Spawning of salmon and trout on the Dee is now in full swing. Each year, the staff of the Dee DSFB survey for spawning fish and their product – the ‘redd’, or nest, where the fishes’ eggs are laid – to assess spawner abundance and variability. Spawning started in the upper catchment in the last week of October and peak spawning has now happened; it's great news that the surveys have found very high numbers of spawning fish – by all accounts, the best in recent years. This gives us some optimism for our spring salmon stock, which predominate in the upper catchment and have in previous decades suffered a substantial decline.
Opposite is a short (18 sec) video clip of the salmon on the spawning grounds, near Aboyne, at the weekend. You can see three males, all jostling for the best spawning gravels. The strongest male usually prevails and chases off his rivals. The males often spend some time on the spawning grounds – perhaps weeks – and during this time they are continually fighting with other males for the best spawning gravels, as then they will have the most females visit their area. After days or weeks of fighting, even the strongest males will end up wounded, making them very unlikely to survive long-term after spawning.
Spawning will occur throughout the river where there is suitable substrate for the fish to dig their ‘redds’, so they can bury their eggs under the surface of the stream bed. In low flow conditions, if you take a walk along the riverbank you should notice a fair bit of commotion in the shallow water, as fish jostle for space on the best spawning grounds. It’s quite easy to see, but much harder to film! The video clip shows how shallow the water is that the fish are spawning in – so in flows, their backs are often out of the water and you have a good chance of seeing them.
Here's a second clip – it’s a bit longer (1 min) but shows what a hive of activity the spawning grounds are, at the right time. You can see several areas where males are chasing one another. In this stretch of river, it appears that peak spawning has already occurred and it is now mostly the males that remain, waiting to sweep any late-arriving females off their feet, so to speak.