Following a site visit with the SEPA restoration project manager at the Corrie Burn weir we went for a look at the weirs and fish passes on the Dullan Water in Dufftown. The Dullan is a noted sea trout burn and signs of their spawning activities were soon evident. Wearing the polaroids the big redds were very easy to spot. Others were more subtle and not all were in the classic tail of pools location. The photo below shows a small redd in-between small boulders. Sea trout seem to me to be much more skillful redd builders than the salmon. They often gather the gravel from all round to create a redd where there doesn’t appear to be enough to cover the eggs.
There were a few dead sea trout lying about as well, I saw three of about 3lb in a few hundred metres. None had any signs of predator damage so I assume they must have succumbed to the strains of spawning. Many sea trout are multiple spawners but obviously for some this year was their last year. Here are photos of a couple sea trout kelts covered in fungus.
There were plenty redds above the upper weir as well as upstream of the Giants Chair. Above the Giants Chair I found a great example showing why large woody debris (LWD) is so beloved by fishery biologists. Here a tree had fallen over into the flow and downstream a plume of spawning grade gravel had accumulated. The Dullan in this area was generally straight and the bed was pretty well armoured with cobbles, providing few spawning sites. However in the lee of the fallen tree there were four trout redds. It may be high risk spawning in this location; after all if the tree moves so will the gravel but look at the upside. With the lack of other spawning sites in the area the fry from these redds could find themselves in good habitat with little competition from other fry. I’m not sure how a sea trout chooses its spawning site but this apparently high risk spawning strategy obviously works or they wouldn’t do it!
The lack of light, and a meeting with the chairman back in the office (although he was late) meant I had to turn back. So that was another very interesting walk. Incidently we hope to remove the Corrie Burn weir next year; that will be another great sea trout burn once its opened up.