Angler Catch Survey – April and May

Anglers who have fished here at Loch Leven will be aware that, since 2013, we have been asking those that are happy to do so to complete Catch Survey cards as part of a research collaberation with Centre for Ecology & Hydrology (CEH).

Up until about 15 years ago, nearly all fish caught on Loch Leven were ‘chapped on the heid’ and weighed in back at the Pier.  Our detailed fishing records covering over 1 million brown trout go back to the late 1800s. However, since 2000, there has been a dramatic change towards catch & release with around 75% of trout caught on Loch Leven being returned.

Whilst catch & release has to have been a huge help in the recovery of Loch Leven as a wild brown trout fishery, it has completely knackered our historical fishing records!!  The Catch Survey was therefore introduced 3 years ago to try to get data on all brown trout caught on the loch regardless of whether they were kept or released.

1st Catch Survey card for the 2016 season

Until now, all cards have gone straight to CEH where the data is extracted.  It is inevitably pretty time-consuming and so this year, to help them out, we agreed to input all the data from the Catch Survey cards onto an Excel spreadsheet.  We recently completed all the cards for April & May and thought that you might be interested in seeing what initial results have been thrown up.  The one caveat is that we have no pretensions about be statisticians and so what we will show below is derived from the simple raw data and therefore our comments present simply our superficial deductions and we would advise against placing too much importance on the actual figures.

Total Boat Turns 88 273 361
Anglers Cards Completed 20 74 94
23% 27% 26%

As you can see, we had a total of 94 completed Catch Survey cards handed in for April & May which represents 2 just over 1 in 4 of the total boat turns (sessions times boats that went out). However cards are only currently completed by trout anglers whereas quite a number of boat turns will have been by pike anglers (we do not at the moment record what boats are fishing for). In reality, cards were probably completed by about 40% of boats fishing for trout – but that is a guesstimate!

Total No of Rods / Anglers 39 147 186
Total Hours Angling Effort 304 1127 1431
Total Boat Hours 156 584 740

The Catch Survey cards recrd the number of anglers per boat (rods) as well as the number of hours fished. We can show that by the number of boat hours (749 hours in total in April & May) or by the total hours of angling effort (a boat with 2 anglers fishing 8 hours each = 16 hours angling effort) which came to 1431 hours!

Total Fish Caught 28 197 225
Released 18 144 162
% Released 64% 73% 72%

From the 94 completed cards, we were able to see that 225 brown trout had been caught in the opening few weeks of the season, out of which 162 (72%) were released and 63 kept.

Average catch per boat per session 1.4 2.7 2.4
Average catch per boat hour 0.18 0.34 0.30
Average catch per angler per session 0.72 1.34 1.21
Average catch per angler per hour 0.09 0.17 0.16

This is where it starts to get a bit more interesting.  The data suggests that the average catch per boat per session up until the end of May was 2.4 trout and the average angler caught 1.2 fish.  Whilst that looks pretty low against what other fisheries might offer, we have to bear in mind that Loch Leven is a wild brown trout fishery with zero stocking.  All of you who fish on the loch know only too well what a test it is and that recording blanks (more on that later) are just part of the experience. We would like to think that the fishery offers quality over quantity and when you hook a good Loch Leven brownie, it is a memory to be treasured!

We are now sure how meaningful the catch per hour figures are but it would suggest that an angler should catch a brownie on average once every 6 hours 15 minutes  (0.16 fish per hour) – I suspect some anglers will think ‘if only’!

No of boats catching 0 trout 9 23 32
No of boats catching 1-2 trout 7 28 35
No of boats catching 3-5 trout 3 10 13
No of boats catching over 5 trout 1 13 14
Anglers Cards Completed 20 74 94

Talking about ‘blanks’, you can see from above that about one boat in every 3 (32 out of a total of 94) handed in nil returns.  A further 35 boats recorded catching 1-2 fish whereas 27  boats (29%) had 3 or more fish of which 14 were really in the money and 6 or more fish.

No of Trout measured for length 27 124 151
Average Length (millemetres) 415 407 409
No of Trout weighed 11 89 100
Average weight (lbs) 2.08 2.42 2.38

Although we are obviously interested in the numbers of fish being caught, we are also gathering information on the sizes and therefore age groups of the trout.  The above table shows that a total of 151 trout were measured for length and 100 in total were weighed.  Before anyone queries why 151 + 100 = 251 which is more than the 225 fish caught, some were both measured & weighed!

The average length of fish measured was 409 mm which, according to recent data, would suggest an average weight of one and a half pounds, give or take a couple of ounces either way.  And yet the average weight of those fish weighed appears to come in much higher at 2.38 lbs (2 lbs 6 ozs) – why the big differential?  We can only surmise that it tends to be the larger fish that are weighed whereas the smaller ones are more likely to be measured. The true average therefore is somewhere between the 2 figures with a definite bias towards the bottom end of the range. So let’s perhaps say for sake of argument that the average size of fish caught in April & Mat was 1 lb 10 ozs or thereabouts.  We have said it before and will say it again that the average size of the million+ trout caught on Loch Leven in more than a century up to the 1990s was 15 ounces whereas nowadays the average is approaching double that.

Why is this happening?  Who knows?  But we suspect that it is probably something to do with the improvement in water quality over the last decade or more which is now producing an abundance of different foodstuffs for the fish in the loch to feast on.  Whilst this is frustrating for anglers in that it means that the trout are often not so interesting in taking the fly when there are plenty of other food options in the water column, it does mean that the quality and condition of the Loch Leven brownie is better than it has ever been.  Hardly a week goes by these days without someone catching a 6+ pound brownie or someone reporting that they have been broken / smashed by a big trout.

Total Trout measured / weighed 28 197 225
Trout measuring > 480mm / 3 lbs 9 44 53
Trout measuring > 590mm / 5 lbs 0 10 10

As a final thought, we felt that we should try to guage the numbers of bigger fish being recorded.  Whilst we obviously know the weights of those actually weighed (?!), we have tried to estimate the weight of those measured but not actually weighed.  It looks from what we can see that a fishing measuring 480 mm is going to weigh about 3 lbs whereas one measuring 590 mm will weigh about 5 lbs.  Using this as a very unscientific ‘rule of thumb’, it looks as though almost one fish in every 4 (53 out of 225) caught up until the end of May weighed 3 lbs or more and 10 fish weighed over 5 lbs.

Our sincerest thanks go out to all anglers who make the effort to fill in the Catch Survey cards and return them to us and we hope that giving this feedback on the results makes it feel worthwhile.  As and when time permits (extracting all the data from the cards is pretty time-consuming), we will provide further updates during the season.


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