Spey mainstem sampling: a quick and almost complete summary

With 59 sites surveyed (the last 2 will be surveyed tomorrow) the picture from the salmon fry index survey on the Spey mainstem is almost complete.

Last year the mainstem monitoring system was revised and replicated this year. Two new sites were introduced but the results from these have been omitted from the comparison below.

Year         Mean number salmon fry per minute    Mean number salmon parr per minute*

2012                             13.6                                                          1.4

2013                             21.2                                                          4.1

* Note all results now expressed as number per minute found during the three minute timed surveys.

Salmon fry numbers have increased by 56% whilst the salmon parr numbers have increased 3 fold. The low water that persisted throughout the mainstem survey would no doubt have had an influence but that factor alone cannot explain the increase in numbers recorded. Whilst the river was low we are still talking about a channel that was 50m wide whereas in normal low water flows it would be 55m wide. Some of the survey sites will be more affected by low water conditions than others but we will provide an analysis of that when the final electrofishing report is published.

A complete river fry index survey should highlight areas where fry numbers are high and low. In this case the damaging impact of Spey Dam on the upper Spey salmon population is all too apparent but localised areas in the middle river may also be naturally less good for fry production. More detailed examination of the results is required to establish this.

This survey is designed to be a salmon fry index survey and in sites which consisted only of fry habitat then we found few parr. However not all of the sites are exclusively fry habitat and where parr habitat was present we generally found parr in good numbers. The impact of the site at Aberlour, where over 100 parr were recorded, on  the average number per site is significant but even if it is excluded the mean parr count per minute was over 3.4 in comparison to 1.4  last year.  This represents highest mean parr count reported from the mainstem since monitoring commenced in 2002. However the new monitoring protocol is targeted at run/riffle habitat whereas prior to 2012 a variety of habitat types were surveyed each year. Some detailed analysis on an individual site basis is required to provide a true comparison with our long term dataset.

However it is positive and encouraging and thankfully it matches what many experienced rods and gillies are observing and reporting; I would be very concerned if our results differed widely from that noted by open minded and observant river watchers.

There are 2 comments for this article
  1. Stuart Brabbs at 11:13 pm

    Good results there Brian. We have found 2013 to be up on previous years too and on all our rivers here in Ayrshire. This following a winter where salmon were not thought to be too numerous on the redds. It will be interesting to see what other rivers biologists are reporting.

    • Brian Shaw Author at 6:37 pm

      I have been watching your results on the blog Stuart, good to see great fry numbers in Ayrshire as well. I see the Tweed bologists are reporting the same on their blog.
      ATB
      Brian

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