Pike Tagging
on
Loch Lomond
Loch Lomond Pike Tagging Study (1992-96)
by Bill Little
INTRODUCTION
The Loch Lomond Pike tagging Study began in the early spring of 1992 when 10 'Bravehearts', otherwise known as the tagging trustees, from the Glasgow & west of Scotland Regional Association of the Pike Anglers Club of Great Britain & Ireland ventured forth on the 'big pond'. But before that eventful day, many months of hard work had been undertaken to ensure the project 'got off the ground'. Before a study such as this is undertaken it is vitally important to establish the aims of the project. To this end, we approached the University of Glasgow Field Research Station at Rowardennan, and together we came up with four main aims:-
- To assess the current pike population, and
- To assess the size class/age structure of the Loch's pike, and
- To assess the degree of mobility of pike within the Loch, and
- To assess growth rates of Loch pike.
plus, any other beneficial information.
So now we had the committed anglers to do the actual tagging and the project 'goals' were defined, now all we needed was the funding. This is where the Pike Anglers Club of Great Britain and Ireland (PAC) came in. Many people will probably think that PAC is purely concerned with catching pike but nothing could be further from the truth! Their mission statement shows that they are concerned with the 'bigger picture' as well. It states, "The Pike Angler's Club of Great Britain and Ireland will work to establish an environment in which pike are valued, both as a sporting fish and a necessary part of the management and ecology of fresh waters." That says it all and when approached they were only too willing to fund the project. The rest, as they say, is history!
RESULTS
Since 1992, a total of 517 pike have been tagged at approximately 20 locations around the loch. Of these 173 have been recaptured at least once. Several fish have been recaptured on numerous occasions including one fish which has been banked or boated 11 times in 12 months. The overall recapture rate has hovered between 25 and 33% for the last couple of years but there have been marked differences in the recapture rates between the north and south basins of the Loch. The deep, steep sided northern basin of the loch is less fertile than the shallow south basin with only a few pike holding areas. As a consequence, the pike population of the north basin tend to be more static and localised than their south basin counterparts and as a consequence are more easily located and recaptured. The recapture rate for the north basin is approximately 54% whereas in the southern basin it is around 27%. As would be expected, the recapture rate trend is rising each year. The more fish that are tagged, the more likely they are to be recaptured.
YEAR
TAGGED.
RECAPS.
TOTALTAGGED
TOTALRECAPS.
|
RECAP.RATE
|
1992
195
28
195
28
|
14.4%
|
1993
75
43
270
71
|
26.3%
|
1994
121
28
391
99
|
25.4%
|
1995
75
55
466
154
|
33.0%
|
1996
51
19
517
173
|
33.5%
| | | | | |
| | | | | | | | | | | | | | | | | | | | | | | | |
Periods of liberty (i.e. the time between tagging and the latest recapture) has ranged between 1 hour and three years. Some of the fish have given the impression of having disappeared completely BUT then they have reappeared more than two years later in exactly the same place as their previous capture! Where they went during this period may perhaps be explained later when pike movements within the Loch are discussed.
POPULATION
These early results showing a relatively high recapture rate (levelling out at around 33%) seem to indicate that the Loch's pike population is not as high as some might have expected. (Whilst the results tie in with my own informal studies on the Loch, over 20 years, I am wary of reading too much into the results based on only a few years tagging.)
MOVEMENTS
Approximately 80% of the pike recaptured showed what fish biologists call 'strong site affinity' in other words they displayed territorial tendencies, the other 20% were wanderers. (However, at this point it should be remembered that for the most part, we have not got a clue where they might have been between the tagging and recapture.) It would however appear to confirm a feeling that many local pike anglers have had for the past decade, that there are two distinct types of pike on Lomond - those who are 'ambush feeders' and those who are 'active hunters'. These fish differ quite markedly in appearance. The 'hunters' being the archetypal pike - lean, fit, beautifully marked and fin perfect. The 'ambush feeders' on the other hand tend to be fatter and a bit tatty in appearance with split fins, etc.. Most of the movements have been along a shelf/contour line, e.g. along the Endrick Bank which runs from Balmaha Pier (NGR NS 415 908) towards Portnellan (NS 404 873) and beyond . This is as expected but what we hoped for was to find some evidence of fish moving from east shore to west shore or even a south basin fish turning up in the north basin or vice versa.
It took a while but eventually it happened. A pike tagged near Luss (NS 364 928) in August 1992, which was recaptured in the same spot 11 months later was recaptured at Ardlui (NN 318 155) in March 1994. This entailed a journey of 18 miles over the deep northern basin which is akin to a freshwater fjord, i.e. steep sided with no obvious food holding areas. Why did she do this? (I say she because at 20lbs/9.5kg plus there can be no doubt.) Did she follow a run of 'black nebs' (small sea trout) heading for the River Falloch? Did she go to Ardlui to spawn, possibly because this was her birthplace. Do pike return to the place of their own birth like salmon? Who can tell. It seems that tagging programmes can throw up more questions than answers, at least initially, but by revealing at least some partial clues about fish behaviour, the programme allows these questions to be more accurately directed in future.
Whatever the reason for her travels, she confounded us all in October 1994 by turning up off Luss exactly where she was tagged, coincidentally to the same angler who tagged her! By this time she was going back in condition, losing weight and pretty obviously 'on the way out'. 00237 you may be gone but the questions you threw up will ensure your memory never fades! Another fish, has completed a tour of the south basin from Endrick Mouth (NS 423 896) to Portnellan (NS 404 873) to Rossdhu (NS 363 898) to Endrick Mouth again and a small jack pike has made the long journey from Ardlui (NN 318 155) to Inchtavannach (NS 367 913). This latter fish having disappeared for 2 whole years before re-appearing in the south basin. Is this what happens to the disappearing pike? Do they go 'walkabout' to areas of the loch where few anglers venture? Several other specimens have 'vanished' for long periods before turning up again, usually at the original tag site. Where have they been in-between times?
GROWTH RATES
At present no analysis has been done on growth rates of Loch Lomond's pike. From my own informal work, growth rates can be anywhere from 2.5 to 4.5lbs (1.1kg to 2.0kg) per year. But further tagging needs to be done to allow this analysis to be done on a more long-term basis. Anomalies can creep into the data, such as in 1994, when the massive algae bloom put the pike completely off the feed for an extended period of time. It took the pike two years to fully recover the ground lost during this horrendous period. This type of occurrence needs to be taken into account when analysing the data and the easiest way to do this is to take a long term overview, a few years down the line from now.
So there we have a brief overview of the Pike Angler's Club of Great Britain & Ireland's tagging programme on Loch Lomond. At present, we await the preliminary report prepared by the University Research Station at Rowardennan. My thanks go to The Pike Anglers Club of Great Britain & Ireland, The University Research Station at Rowardennan and all the many pike anglers who have contributed to this project. For anyone requiring more information on the tagging programme or if you catch a tagged pike and wish to report it, please contact the author or Davy Holt
This update was prepared using data up to 31/12/96.
Pike Tagging
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