Smolt traps update

I could summarise the situation very quickly with a few words – not much happening. Water levels and temperatures are still very low so it is little surprise that few smolts have been trapped. At the end of March 2013 we had trapped 12 salmon smolts in the Tromie trap with 7 in the Truim.  The number of salmon smolts captured to the end of March over the last few years are shown in the table below.

Tromie and Truim smolts captured to the end of March 2009 to 2013

Tromie and Truim salmon smolts captured to the end of March 2013 to 2009

It can be seen that there is great variability in the extent of the early spring smolt run. Studies such as this are of most value when part of a time series of results, the factors driving smolt production and timing can then be understood better. The early smolt run in 2013 has been small but that should be no surprise, this is one of the latest springs in recent years. However the results to date in 2013 are not too dissimilar to those recorded in 2011/10 although the efficiency of trap operation in those years has to be taken into account.

This picture taken recently by Duncan Ferguson SFB Operations Manager illustrates why the smolt run is likely to be late this year.

A snowy Glen Einich. The Am Beanaidh, a tributary of the Druie flows along the bottom of the valley pictured.

A snowy Glen Einich. The Am Beanaidh, a tributary of the Druie “flows” along the bottom of the valley pictured.

The snow is currently thawing very slowly with little impact on water levels although that could change quickly.

There are 6 comments for this article
  1. Chris at 8:34 am

    In Canada, when we wanted to collect eggs from walleye, we waited until the spring peepers were peeping and we never missed a run. Saved a lot of waiting around checking water temperatures.

  2. Chris at 3:59 pm

    HI Brian: Do you do these surveys the same date each year or do you base them on cumulative mean daily temp?

    • Brian Shaw Author at 9:01 pm

      Hi Chris, We generally put the traps in at the beginning of March and remove them near the end of May. Experience has shown that the smolt run always occurs during this period although the peak of the run can vary considerably; this year will be different to the others in that respect I’m sure.

      Henry Morrice, the late and great river Superintendent for the Kyle of Sutherland Fishery board said that the smolts ran when the birch buds opened. I must check if this applies to the Spey as well.


  3. Brian Doran at 10:20 am


    In your note commenting on the Smolt run you cite the current cold weather as the reason the Smolt run is likely to be late this year.

    By way of comparison, do you have the average temperature at the end of March for the years shown in your table?

    Kindest regards


    • Brian Shaw Author at 2:06 pm

      Hi Brian,

      In last years smolt traps reports the mean daily temperature at Aviemore was used for comparison with previous years trapping. The website used hasn’t updated the March totals yet although Jan and Feb are available see . The cumulative mean daily temperature to the end of Feb 2013 was 110degree days, only 2010 was colder at the same point during the last five years. March 2013 will I’m sure be considerably colder than the same month in 2010 but the cumulative temperature for the year to date is unlikely to be lower than the winter of 2010. It would be good if you could use something as readily available as the mean daily temperature to predict the main smolt run; that would be useful in the upper Spey where most of the flow is controlled by the hydro companies.

      Steve and Jim, who operating the traps on a daily basis say that they can’t remember such a sustained period of cold and low flows during the smolt trapping. The smolts will run eventually, they always come, but the colder winter/spring is likely to result in reduced output this year. I just hope that we get a good trapping season again so that quantify the run well.

      Thanks for your interest and enqury, I will update the mean March temperatures when available.

      Best regards


      • Brian Shaw Author at 7:12 pm

        Hi Brian,

        The website I used last year now shows the mean temperature in March at Aviemore to be 0.6 degrees C giving a cumulative for the month of about 19degree days. That was by far the lowest in March during the last five years. Unfortunately the dramatic change in the weather at the weekend has wreaked havoc on the smolt trapping. Both rivers rose to very high levels on Sunday morning. Steve and Jim were able to lift the drum on the Tromie trap, so it will be okay although obviously the trap is not set so no fish will be caught. The Truim trap is still inundated with water and is impossible to reach due to the spate conditions. Surprisingly this morning the level had only dropped 8cm in the last 24 hours, there must have been more overnight rain. On Saturday 28 smolts were captured in one of the traps, the first decent day so it is a great pity the big spate arrived when it did. The impact on the efficiency of this seasons trapping may be significant but at least the smolts ready to migrate had the benefit of a truly big upper Spey spate.


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