River wear 2021

BMiller

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Nice one Mr Miller.

Salmo trutta eggs can only survive at less than 3ppm salinity, if I recall correctly. I.e. Low salinity anyway.

Would this not suggest a trout, migratory or otherwise, is a freshwater fish adapted to salinity due to glaciation ? Also it appears that, in contrast to Salmo salar, full salinity is tolerated less well, especially at low temps - though there is contra expert opinion from Norway. E.G. I’ve never heard of a sea-trout being captured in the Greenland fishery, a stone’s throw from Iceland, which is renowned for its sea-trout. Plus sea-trout were not present originally in east-coast North American rivers.

Experiments at Scaliscro, Outer Hebrides, proved that when so-called river trout were starved they Became smolts. See AST Blue Book. I like this fit with sea-trout favouring tributaries as natal streams not always those in lower catchments, a theory held by some. AG
I understand that opportunistic migratory trout from rivers to the south colonised the rivers as they became available. These fish were anadromous and needed fresh water to spawn in.

Your note about starving river trout reminded me of a conversation I had with someone from the Lochaber area who had been trying to rear sea trout in a hatchery. He told me that this wasn’t successful because feeding the fry upset the smolting process. The reverse situation seems to happen in the Kielder Burn above the reservoir where sea trout smolts appear each year despite there being no migratory fish access for 40+years. Brown trout in a harsh environment producing migratory offspring.
 

Auldghillie

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I understand that opportunistic migratory trout from rivers to the south colonised the rivers as they became available. These fish were anadromous and needed fresh water to spawn in.

Your note about starving river trout reminded me of a conversation I had with someone from the Lochaber area who had been trying to rear sea trout in a hatchery. He told me that this wasn’t successful because feeding the fry upset the smolting process. The reverse situation seems to happen in the Kielder Burn above the reservoir where sea trout smolts appear each year despite there being no migratory fish access for 40+years. Brown trout in a harsh environment producing migratory offspring.Yes, rearing sea-trout was beset with problems. I think the Norwegians have cracked it now.

Possibly Irish and Baltic Sea-trout as well as French. See Queens Uni papers. I can’t fathom out the Baltic source though, must have been frozen solid until very late. I would have thought Rhine trout were a better bet.

I’m not sure if the Ailort is in Lochaber but my friend ran the restoration project there for Salar Properties in conjunction with Marine Harvest. Complete failure and since then aquaculture uses sea-grown rainbows in Scotland I believe. Salinity of Lochailort may have been an issue since the caged trout can’t seek freshwater of course. Seeking freshwater is what sea-trout do when injured or stressed. AG
 

greenlaner2009

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Sorry I disagree with the statement that browns chose to travel to sea to find a food source. Surely it is the other way round. Brown trout have historically found a food source in the river and choose not to go to sea. Ten thousand years ago NE England was covered in 100m of ice and as it melted and retreated rivers and lakes were populated by sea trout.
Ten thousand years ago the rivers we have now continued out across what was land between the UK and Europe, there was no north sea our rivers of the northeast coastline drained into what is known today as the Norwegian trench, this is the time when our seat trout where imprinted with the the area to head for to feed.
 

Lynnzer

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Ten thousand years ago the rivers we have now continued out across what was land between the UK and Europe, there was no north sea our rivers of the northeast coastline drained into what is known today as the Norwegian trench, this is the time when our seat trout where imprinted with the the area to head for to feed.
Ah that's when Brexit was conceived. The parting of the British Isles from the European continent.
Now if we can only stop the thieving gits from trawling British waters we might see an improvement in fish stocks, both sea fish and migratory
 

Auldghillie

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Ten thousand years ago the rivers we have now continued out across what was land between the UK and Europe, there was no north sea our rivers of the northeast coastline drained into what is known today as the Norwegian trench, this is the time when our seat trout where imprinted with the the area to head for to feed.
I doubt it, maybe the Living North Sea Project report might help you. AG
 

Auldghillie

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Good discussions...can you provide a link? I've never heard of the living north sea project, might be interesting.
I’ll try for you but if I recall it the project was joint between certain countries bordering on the North Sea so it’s long-winded.

The meat can be got from a piece from Dr Campbell of the RTC for the project showing sea-trout tagging results from Tweed/ Coquet I think. I’m not good with links, if you feel like it then PM an E-mail I can use, anonymous is fine.

The poster or respondent above might be correct so far as old migration routes but, for me, not the Norwegian Trench route. I say this because glaciation lifted earlier by decreasing latitude, which I assume is obvious. Also the trout would need to migrate under ice - an unlikely scenario in my eyes. There was a huge ice-cap over Scandinavia and Scotland down to c the Wash. Then the Rhine broke through Doggerland making a new channel to the South ( or re-utilised a former channel ). Sea-levels rose c 120’ plus to c where they are now. Until I’ve seen the latest science from York/ Newcastle Uni’s I assume North East rivers firstly discharged into the Rhine channel and fish-migrants came in from the south initially. AG

p.S. glaciers on southerly ( and probably, westerly, slopes ) melted first so inward migrations of fishes would presumably occur in those before rivers which had glaciers moving North. So Annan, Nith in Galloway would get char first then trout Well before Eden,Spey, Naver, Findhorn and Nairn which are likely examples of the 2nd type. It’s complicated since some rivers ended up flowing in the reverse direction to the glaciers which originated them. An example being an Eden tributary near Gilsland ( I forget it’s name ) where the glacier went East through the Tyne Gap. A distributary of the Tweed glacier may have entered Till and created an ice-jam leading to an outwash lake on the Milfield Plain. This later place is well researched by some leading academics.

Should you be interested, the Northern U.K. salmonid scenario at these old times is likely analogous to the situation now in Northern Labrador where salmon are found for the first time in former char-only rivers on Baffin Island - eg the Clyde river at c 70 degrees North. So this may happen in Greenland. Trout colonisation may never happen though for the reasons I mentioned earlier - non-native in NW Atlantic. Displacement of char by salmon would have severe implications for the Inuit.
 
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Auldghillie

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What does ppm mean?​

This is an abbreviation for "parts per million" and it also can be expressed as milligrams per liter (mg/L). This measurement is the mass of a chemical or contaminate per unit volume of water. Seeing ppm or mg/L on a lab report means the same thing.




Thanks, it’s all too technical for me as I’d prefer a simple percentage.
 

Auldghillie

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I worked at a water treatment works , Everything was in ppm in chemicals added to water treatment ,chlorine etc
Thanks but the problem occurs for simpletons like moi when using international data since some uses percentage and others ppt.
 

NEbody

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Salinity is usually quoted in parts per thousand (ppt or ‰). Seawater in the North East has around 35 ppt salinity. River water generally has too low a salinity for that scale to be useful.

Other substances in river water (e.g. dissolved oxygen or nitrate) are measured in parts per million. Things like trace metals are usually quoted in the parts per billion range (1 part in 1,000,000,000) and trace organic compounds in the parts per trillion range (1:1,000,000,000,000).

They’re quoted in those units to avoid silly numbers of leading or trailing zeroes. E.g. 1 ppb is 0.0000001%
 

Auldghillie

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Salinity is usually quoted in parts per thousand (ppt or ‰). Seawater in the North East has around 35 ppt salinity. River water generally has too low a salinity for that scale to be useful.

Other substances in river water (e.g. dissolved oxygen or nitrate) are measured in parts per million. Things like trace metals are usually quoted in the parts per billion range (1 part in 1,000,000,000) and trace organic compounds in the parts per trillion range (1:1,000,000,000,000).

They’re quoted in those units to avoid silly numbers of leading or trailing zeroes. E.g. 1 ppb is 0.0000001%
Thanks for that. Using your 35ppt, may I thus assume that = 3.5% salinity which is used in Baltic work I think ?
 

NEbody

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Yes, indeed, it must be e.g. pike in the Gulf of Bothnia ( very northern Baltic ). Thanks for all that.

but what about juvenile fish in that Wansbeck by-pass channel .
There isn’t a bypass channel. The river flows under the dam. When it’s seriously high (before the pre-existing flood walls in Morpeth would be overtopped), it reaches the dam at the top of the channel and backs up, flooding farmland rather than houses. It should happen very rarely.

There’s a similar but smaller scheme in the Wear catchment, at Spring Gardens on the River Gaunless
 

greenlaner2009

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I doubt it, maybe the Living North Sea Project report might help you. AG

I’ll try for you but if I recall it the project was joint between certain countries bordering on the North Sea so it’s long-winded.

The meat can be got from a piece from Dr Campbell of the RTC for the project showing sea-trout tagging results from Tweed/ Coquet I think. I’m not good with links, if you feel like it then PM an E-mail I can use, anonymous is fine.

The poster or respondent above might be correct so far as old migration routes but, for me, not the Norwegian Trench route. I say this because glaciation lifted earlier by decreasing latitude, which I assume is obvious. Also the trout would need to migrate under ice - an unlikely scenario in my eyes. There was a huge ice-cap over Scandinavia and Scotland down to c the Wash. Then the Rhine broke through Doggerland making a new channel to the South ( or re-utilised a former channel ). Sea-levels rose c 120’ plus to c where they are now. Until I’ve seen the latest science from York/ Newcastle Uni’s I assume North East rivers firstly discharged into the Rhine channel and fish-migrants came in from the south initially. AG

p.S. glaciers on southerly ( and probably, westerly, slopes ) melted first so inward migrations of fishes would presumably occur in those before rivers which had glaciers moving North. So Annan, Nith in Galloway would get char first then trout Well before Eden,Spey, Naver, Findhorn and Nairn which are likely examples of the 2nd type. It’s complicated since some rivers ended up flowing in the reverse direction to the glaciers which originated them. An example being an Eden tributary near Gilsland ( I forget it’s name ) where the glacier went East through the Tyne Gap. A distributary of the Tweed glacier may have entered Till and created an ice-jam leading to an outwash lake on the Milfield Plain. This later place is well researched by some leading academics.

Should you be interested, the Northern U.K. salmonid scenario at these old times is likely analogous to the situation now in Northern Labrador where salmon are found for the first time in former char-only rivers on Baffin Island - eg the Clyde river at c 70 degrees North. So this may happen in Greenland. Trout colonisation may never happen though for the reasons I mentioned earlier - non-native in NW Atlantic. Displacement of char by salmon would have severe implications for the Inuit.
Why would the trout have to migrate under ice when doggerland was never under the ice.
 

Auldghillie

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Good discussions...can you provide a link? I've never heard of the living north sea project, might be interesting.
Good discussions...can you provide a link? I've never heard of the living north sea project, might be interesting.

enetic stock identification of sea trout (Salmo trutta L.) along the British North Sea Coast shows prevalent long-distance migration​

Dorte Bekkevold, Adam Piper, Ronald Campbell, Philip Rippon, Ros M Wright, Charles Crundwell, Klaus Wysujack, Jamie R Stevens, R Andrew King, Kim Aarestrup ... Show more
Author Notes

This may be old research used as a base for the LNSP but I can’t open the paper. I may have the working papers but clearly I’d have to check.
 

Auldghillie

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Why would the trout have to migrate under ice when doggerland was never under the ice.
I think you need to read my post again as that is not what I state. It may also help you to read up on Greenland glaciation at today’s date. There is a time interval when the sea becomes ice free in summer but rivers are just freezing-cold torrents of ice melt and sediment in which it is impossible for eggs to survive even if fish like char could wander in from elsewhere. This appears why there is only one salmon river in Greenland. Lakes appear necessary to filter-out sediment and act as a winter refuge for Parr.

At shallow depths at sea, glaciers and even sea-ice can ground. Secondly, trout, during coldest eras would have needed to migrate into rivers completely locked Up with ice. Clearly impossible so, for me, a migration from the south is more likely. Though I’d be interested in how a Baltic route could work - that would seem to be only possible much later.

Best do your own research and rely on that as it’s a complicated and dynamic subject. AG
 
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greenlaner2009

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I think you need to read my post again as that is not what I state. It may also help you to read up on Greenland glaciation at today’s date. There is a time interval when the sea becomes ice free in summer but rivers are just freezing-cold torrents of ice melt and sediment in which it is impossible for eggs to survive even if fish like char could wander in from elsewhere. This appears why there is only one salmon river in Greenland. Lakes appear necessary to filter-out sediment and act as a winter refuge for Parr.

At shallow depths at sea, glaciers and even sea-ice can ground. Secondly, trout, during coldest eras would need to migrate into rivers completely locked Up with ice.

Best do your own research and rely on that as it’s a complicated and dynamic subject. AG
Why would trout have to migrate to rivers completely locked up with ice, what is the river wear now flowed across doggerland and was never locked up with ice.
 
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