Can trout spawn in stillwater ponds?
Yes, trout can spawn in lakes and ponds. Even in ones without inlet or outlet streams. The spawning success rate is low, but it is high enough to sustain populations of wild trout.
When given the choice, trout prefer to spawn in clean gravel beds beneath clean, cold flowing water which is oxygen rich. They also tend to prefer shallower rather than deep water. This gives the fry the best chance of hatching. But, what about trout living in lakes and ponds, where do they spawn?
Pond trout still try to seek outflowing water for spawning, this is usually a small tributary or even the outlet.
I occasionally fish in a hydroelectrical storage dam. The resident trout, every winter gather at the mouth of the canal. There the swift and cold canal water spreads thin and creates ideal spawning conditions. They always seem to prefer the shallow and slightly slower water at the mouth over the swift and deep canal.
Now, not all ponds have inlets or outlets.
Some ponds just have muddy and swampy margins and no clear flowing winter. Where do these trout spawn?
Well, life always tries to find a way to survive and trout are no exception. Stillwater trout are more likely to spawn close to freshwater eruption zones such as springs. Even better if there is suitable gravel nearby.
Spawning can also occur deep within lakes where there is upwelling from bottom fissures. The latter is typical of spawning in many volcanic-region lakes in Iceland where water flow is underground.
Trout and char of the world. Bethesda, Maryland: American Fisheries Society.
While writing this article, I suddenly thought of a small Brook Trout pond. This pond has no inlet to speak of, there is a feeder stream, but it mostly flows underground. The outlet again is an inconsistent swamp, far from suitable spawning habitat. Yet, the Brook trout population, despite no stocking for years remains stable. The Brooks must be able to find enough clean gravel to successfully spawn.
If no such spring exists, out of desperation trout even spawn on the lake shore, relying on the motion of the waves to keep the eggs oxygenated. I have not seen this firsthand, but apparently, it is a fairly common occurrence on many Scottish Lochs and Irish lakes.
Spawning of lake-resident S. trutta occurs on shoreline gravels where there is sufficient wave action or diffuse water flow from the surrounding land to provide oxygenation. This type of spawning is typical of many small upland lakes
Population genetics and Genetic Stock Identification of anadromous Salmo trutta from the Irish Sea and adjacent areas, using microsatellite DNA loci. In G. Harris (Ed.), Sea trout: Management & science
These loches typically have cool, windy conditions and plenty of rain. There are even reports of sea trout favoring spawning on gravel beaches rather than the inlet streams.
Will trout spawn in a private pond?
A question often asked by anyone who recently stocked trout in a private pond, is whether they will spawn and maybe even become a self sustaining population.
To be honest, this is very unlikely to be the case. Firstly, many stock trout are infertile. Even if conditions were perfect they are not going to produce viable eggs. Secondarily, Most private ponds lack clean gravel and cool enough water for spawning to successfully occur. Trout might still try and spawn, but the eggs will not hatch due to low oxygen levels.
If you want trout to spawn and reproduce, it is essential to have clean gravel with a steady supply of clean and cool water flowing over it. This can be challenging to achieve in small, isolated private ponds.
