River Calder stocking monitoring

The River Calder is generally taken to mean “hard water” i.e. a bouldery stream, very apt for this mobile river which has its headwaters in the high grounds of the Monadhlaiths before joining the Spey at Newtonmore.

The high energy River Calder. The Calder is capable of supporting good fish densities, but only if conditions are benign. The river bed mobilises readily in high flows, redds tend to be washed out in these conditions.

Our monitoring in the Calder had identified that is was a part of the catchment where juvenile stocks currently appeared to be well below what had previously been found there. At the 2017 Spey stocking sub-committee meeting it was agreed that an attempt would be made to try and increase the juvenile population in the River Calder.

River Calder, Site C2 at Dalnashallag Bothy. Most of the surveys up to 2003 had recorded salmon parr densities in the good or excellent categories, whereas since then they had been poor or very poor.

Broodstock were collected from the Spey mainstem, in the Newtonmore area, in Oct 2017 and the eggs held in the hatchery at Sandbank. Vehicle access to the upper reaches of the Calder is poor. There is a riverside estate road as far as the middle reaches, but the only access to the upper reaches is via the Cluny Estate track. For this reason it was decided to stock the upper reaches with eyed ova. Eyed ova are easy to transport; they can be carried a long way in a bucket. Accordingly in early March Steve and Brian collected 18,500 eyed ova from the hatchery and headed to the upper Calder.

This was shortly after the “Beast from the East” but as the eggs were beginning to hatch they had to be planted out or the window for this type of stocking would have been missed. After a snowy drive we arrived at the river, but where was it? Most of the river was covered in snow and ice but thankfully there were enough suitable open areas to allow us to create 14 artificial redds where the eggs were planted out.

Steve pouring eggs into an artificial redd in the upper Calder.

Preparing a redd in a suitable area of open water

The eggs, approximately 1500 per redd, were poured down a pipe which was dug into an area of prepared gravel.

A completed artificial redd in a snow bound River Calder, March 2018

Locations of the eyed ova planting in the upper Calder March 2018

Prior to the egg planting a day was spent redd count in the Calder in Nov 2017. In the upper 5km 15 redds were counted, a low density in comparison with most other parts of the catchment, but it showed that some fish were spawning in the Calder.

Redd counting in the upper Calder November 2017.

There were two redds in this excellent spawning gravel in an “S” bend in the Calder

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The remainder of that upper Spey stock were held in the hatchery for planting out in September this year, at the more usual 0+ parr stage.

One of the key roles of electrofishing is to monitor activities such as stocking. Earlier this week Steve, Jim and Brian spent a day and a half completing a range of electrofishing surveys in the Calder. These surveys included a repeat of the 2017 timed surveys, a semi-quantitative (area based) survey at the long term C2 site (see above), and a new semi-quantitative survey for the new National survey (https://www.gov.scot/Topics/marine/Salmon-Trout-Coarse/Freshwater/Monitoring/ElectrofishingProgramme ).

The results from the 2017/2018 timed surveys in the River Calder. The Calder is only a short river so only a few sites are required. In this type of survey the results are expressed as fish caught per minute. It can be seen that at all sites the fry counts were higher this year than in 2017. Only site TC18 was located within the stocked area, TC10 being located 1.3km downstream of the furthest downstream eyed ova site. Given the absence of spates this summer it is likely that the fry would not have spread that far downstream since emergence from the gravel in Mid May.

TC18, timed site in the upper Calder. We caught 33 fry in the three minute survey here; the count would have been much higher if we had been there the day before as the Calder had risen quite a lot on the back of the overnight rain.

Steve after returning the catch at site TC10, where 69 salmon fry were caught, almost three times higher than in 2017.

There was no timed site close to the upper limit of the eyed ova stocking but we resurveyed site C2 again. This was a quantitative site so the results are per 100m2.

Site C2 with the 2018 survey results. The density of salmon fry was improved, in comparison with recent years, parr densities remain low.

It appears from the electrofishing that salmon fry, and parr counts/densities, were much improved in the Calder this year. The timed surveys suggest that the stocking with eyed ova resulted in improved fry densities in the upper reaches, although it is not possible to be certain without further studies such as genetic analysis.

Fry counts were very low in site TC05, which is located at the top of the steep section in the glen, where salmon spawning opportunities are limited or non-existent.

The Calder lives up to its name in this section. Great parr habitat but there is virtually no spawning habitat in the vicinity due to the bouldery nature of the river. I would suggest that the remaining parr in the hatchery should be stocked into this section of the Calder.

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Salmon redds in the lower Calder, downstream of the A86 road, in Nov 2017. There were a high density of redds in this part of the river but the fry count was only 110. 110 fry in a three minute survey is good but considering the density of redds I was expecting higher. The fry size here was the second smallest out of the five timed surveys completed in the Calder, even thought it was the lowest altitude. This will be due to competition, too many mouths to feed in a relatively low productivity tributary. This could be a good site to try fry relocation – catching fry soon after emergence and relocating further upstream where fry counts are lower.

To summarise
– there were improved fry, and parr counts throughout the Calder in 2018, some of will be due to the eyed ova stocking
– consistent low fry counts were identified in the steep section through the glen, the remainder of the fry in the hatchery could be stocked here
– the lower reaches could be a suitable site for a fry translocation trial
– the Calder is a high energy tributary, the river bed is unstable and mobile under very high flow conditions.
– flows over the last year have been relatively benign, a necessity for decent juvenile densities in the Calder.

Authored by: Brian Shaw

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