Dirty water clearing & some fishy findings

Duncan Ferguson sent me a photo from the upper Spey just below Spey Dam yesterday and it looks as if the river is clearing at last. Significant rain in the west of the catchment has helped greatly. Duncan had hiked/biked to the upper reaches of the Markie and found that the landslip had occurred at the bottom of a practically inaccessible gorge in one of the tributaries. The sides of the burn looked as if they had been well scoured in the deluge.

When we were up in the area last week we repeated the timed survey site just downstream from Spey Dam as there was concern that the persistent dirty water would be having an impact on the fish population. The results were interesting….

For a start we found many more fish than we did during the initital survey in late July (pre dirty water); actually we found over three times as many salmon fry, along with a good few parr. Some of the parr were very well conditioned  (see below) but the average size of the salmon fry had decreased compared to the previous survey.

Very well conditioned salmon parr from site just below Spey Dam

The drop in average size suggest the fry may have been struggling to feed but maybe the size dropped for another reason? Fry from the glide and pool habitat nearby might have moved into the riffle during the dirty water episode? We checked the invertebrates and there was the usual selection of mayflies, stoneflies etc but there were also a lot of small midge larvae. Some species can react very quickly when conditions are right and the silty conditions are likely to suit midge larvae. They would be a good food source for fry and parr.

Dirty water at the Blargie site, upper Spey.

Based on the evidence from this one site there doesn’t appear to be any real concern about the salmon population in the river affected by the dirty water. Anyway hopefully it will soon have cleared completely.

Below is a picture of a 35cm trout we found in one of the burns above Spey Dam. It came out of the blue in some rough water during the electrofishing survey. A tiddler compared to some trout in the Spey but still a cracking wild hen brownie for that wee burn.

Big trout from the Allt Feith a’ Mhoraire

 

 

 

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