A Spey urban burn

The redd count on the Rothes Burn provided some interesting info. The Rothes Burn has many of the typical problems of urban burns: japanese knotweed all along the banks, litter, engineering (gabions, pipes etc) and obstructions. Despite this there were no shortage of redds, although if we had been there a week ago the impression may have been different. We started at the confluence with the Spey but it was a couple hundred yards before the first salmon redds appeared, although we started seeing redds as soon as we came across the first good gravel.

Most of the redds were smallish but the remains of a predated cock grilse supported our thoughts they were salmon (two otter kills in two days – success!) The redds were coming thick and fast now as we entered the suburbs of Rothes. We got chatting to one resident who’s garden backed onto the burn. He said that on Wed/Thu night, during a small rise in the level, there were a lot of fish spawning in the darkness, the first he had noticed this year. He and his neighbour had both heard them splashing at about 10pm (okay not quite on the same scale as Charles MacLaren’s claim that he was kept awake by the sea trout spawning in the Ewe, but that’ll do for me). We had thought that most of the redds were of similar vintage, i.e. freshish. The residents report and what we had observed suggest that most of the spawning activity occurred recently.

The photo below shows the location of a couple redds in the stretch where the banks were reinforced by gabions.

Two redds by the gabion baskets

Just below the main road there is a small weir and apron but there is a fish pass. We did find a few redds upsteam but there was a distinct reduction in the density, although the gradient of the burn increased.  There are other issues like abstraction in this part of the burn but that’s for another day.

Rothes Burn weir and fish pass

We recorded 34 salmon redds and 5 sea trout redds in the 1.4km from the Spey to the main road bridge with a couple more upsteam, a good number. No doubt these fish were lying in the Spey waiting for a rise in levels to allow them in. If we had been there a week ago we may have recorded a lot less.  There lies one of the problems of redd counting – timing. Repeat visits to any site are worthwhile but we only have limited resources and time available. That was another interesting day enhanced greatly by the intelligence from the observant, and sound of hearing, resident.

We did have a look in the main river in the upper Brae Water beats later where we saw a few redds, that was all, but it is normally into December before the fish start spawning properly down there, hopefully more redds will appear in the next couple weeks.

There are 2 comments for this article
  1. Gordon Mackenzie at 9:48 am

    In order to try and get a better idea of whether 34 redds is a good count or not, what percentage of the good spawning gravel was used in the burn by salmon?

    • Brian Shaw Author at 10:11 am

      Hi Gordon, Our redd archive redd count data is a bit patchy for the Rothes Burn but there are data from two previous counts on the Rothes Burn, both back in the 90s. One was zero, the other 29. So using these figures this years count is twice the average! Well I’m sure that’s not the case but apart from one pool tail where I thought there should have been a spawning fish there were redds in every other suitable location, and in others that didn’t look like classic spawning sites. The average width of the Rothes Burn is about 5m in the lower section, wetted area about 7000m2. 34 redd should give an egg deposition of about 170,000, or 24/m2. Thats good.
      Brian

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