Tommore Burn project: stocking monitoring

Readers of the blog and followers of the Spey will be aware that the Tommore Burn has been stocked with 0+ salmon for a number of years and since 2013 all stocked fish have been fin-clipped. We surveyed two of the regular monitoring sites in July one very still and midge infested evening along with some of the Spey ghilies. The remaining two sites we left until the last day of the 2015 electrofishing programme, mainly so that we would be able to assess how well the 2015 stocked fish had done.

The four electrofishing sites cover the lower, middle and upper reaches of the burn, straddling a range of habitat zones from mixed broadleaf to moorland fringe in the upper site.

The results from the 2015 monitoring with 2014 for comparision, are shown below.

Tommore burn electrofishing results 2015 and 2014.

Tommore burn electrofishing results 2015 and 2014. There were no salmon fry in 2014 as all the monitoring was done prior to that years stocking. It can been seen that good densities of salmon fry had been established in both sites in 2015. Overall the mean salmon parr densities were similar in both years, 12.0/100m2 in 2014 compared to 12.9/10m2 in 2015. We have no  late season surveys from 2014 with which to compare the 2015 results. Trout fry and parr densities were also higher in 2015 than in 2014.

The lower Tommore Burn stocking monitoring site.

The lower Tommore Burn stocking monitoring site.

Although we are only dealing with two sites and small numbers of fish it was interesting to note that the mean size of the stocked fry in the lower site was 55.4mm whereas it was 58.5mm in the upper site.

Teo fin-clipped salmon fryb from the upper site. These fry were sampled one month after stocking. Whilst they are lean the tail fins are very healthy looking

Two fin-clipped salmon fry from the upper site. These fry were sampled one month after stocking. Whilst they are lean the tail fins looked perfect.

We are building up a good set of data from the Tommore Burn now; electrofishing and smolt trapping, both of which we will continue in future years.

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Tropical storm Bertha aftermath: juvenile stock survey and mainstem stocking monitoring

Trying to assess the impact of extreme spates on our juvenile stocks is a long held ambition and something I promised to do at the Spey Fshery Board AGM two years ago. Big Bertha provided the ideal oportunity with pre event electrofishing survey data available and the low water in September providing ideal conditions for repeat surveys.

The Spey up in amongst the trees on the 11th Aug 2014

The Spey up in the trees on the 11th Aug 2014

For the monitoring strategy we decided to replicate some of the timed surveys in the Spey mainstem and River Fiddich. Eleven timed sites were repeated on the Spey and four in the lower Fiddich. The results were interesting with a statistically significant reduction in the fry counts but an increase (although not significant) in the parr counts. The three Spey mainstem sites with the largest reductions in fry counts were all in areas where the riverbed was liable to become mobilised during the peak of the spate. There was less of a change in the pre and post spate counts in more stable parts of the river.

We found evidence of downstream movement of juvenile fish, something that was particularly evident in the Fiddich where the thermal uplift from the distillery cooling water has unique effects.

The salmon fry numbers overall in the Spey survey sites after the spate were close to the average for the whole Spey in 2014 summer surveys. In the Fiddich the decline was greater although from a higher base level. The study raised as many questons as it answered. For example how many fry would we normally expect to find in September compared to the usual monitoring time of July? I would probably expect to find similar numbers in September as the bulk of the overwinter mortality probably occurs in the autumn onwards.

The perceived wisdom is that although fry numbers are lower now than they would have been if there had been no damaging spate the survival of those remaining should be better due to less competition. We hope that this will be the case although we will have to wait until next years surveys to establish that. The 2015 smolt production will almost certainly be impacted by the big spate and the subsequent fish kill but no doubt nature has its ways of compensating.

Following the Bertha spate a decison was made to stock the 50,000 lower Spey origin hatchery fish back into the lower mainstem rather than into lower river tributaries. We were able to monitor the impacts of this stocking as the stocked fish were adipose fin clipped by the Spey ghillies. The fin clipping allowed us to successfully identify the stocked fish so that their contribution could be assessed.

The results from the stocking monitoring and the post spate monitoring can be read by clicking here.

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Stocking monitoring completed!

So after four days of electrofishing the areas we stocked, we have now completed the stocking monitoring for this year.

On Tuesday, we electrofished the Burn of Mackalea and the Rothes Burn. The sites on the Rothes burn were new ones, with one just above the impassable distillery weir, and the other further upstream beyond the golf course. At the weir site, there were only two salmon with good numbers of trout fry, and trout aged both 1+ and 2+. At the site further up, there was just one salmon, and several trout probably one or two years old. On the Mackalea burn, the lower site had 1 salmon in comparison to 2 last year, with trout numbers lower too. The upper site also saw a reduction in the numbers of salmon which was disappointing.

On Wednesday, we left the car behind and set off to do the Burn of Brown sites, which require a fair bit of walking. This burn is not accessible to salmon due to a fairly impressive gorge like waterfall, which is popular with gorge walkers.

The gorge like waterfall on the Burn of Brown

The gorge like waterfall on the Burn of Brown

The first site was very long, and doing it three times was fairly hard going! This site had almost exactly the same number of salmon as last year which is positive and shows it is consistently a good place for them to mature. The numbers of trout had decreased though, perhaps the salmon are out-competing them.

First site on the flood plain of the Burn of Brown. The sun shone the whole day!

First site on the flood plain of the Burn of Brown. The sun shone the whole day!

The second site showed almost the same number of salmon and an increase in trout which was a good result! The final site also showed fairly consistent numbers of salmon with less trout.

Thursday saw us at the Cally Burn, not far from the office. Here unfortunately we did not find any salmon. The rest of the day was spent up the Batten Burn, near Carrbridge, where the lower site showed a very slight reduction in salmon, and the upper site showed lower than last year too. Although quite a few of the sites seemed to show a decline, the salmon that were present were in very good condition. I will have to look more into the sizes of fish caught to see how much they differ in size in comparison to last year. A few of the sites were also fished in very challenging conditions, efficiency of the electrofishing can play a role in the numbers you catch.

Today we started the mainstem sites on a very hot day! Waders are not the best hot weather gear. We started at the Brae Water beats and will steadily work our way up. This will be the third year of using the fry index method of surveying, so it will be useful to hopefully see a pattern building up.

Beautiful weather to start off the mainstem surveys.

Beautiful weather to start off the mainstem surveys.

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