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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