I'm a total ignoramus regarding Sea Trout - I'm a bit confused on when and where they are in terms of river and estuary / moving up to spawn etc at different times of year?

When is spawning time, I've read various opinions relating to floods and frosts as well as some confusing stuff about them running up rivers in spring and summer (is this for a different purpose) does all this vary on location and river type?

If anyone can pop me onto a definitive link, or can spare the time to explain, then much appreciated.

Thanks,

Splash

But that said, I'm really looking forward to the answers.
fae

Fred, that's the weight of two behind my query - don't feel so daft asking it now.

It's one of those 1/4 to 1am (GMT) questions that you ask yourself, when you should be heading for some zzz's, just thought I'd put it out there for a change.

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Great answer, they are fascinating.

Sounds like they are a fickle bunch, it will be interesting to hear from other locations.

Can I assume they are in the river when food is more plentiful and are spawning following climatic triggers, in order for their young to catch the spring and warmer season, allowing better survival?

Bound not to be that simple I'm sure!

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I'm risking turning toddler like saying 'why, why, why' here!

Well oxygenated gravel, I ask myself how does that occur?

Presume that is via a location on the river that naturally suits the trout / sea trout because of good flowing oxygenated water over a natural gravelly bed that is suitably stable to sustain / punt on raising the nippers?

... and, might it just be located up a river, probably just by chance at a certain distance and place due to local geology, nothing more or less than water run off / normal river lifespan / development, that sculpts the process, then this just happens to suit spawning fish?

i.e. if the nursery looks cosy / right for the kids, then it gets used?

If next year one shuts down and another opens up that looks more fit for purpose then nature takes a shift and the nursery shifts?

Might have taken a few hundred if not thousand years previously perhaps or maybe not, this must be a constantly changing process?

wow,what a can of worms!! but nice to see someone with obvious questions!
ok here we go.
migratory fish, ie salmon/sea trout, and to a certain degree brown trout, will always try to return to the spawning grounds of their birth. that is why specific tributaries of rivers can expect a run of salmonids at specific times of year, and often before main river runs arrive, if river bed of their birth has changed due to natural processes, ie floods moving gravel beds, or man made, ie obstructions, they will find the most suitable areas downstream of their place of hatching, never upstream, as they are in unfamilliar terrritory upstream.
This principle is very noticeable if hatcheries on rivers put eyed ova into rivers at various points, resulting hatched fish, if they return, will not move past areas they were hatched in!
and yes you are right, the return and spawning of salmonids has been going on for millenia in spite of us humans doing our utmost to finish them off.
as to other points in first thread, sea trout and salmon will, and do, come into river months before they spawn, perhaps looking for a head start or best areas, however they wont spawn until photoperiod (daylight hours) and water temperature suits them, hatching spawn also depends on water temperature over a period of time before they hatch ie "degree days" so in some instances eggs will hatch quicker some years than others. in general sea trout and brown trout spawn first october/november followed by salmon november/december, but this varies geographically.
regards
bert

Many thanks Bert, I am getting a really good picture this end from all the above, it's like a crash course for 'Dummies'.

I am applying the advice above to a very real river I know reasonably well, in particular to a place where I've been told that Sea Trout visit but have never seen any myself (to my knowledge), haven't tried all that hard mind you.

Also considering the affects of how I've seen more silt build up in one particular gravel section over just a short while and weed forming where it didin't before etc, plus what appears to be rapidly changing shapes of smaller gravel beds from year to year and assessing how they would navigate up from the estuary etc - all just out of curiosity really.

I am going to have to chuck in the obvious next question on your input though - a bit cheeky, but as I've been allowed to ask the basic ones so far, why not keep them rolling ... others might be wondering as well?

...if they never go upstream past their place of birth and if the beds are washed out / pushing them downhill, doesn't that mean that eventually all fish will be pushed out into the estuaries, game over for spawning?

The 'chicken and egg' question follows on from that one - how did they get up into the rivers in the first place (before anyone throws in another response suggesting space aliens or something, we should ask that they keep it scientific )?

Splashtest nothing is written in stone Some fish will always try to get further up river, you can see this clearly enough at any impassable waterfall or weir.

They got up into the rivers in the first place by swimming up from the sea into them. Remember that during the ice age there were no fish in most (if not all) of what we now call the British Isle for the simple reason that there were no rivers. Everything was buried under ice. As the ice retreated the rivers would have be re-colonised by fish taking advantage of new habitat. Some, for some reason, lost the urge, ability or need to run to sea and these are our brown trout.


Andy