Stocking Corrie and Tommore Burns

On the 29th June the Tommore and Corrie Burns were stocked with salmon fed fry. The decision was taken to stock these two burns earlier than the release stage planned for the remainder of the hatchery fry as it will enable the Foundation staff to revisit the stocked sites in August to assess survival and growth of the stocked fish.

Both of these burns were stocked with fry from broodstock sourced at the nearest possible point, i.e. the Fiddich in the case of the Corrie Burn and the Avon for the Tommore. Both burns are inaccessible to migratory salmonids due to obstacles in the lower reaches; namely a obsolete weir on the Corrie and a road culvert on the Tommore. If salmon fry are found during the electrofishing surveys then we can assume they are from the stocking.

A sample of fry destined for both burns were measured. The size distribution is shown in the graph below.

Size distribution of Corrie and Tommore stocked salmon fry

The average size of the fry in both sites were almost identical at 34.75mm, although it can be seen that the Fiddich fry were more uniform in size. The estimated stocking density was 2/m2 although there is considerable margin for error in the actual density at any one point.

The fry were bagged in double large plastic bags filled with oxygen for the short journey from the hatchery to the burns.

Preparing the oxygenated bags prior to the release of the fry

The fry were stocked at a low density in suitable habitat (shallow, fast flowing) using buckets and hand nets.

Bucket of salmon fry ready for stocking

Planting out fry into suitable habitat

Habitat quality in both the Corrie and Tommore Burns was excellent although they were quite different in character. The Corrie drains farmland and richer geology so growth rates are expected to be higher.

Good mixed habitat in the Corrie Burn

The Tommore Burn drains moorland and the water often carries a dark peat  stain.

Typical excellent habitat in the upper Tommore Burn

These fry were quite small when they were stocked out so it will be interesting to see how their growth compares with the remainder of that stock in the hatchery. I have a pint wager on with the hatchery manager that the stocked fry will be larger than the hatchery fish when we carry out the electrofishing surveys in August. The problem with that is that the growth rate of the stocked fish is now totally reliant on their adaption to the wild and habitat and environmental conditions, whereas I hear the hatchery fish are now on double rations!

 

There are 3 comments for this article
  1. Brian Shaw Author at 3:48 pm

    Doug,

    Our hatchery manager, Jimmy Woods tells me that the salmon started hatching on the 21st Feb and was largely over by the 28th Feb. The hatchery salmon are now about 55mm. We will monitoring the stocked burns next week after which I’ll report with the esults, sizes etc.

    Brian

  2. Doug Wallace at 7:28 am

    Hello,
    For comparison with our own fry. What was the hatch date of your Salmon fry?
    Our (Ugie) Salmon fry started to hatch on 29/1/2012, average size now just under 50mm.
    Our Sea Trout fry started to hatch on 18/1 2012 and are now about 80mm. The Sea Trout have been doing a lot better for some reason, very few losses compared to the Salmon fry. Our Salmon fry are still on 01 feed and the Sea Trout fry are coming off 02 and starting with the smallest of the pellets.

    • Brian Shaw Author at 7:52 am

      Hi Doug, thanks for the comment. I’ll need to check with the hatchery manager for the hatch date. The Spey hatchery is located at 250m (820′) altitude so water temperatures will be cool in comparison to the Ugie I would imagine, especially this summer. The size of the Spey hatchery fry will be similar to the wild fish in the same area of the river. The choice of the hatchery location predates my time on the Spey by many years but I assume it was a deliberate choice to ensure that growth rates were not too advanced.
      Your sea trout fry are very advanced, it would be September at least before wild trout fry were averaging that size, and I’m not talking about the Spey catchment, rather more southerly rivers.
      I’ll post the size of the stocked salmon fry from these burns when we complete our monitoring surveys in August.

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