Why don't we get more big trout in coarse waters?

[lutra]

Planning a trip ferox fishing this spring and got to wondering why we don't get more very big Brownies in some of our coarse waters, some of which must have many more times (than a deep and cold Scottish loch) small bait fish for them to get big and fat on.

 

So why do ferox favour these deep cold places?

Edited December 20, 2011 by lutra

[Chris Plumb]

So why do ferox favour these deep cold places?

 

Access to Arctic Char?

 

 

C.

Edited December 20, 2011 by Chris Plumb

[lutra]

Access to Arctic Char?

 

 

C.

Yes, but whats wrong with roach, rudd, dace, skimmers,...............?

Edited December 20, 2011 by lutra

[Vagabond]

Good question Lutra

 

As Chris says. arctic charr may be part of the answer, but it goes "deeper" than that (pun intended, sorry )

 

If trout are in cold and deep water after charr, then they may be safe from the attentions of pike. My impressions of pike in deep lochs is that they rarely are caught in water deeper than 30 feet - suggesting they stay within that depth. OK, I don't get the opportunity to fish deep lochs very often (once a year) so my experience is limited.

 

Do regular fishers of deep lochs for pike know any different ?

 

By contrast, southern lakes and reservoirs are relatively shallow, so there is no part of them into which pike won't go. Trout seem particularly vulnerable to pike predation (think of all those huge pike taken in trout reservoirs) hence I suggest five pound trout readily fall prey to 30lb-plus pike and miss their chance of growing bigger

 

Just an idea.....

 

Now I have succeeded with an English charr, I will be joining Lutra in his search for a big ferox, and expect to get a pike or two while doing so. I expect we will learn something about the interactions of pike, trout and charr on the way

[Steve Walker]

Some information on optimal growth temperatures in brown trout;

 

http://books.google.co.uk/books?id=g2CTQtz...p;q&f=false

 

Other thoughts:

 

The switch to piscivory - is this driven by environmental factors, perhaps the lack of alternative food sources? There is a phenomenon in tadpoles where starvation conditions lead to a minority of the tadpoles becoming cannibalistic. Their jaws change shape and they grow much larger and faster than normal. Is the switch to fish eating in trout driven by similar factors?

 

Is the tendency to switch to some extent genetic?

 

Are conditions in coarse waters conducive to long life in brown trout?

[Anderoo]

Some of the English reservoirs are pretty deep in places (I think Rutland goes down to about 120ft?) but I would hazard a guess that the main factor in producing ferox trout is food availability. In the lowland reservoirs, even the deeper ones, there is plentiful insect life and fry, which may mean that the trout aren't compelled to switch to the only alternative food source of small-medium sized coarse fish and become completely predatory.

[Vagabond]

Norma and I were discussing this over our evening meal of Dingo Chicken (barbecued and torn apart with the fingers)

 

Another reason - few natural lakes in Southern England so maybe the tendency to produce a proportion of ferox has diminished (still survives as the odd cannibal trout of the Thames and the chalk streams)

 

The man-made reservoirs of the south are stocked by hatchery-bred trout - could this domesticated strain have had the ability to throw up the odd ferox, (and even seatrout?) bred out of it?

Edited December 20, 2011 by Vagabond

[Vagabond]

, there is plentiful insect life and fry, which may mean that the trout aren't compelled to switch to the only alternative food source of small-medium sized coarse fish and become completely predatory.

 

Good point, but chalk streams, despite the abundance of invertebrate life, still produce cannibal trout.

[cannibalspinners]

Good point, but chalk streams, despite the abundance of invertebrate life, still produce cannibal trout.

Up here in scotland trout thrive in our lochs with good flowing feeder burns in to them

these burns produce plenty insect life which inturn feeds small trout

So the loch is naturally stocked with a rich food source for trout

hence they grow big

also a lot of our waters are vast

Miles long , Miles wide & hundreds of foot deep

I reguarly fish for pike at St marys loch

in the Scottish borders

it is 3 miles long 1/2 mile wide

& 150 foot deep in places

in winter i have dead baited to round about 70 foot

& caught pike ,So they too lie deep

The real large trout up here have NO enemies except man

no pike will go near a 25lb + Trout

Have you seen the size of the head on a large ferox trout

They look very mean beasts

Even my 7lb+ River brown trout had a head on it like a pit bull

[Latimeria]

I've wondered about this one for a good few years, the big Lancashire ressies should be good for thisl, they nearly all have native stocks of brownies in the feeder streams and ample food. You've got fairly deep, well oxygenated water, and given that the Irwell and its tributaries are producing some pretty big trout there's no barrier from the climate or genetics. They must be there, perhaps in low numbers, Ant Glascoe had a superb fish while piking a few years ago (can't remember which ressie).

Might be competition from pike meaning there's no exclusive territory, might be an absence of food at depth during the Summer meaning they have to come shallower and compete with pike (but don't think so, the ressies fish well for coarse fish at all depths for me in Summer), might be that angling pressure means that most of those that move down out of the feeder streams get caught while still in lower single figures (and it might be a one-way trip to the bank). The feeder streams might be unsuitable for large fish to run back up to spawn which prevents those individuals from increasing the genetic tendency to go big and bad, might be that they are there but people are not fishing right for them (dropped runs for pikers or getting bust up on feeder gear and blaming a pike for grabbing a hooked fish), might be that they are in such low numbers (might only be one or two a year that make the switch from the streams to the main body of water) that the chances of encountering one are low, Summer draw-down might lower oxygen levels and territory below a critical level for them. There are probably a few more potentia reasons I've thought about in the past and forgotten.