Talk provided for the annual Scottish Fisheries Co-ordination Centre Meeting. Held at the Scottish Centre for Ecology and the Natural Environment, Loch Lomond. 4th-5th Feb 2015

1. Monitoring Changes in the Tweed Brown Trout
Population

2. 2014 Brown Trout Catches
• Anglers reported having an
exceptional first half to the trout
season in 2014
• “Best for a long time”
• Some anglers had evenings where
they caught over 30 trout over 10”+
(25cm) in only a couple of hours
• Complaints about there being “nae
troot” went down dramatically (but
some still persisted with some
anglers)

3. Trout Log Book Scheme
• Started in 2006
• Given our with season tickets
• Get around 50 - 80 returns each
year
• www.anglingdiary.org.uk
• 500 - 1,000 fishing trips
• 1,500 - 3,000 hours of fishing
effort
• 2014 catch records confirmed
angling reports

4. Oversize (25cm+) Brown Trout Ave. Annual CPUE/4H – 2006
to 2014
2014 = 16 anglers, 197 fishing trips, 627 hours of fishing effort

5. Oversize (25cm+) Brown Trout Annual CPUE/4H – 2006 to
2014
2014 = 17 anglers, 204 fishing trips, 644 hours of fishing effort

6. Oversize (25cm+) Brown Trout Annual CPUE/4H – 2006 to
2014
2014 = 14 anglers, 115 fishing trips, 370 hours of fishing effort

7. Oversize (25cm+) Brown Trout Annual CPUE/4H – 2006 to
2014
2014 = 10 anglers, 59 fishing trips, 181 hours of fishing effort

8. Oversize (25cm+) Brown Trout Annual CPUE/4H – 2006 to
2014
2014 = 6 anglers, 26 fishing trips, 83 hours of fishing effort

9. Monthly Variations – Lower Tweed

10. Trout Size – Lower Tweed

11. Scale Sampling
• Made an appeal in 2014 for
scale samples for sex ID
• Therefore got more samples
than normal
• One Lower Tweed angler took
samples from every “oversize”
trout he caught
• 64 scale samples collected
• Able to age the trout which
made up the extra catches in
2014

12. Scale Results
• Mix of 2 and 3 winter trout but
majority (90%) of the trout had one
thing in common
• They had just spent their first full
summer and winter in the larger
channels of the Tweed system
• Previous years main stem/larger
tributaries parr)
• For some reason these trout appear
to have experienced survival which
was far greater than normal/average
Typical 2014 season Brown trout

13. 26cm Brown Trout April 2014, 3 winters

14. 27cm Brown Trout May 2014, 2 winters

15. 2014 Lower Tweed Brown Trout
25 – 35cm
River Winters Number %
0 1 2
1 47 89
2 5 9
3 0 0
0
10
20
30
40
50
60
70
80
90
100
0 1 2 3
Percentage
River Winters
Lower Tweed Scale Read River Winters 2014 - 25cm-35cm Brown Trout
(sample of 53 trout)

16. Gala Fish Counter Results –
Brown trout 20-40cm

19. Gala Fish Counter Results – Trout
0
50
100
150
200
250
300
350
NumberRecorded
Length - 5cm Length Class
Gala Fish Counter Trout Length frequency Chart - 2014
0
50
100
150
200
250
300
350
NumberRecorded
Length - 5cm Length Class
Gala Fish Counter Trout Length frequency Chart
Ave. 2008-
2013
2014
Year 2008 2009 2010 2011 2012 2013
Ave.
08-13
2014
Trout Recorded
20cm - 40cm
381 377 232 559 239 304 350 873

20. Why such good survival?
• Short, mild winter (2013/2014)? – Good survival of
Grayling recorded too
• Poor survival of previous 1st River Winter Brown trout? –
prolonged winter 2012/2013 (scale reading)
• Change in migration? – prolonged winter 2012/2013
• Predators? – overwintering Goosander numbers
dropping
• Other factors?