Author Topic: Forestry Impacts On Trout  (Read 95 times)

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Offline admin

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Forestry Impacts On Trout
« on: April 11, 2021, 10:00:45 PM »
This is interesting

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Offline Laxdale

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Re: Forestry Impacts On Trout
« Reply #1 on: April 12, 2021, 10:18:32 AM »
Stuart is a good lad. Likes his ferox fishing.
I wish he had shown the outlet of the loch to see what was causing the inlet to be acting like a silt trap!

Online Bobfly

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Re: Forestry Impacts On Trout
« Reply #2 on: April 12, 2021, 02:44:28 PM »
I found that video rather hard to follow as to what they were intending to show. The FC would readily give them a map of the streamcourse showing open areas, felled areas, areas beside the stream due to be cleared back and so on. Seeing that would help set out what their project is about. The FC and others have been clearing back and planting broadleaved groups, or not replanting as close as before, for many years. Work by the Galloway Fisheries staff has been going on for 40 years. The introductory scenes were of a section of very flat peat ground leading into a loch which is just where the sediment would drop out, but the trout for spawning would surely move above there heading for coarser gravel and stones.
The gist of the seeding in seems to be that the trout were either not going into that stream to spawn or that the spawning success was very low. Most of the Galloway granite areas had a naturally low Ph and it was thought that the conifer planting had exacerbated that but diatom samples taken from sediments in lochs above the tree line showed Ph had fallen back since the 1800s and predated the plantings. The conclusion with low spawning success was put down to the filtering effect of the conifer canopy which harvested acidic particles on the needles during lighter rain and mists that fell on the canopy and evaporated off leaving a gradually accumulating residue. When there was a heavier fall that then caused an acid flush of lower Ph which, if it was low enough and at the wrong time in the ova development, stopped egg growth and knocked back that years recruitment. Ph below a certain point stops some enzyme or something or other.
What they are doing here seems to be to have a small hatchery batch that can be introduced after that crucial growth stage and so would then be unaffected.
Maybe something along those lines ....... !!
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