Monitoring Changes in the Tweed Brown Trout Population

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 “naetroot” went down dramatically (but some still persisted with some anglers)

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

Oversize (25cm+) Brown Trout Ave. Annual CPUE/4H – 2006 to 2014

2014 = 16 anglers, 197 fishing trips, 627 hours of fishing effort

Oversize (25cm+) Brown Trout Annual CPUE/4H – 2006 to 2014

2014 = 17 anglers, 204 fishing trips, 644 hours of fishing effort

Oversize (25cm+) Brown Trout Annual CPUE/4H – 2006 to 2014

2014 = 14 anglers, 115 fishing trips, 370 hours of fishing effort

Oversize (25cm+) Brown Trout Annual CPUE/4H – 2006 to 2014

2014 = 10 anglers, 59 fishing trips, 181 hours of fishing effort

Oversize (25cm+) Brown Trout Annual CPUE/4H – 2006 to 2014

2014 = 6 anglers, 26 fishing trips, 83 hours of fishing effort

Monthly Variations – Lower Tweed

Trout Size – Lower Tweed

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

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

26cm Brown Trout April 2014, 3 winters

27cm Brown Trout May 2014, 2 winters

2014 Lower Tweed Brown Trout25 – 35cm

River Winters Number %

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1 47 89

2 5 9

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Lower Tweed Scale Read River Winters 2014 - 25cm-35cm Brown Trout (sample of 53 trout)

Gala Fish Counter Results –Brown trout 20-40cm

Gala Fish Counter Results – Trout

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Length - 5cm Length Class

Gala Fish Counter Trout Length frequency Chart - 2014

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Length - 5cm Length Class

Gala Fish Counter Trout Length frequency Chart

Ave. 2008-2013

2014

Year 2008 2009 2010 2011 2012 2013Ave.

08-132014

Trout Recorded 20cm - 40cm

381 377 232 559 239 304 350 873

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?