of a third set of chromosomes instead of the usual two sets. This triploidy method achieves a 98-100% sterility rate in our facilities. The result is sterility in both males and females. Through this relatively simple pressure shocking process, no genetic material is introduced, moved or taken away. The fish are not “genetically modified” in any way.

All-Female (AF) Technology
The creation of an all-female population of fish is labour-intensive. The FFSBC produces all-female populations of fish by crossing sex-reversed females with normal females. To create sex-reversed females normal fry are exposed to testosterone derivatives to halt ovary development and produce normal testes. These "masculinised" females remain genetically female (XX) but functionally male. The sperm must be extracted by hand as these fish generally do not develop a sperm duct. Once mature they are crossed with normal XX females to create all-female progeny for release.

An all-female stock has benefits over a mixed sex (male and female) stock in that it takes advantage of the slower maturation in females which means more time available to the fishery. Over 80 percent of males in some stocks exhibit precocious maturation (or “jacking”). These males mature during their first season in the fishery and have a high post-maturation mortality, lower flesh quality, and an overall smaller fish size. In addition, the stocking of all-female progeny in the absence of males effectively creates a functionally non-reproductive population.

All-female Non-Reproductive (AF3n) Technology
The production of AF3n fish for stocking derives the benefits of both the process of "feminization" and triploidization (AF and 3n). Sterilization manifests itself differently depending on the sex of the fish. Female triploids are hormonally and functionally sterile (i.e. no development of functional oocytes (eggs), and no behaviour changes). Male triploids are sterile, but still produce hormones that cause changes associated with maturation including deterioration of flesh quality, early mortality, and the development of testes and other secondary sex characteristics. In addition sterile males demonstrate "false" spawning behaviour including migration and interactions with other fish on the spawning beds regardless of their inability to reproduce. This behaviour can potentially displace wild functionally reproductive males possibly reducing the fitness of the wild population.

The double treatment (AF3n) for stocking programs further reduces the risk to wild fish since the females will not display “false spawning”. AF3n ensures that if there is a small percent of individuals for which the tripoidy process did not occur that the stocked population would be functionally unable to spawn by virtue of the fact that all progeny are females."

[Icatchfish]

I caught 3 inch rainbows at chain lakes last ice season I pretty sure they spawned In that lake

[dryrush]

I caught 3 inch rainbows at chain lakes last ice season I pretty sure they spawned In that lake

I have also caught/found many smaller trout(6" and smaller) in stocked lakes including the lakes in Calgary communities

[damaltor]

Riverbc... Very interesting and informative info there. I should have mentioned that this comment was made regarding the stocking of lakes in AB. I do beleive that some of our lakes are stocked with triploids, but most are not.

[Riverbc]

Sorry ... Sometimes I forget where I'm posting.

[damaltor]

Icatchfish & dryrush... I would think it most likely that if you are seeing fingerlings in these lakes, that the rainbows are heading up the feeder streams and spawning there. I know of one lake in fact that is self sustaining and has browns in it, the browns are not spawning in the lake but traveling up the inflow to the lake to spawn.

[goldscud]

dryrush...can you tell me which community lake you saw these baby "trout"?

Willow Creek flows into the SW corner of Chain lakes. Most likely there are some fish migrating up the creek to spawn

[chriscosta]

I seen a few smaller than six inches at my favorite pond..and i gauruntee theres no stream and its a muskeg lake no gravel..i bet the get in there when stocking happens...it is a bot off key there tho i caught a trout about 12 inches or so and when i cut him open i seen a giant like 2 inch long grub or maggot so i just had to get it out..curiosity ya know..and to my suprise it was a white 2 tail walleye jig lol no hook to be found ...so its probly not good to throw them in the lake unless attached to your rod..but imagine that catching trout on walleye gear ... wth right

[Northern Yaker]

I seen a few smaller than six inches at my favorite pond..and i gauruntee theres no stream and its a muskeg lake no gravel..i bet the get in there when stocking happens...it is a bot off key there tho i caught a trout about 12 inches or so and when i cut him open i seen a giant like 2 inch long grub or maggot so i just had to get it out..curiosity ya know..and to my suprise it was a white 2 tail walleye jig lol no hook to be found ...so its probly not good to throw them in the lake unless attached to your rod..but imagine that catching trout on walleye gear ... wth right

Harvesting 12" fish really. Wow that's quite a meal.

[ksmitty]

Well here's the size of a lot of fish that were stocked in alberta this year.

[chriscosta]

Harvesting 12" fish really. Wow that's quite a meal.
Lmao ... for god sakes man it was for my kid ... but like it matters ...i myself dont eat trout ..but aNyWaYs...trout spawning??what?

[Rikkles Fisher]

Harvesting 12" fish really. Wow that's quite a meal.

Oh the things I would like to say to you buddy, not getting into it though.