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!

 

Leave a Reply

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.