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A Tweed Fisheries Biologist’s Week – Monday 21st November

Monday 21st November: On traps this week, so off up to Peebles and Tweedsmuir in the morning. If no more fish in a day or two  after the recent rain at the top of the river, will take it that the run at Tweedsmuir has finished, which it usually does around this time of year. Office work in the afternoon, preparing for a meeting tomorrow with the EA on the Net Limitation Order for the N.E. England drift nets.

Tuesday 22nd November: Only the Peebles trap this morning, the Tweedsmuir one is at the end of its season and can be done every second day if there is no rain. Collected preservative from the chemical suppliers in Walkerburn as James is starting to collect ovaries from killed fish (mainly at the smokers) to check the published fecundity figure we use (fecundity is the number of eggs a fish has and is related both to body weight and fish age – Grilse have smaller eggs than Salmon). This is to improve our calculation of the number of eggs being spawned upstream of the fish counters. After lunch, at a meeting with the RTC &  EA to discuss the renewal of the Net Limitation Order on the N. E. England drift nets, which expires next December. Finished the day with a couple of freshly dead fish brought in from the lower river for sampling and took the chance to refresh James’ and Kenny’s memory of the pathology sampling procedure.

Wednesday 23rd November: Out to do the traps, nothing again at Tweedsmuir so time to finish there. The Peebles trap doesn’t get fish unless the water level in the burn reaches a particular height and this really has to happen in the middle two weeks of November if any numbers of Sea-trout are to be caught, and this hasn’t happened this year, as it hasn’t in some previous years. We’ve walked the burn below the trap several times trying to work out why it needs this particular, quite high, water level to get fish upstream and can only think that it is some quite extensive lengths where the stream is very wide and shallow  under heavily shading trees – but it’s surprising that Sea-trout should be hindered by such things. If such shallow areas are a sort of barrier in dry Autumns, then it would be useful to be able to identify them throughout the catchment, though how to  define them for identification could be a difficulty.  Back to the office for some more admin and e-mails, then out again to count the Goosanders on the Caddon reservoir.

Thursday 24th November: Out to do the traps with Kenny. A small rise in the water at the Tweedsmuir trap, but no fish again, so took out the sluice gate and disarmed the trap. At Peebles, water still very low and very surprisingly, two female Sea-trout and one little male Brown-trout in the trap, despite what I wrote yesterday! Only once before have we had fish in this trap at below the critical water level. Back at the office drafting a scoping paper on taking forward the work using chemical analyses to distinguish the origin  of trout fry. The results from a small trial run have shown that the tests work and that there are significantly different proportions of particular chemicals in newly hatched fry that have come from Sea-trout eggs compared to those that have come from Brown-trout eggs. This marine “signature” is still found in fry in September but has gone by the time fish are  year old Parr and have fed in fresh water long enough for all their soft body tissues to have been produced from fresh water foods. If we can get the funding to do this work we will, at long last, be able to work out what proportions of the abundant trout fry we find in the burns have come from Sea-trout eggs and what from Brown-trout eggs, showing the strengths and spawning distributions of the two life forms.

Friday 25th November: Usual staff meeting in the morning, then out to do the Peebles trap. The water up on yesterday and two more female Sea-trout, unusually without any accompanying little male Brown-trout. First sleet of the year while measuring them, the first taste of Winter. Back to the office and a meeting about a large, outdoor,  relief model of the Tweed being considered for the Kelso showground that could be used for displays by different organisations working in the catchment.