Smolt trap updates

This post provides an update on catches in the Tommore and Avon smolt traps as of this morning.

River levels increased in both the Tommore and the Avon over the weekend, mainly due to the thawing of the snow which fell on Friday and Saturday. On the way back down from Glenlivet on Saturday afternoon the temperature in our car read 1.50C, it was bitterly cold in some of the heavy snow showers although a lot milder on Sunday and even more so today with half a gale blowing from the west. All the recent snow in the Tommore hills has gone although there is still plenty lying in the Cairngorms above 3000′ or so which should keep the Avon at a moderate level.

Recent catches in the Tommore have been slow with only one salmon smolt caught over the weekend, along with a few parr. Total catches to date are: salmon smolts/presmolts = 310, salmon parr = 70, trout = 89. The average temperature recorded in the Tommore so far this year has been 4.6oC, slightly lower than the 4.72oC recorded during the same period in 2015. The burn level has been higher on average this year (17.8cm compared to 14.5cm in 2015). In summary there has been more water but colder so far, although temperatures should rise this week.

Tommore Burn dily salmon smolt catches to date related to water level

Tommore Burn daily salmon smolt catches to date related to water level.

 

Tommore Burn salmon smolt cumulative total compared to 2015.

Tommore Burn salmon smolt running total compared to 2015.

In the Avon smolt traps the catches have increased with the salmon smolt catch today (155) being the highest so far this year. To date the salmon smolt catch this year is 536 (477 same date last year). Trout catches in the Avon (197 so far) are well ahead of that recorded by the same date in 2015 (85).  Our river level gauge in the Avon is reinstalled each year so we have no relative measure of river levels over the years (we will obtain flow data from SEPA for the Delnashaugh gauging station in due course) but we do know that the temperatures have been similar, although marginally colder this year (5.1oC average compared to 5.2).

River Avon smolt traps daily salmon smolt catch related to river level.

River Avon smolt traps daily salmon smolt catch related to river level.

The major difference between the Tommore and the Avon traps is that the Tommore is a total capture trap i.e. designed to catch everything coming downstream, whilst the Avon traps only sample a small proportion of the total run. To address this we run mark/recapture trials in the Avon with three completed so far this year. From these three trials the recapture rate so far this year has been 3.4% compared to 11.9% at this stage last year. The lower recapture rates are almost certainly a reflection of the higher river levels this year in the Avon. What this means is that we are only catching approximately one in thirty of the smolts going downstream at present. A further trial was initiated this morning with 154 salmon  marked and released back upstream so we anticipate a few recaptures tomorrow.

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Smolt trap update

What a difference a week makes; this time last week the Avon smolt trap catch was ahead of the same date last year but one week on the running total is now well behind. In the six day period up to 26th April 2015 we caught over 2000 smolts in the Avon traps compared to 93 in the same period this year. Each year is different of course with snow featuring more than sun in the forecast on Speyside over the last couple weeks. The average river temp over that six day period this year was 5.3oC compared to 8.8oC last year. River levels have dropped over the course of the week whereas last year there was a small rise midweek. Still we are nearer the start of the normal smolt migration period than the end so there is time yet but it would be good to see the run increasing soon.

River Avon smolt traps daily salmon catch related to river height

River Avon smolt traps daily salmon catch related to river height.

River

River Avon smolt traps daily catch related to river temperature.

On the Tommore Burn the catch has been equally slow with one smolt trapped over the course of the last week. The temperature was only 3.1oC this morning but the snow over the last few days should produce a rise in water levels when the thaw arrives.

Tommore smolt trap running total 2015/2016

Tommore smolt trap running total 2015/2016

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Smolt trap update

Quick update on the Tommore and Avon traps

Tommore

Catches have declined since the big catch last Tuesday along with water levels.

Tommore Burn trap daily catch related to river level

Tommore Burn trap daily catch related to river level.The total presmolt/smolt catch to date is 307, well ahead of last year although the trap was deployed much earlier this year. On a like for like basis the catch this year is lower than in 2015 although we will never know if we missed a similar early run last year.

One interesting feature is the capture of 59 fin-clipped one year old parr (only 2 during the whole deployment in 2015). These are generally between 55 to 70mm and will not smolt this year. The trout catch in the Tommore is also well ahead of 2015; 82 trout have been caught so far compared to 7 at the same date last year (virtually none during the earlier deployment period this year). The same high trout catch has been recorded in the Avon trap and the Deveron guys report similar in the Fiddich and Deveron traps.

Tommore trap running total salmon presmolt/smolt 2015/16

2015/16 Tommore trap running total salmon presmolt/smolt

Avon

Catches have been steady over the last week. Two recapture trials have been completed with low recapture rates between 2.5 to 10%. The running total for salmon presmolt/smolt so far is 255 compared to 275 at the same date in 2015. The trout catch is much higher for the same date; 136 trout have been caught in the traps compared to 50 last year. Something different is occurring with the trout this year.

We are inspecting all the salmon careful for fin-clipped fish and on the 10th April four fin-clipped one year old parr were caught in the Avon traps. So far only 59 fin-clipped 1+ parr have been caught in the Tommore trap, including 11 on the 9th. Of course parr are likely to have been migrating out of the Tommore all winter so will not know if these were recent emigrants or fish which have been sitting in the Avon for a while. Four out of eleven recaptures seems improbably high compared to our smolt recapture trials, so it is unlikely that these were all released from the Tommore trap the previous day.

I’ll try to provide a further update before the weekend.

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Tommore Burn smolt trap 2016

The Tommore Burn trap was installed on the 4th March by Jimmy Woods, primarily to test that it was working okay, but it was left in operational mode over the weekend. On Monday morning, to everyone’s surprise, there were 43 fin-clipped presmolts and one fin-clipped 1+ parr. Tuesday’s catch was 24 fin-clipped presmolts and four 1+ parr, with 4 fin-clipped presmolts today and one unclipped.

Since the deployment of the trap last Friday 71 fin-clipped presmolt salmon have been trapped plus a few fin-clipped 1+ parr (which will not smolt in 2016) and one unclipped salmon presmolt. The trap was not deployed until the 20th March last year when the catch in the first eleven days totalled 7 fin-clipped fish. The catch subsequently increased in early April as water levels rose. The total catch of fin-clipped presmolt/smolts in 2015 was 352, therefore the catch in this early phase in 2016 is already 20% of the 2015 total.

The 9am water temperatures have been low, 1.9oC yesterday morning for example, with snow falling nightly.

It is not possible to say at this early stage what the rest of the 2016 Tommore Burn smolt run will be like and as the trap was not put in place until later last year it is impossible to know if we missed a similar early run in 2015. In the past we haven’t deployed smolt traps as early as this because even in the Truim and Tromie (which are located much higher up the catchment) the first reasonable catches were not normally made until about the 20th March.

Most readers will, I’m sure, be aware that the Tommore Burn trap is part of the monitoring associated with the mitigation stocking of this lower River Avon tributary. Fish access is blocked a short distance upstream of the fish trap by an impassable culvert under the Glenlivet Road. The Tommore trap will be monitored daily from now on so that an assessment of the remainder of the smolt run can be made.

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Avon smolt trap report 2015

Finally managed to complete the River Avon smolt trap report for 2015. The report can be accessed by clicking here.

Salmon smolt production was down in 2015 compared to 2014, although the number of trout caught was higher despite lower trap efficiency in the generally higher river levels. Salmon, and trout, smolt age was also slightly less. Two years data is not much on which to base any definitive conclusions, but we can speculate. The differences in smolt production, for both salmon and trout, and the findings of the scale readings could, perhaps, have been anticipated in response to the “Bertha” spate of August 2014.

Comments welcome

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Smolt trap update – a welcome late burst!

This time last year the smolt run was all but over in the Avon with daily catches down to single figures or just above. However no two years are the same and today’s catch of 231 salmon smolts and 29 trout was one of the higher catches this spring. Yesterday we had 156 salmon and 18 trout in the traps, all but two of which were marked and released back upstream as part of our assessment programme to quantify the total run. This morning we recaptured 10 salmon (6.5%) although we may still get more recaptures tomorrow. Even if we get a few more recaptures the smolt run down the Avon last night would have been in the order of 3,000. The river level this morning was 22cm on our gauge but the previous morning, the night when we caught 156 salmon, it was 41cm when the trap efficacy would have been lower – the challenges of trying to quantify the smolt run!

We have completed 12 mark/recapture trials covering a range of river flows from 16 to 47cm, so our strategy of pooling all the results into a single period for the run estimation calculations is probably fair. Overall the recapture rate so far this spring has been 8.96%. As the smolt run is not yet over I’ll refrain from publishing the ongoing run estimate but these nights with catches into the hundreds make a big difference. The basic figures to date are 5,134 salmon (14,035 in 2014)and 678 trout (725) with trap efficiency figures this year of 8.96 % for salmon and 3.3% for trout.

The Tommore Burn trap was removed today as the run was over with only 10 salmon smolts caught in May and 1 in the last ten days. The total number of fin clipped salmon in the Tommore Burn was 357, giving a estimated smolt production of 4.05 per 100m2 wetted area.

With the run continuing in the Avon we intend to operate those traps until the end of May at least – looks like another weekend away from the fishing then!

At the quarterly Spey Foundation meeting today we heard about low smolt trap counts from other parts of Scotland, not all of which were as badly affected by the “Bertha” spate in August last year. I will get some figures from other areas before the final blog on the smolt traps for this spring.

Some graphs below for you to ponder.

Avon salmon smolt catch related to 9am river level.

Avon salmon smolt catch related to 9am river temperature.

Avon salmon smolt catch related to river level

Avon salmon smolt catch related to river level

Avon trout catch related to river temperature

Avon trout catch related to river temperature

Avon trout catch related to river height

Avon trout catch related to river height

 

 

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