The 2009 radio tagging programme has commenced this week where our team of biologists Dr Lorraine Hawkins and Adrian Hudson from the River Dee Trust are out and about on the lower river beats. They are working closely with the River Dee Ghillies who are contacting them by telephone when an angler hooks a fish. They arrive quickly to the beat and carry out the tagging process with the assistance of the ghillie and carry out some data capture relating to the fish.They insert a radio transmitter and a floy tag, measure and take a sample of tissue/scale for analysis and then allow the fish to recover and swim away.
The fly caught Salmon being brought to the tagging facility
The Salmon ready to be tagged
This year the programme consists of radio tagging 60 fish, with 30 being tagged before the end of September, and 30 being tagged during the first fortnight in October. This is part of a 3 year study programme which allows angler to fish until the middle of October on the beats below Aboyne bridge. This will allow the biologists to ascertain where in the catchment the tagged fish are going to spawn and it will also show that catch and release does not cause mortality if carried out correctly. Over the next few months the biologists and bailiffs will be seen on the catchment with detection equipment where they will be picking up the transmitted radio signals enabling them to map out the fishes journey through the catchment to their spawning grounds. There will be regular updates about the programme throughout the autumn and winter so please look in regularly for up dates.
Monitoring the upstream migration of the Salmon to the spawning grounds where the next generation are born
Movement of radio tagged fish- update 18/10/2009
Since the River Dee Trust fitted radio tags to 60 salmon in late September and October, tracking has found that 24 of these fish have made significant movements in the river. The spawning period is approaching and these salmon will be returning to the stretch of river where they lived as juveniles to produce their own offspring. The upstream migration of these tagged salmon seems to have been spurred on by two periods of higher river flows (11th and 15th October), in which a total of nine salmon migrated upstream for the first time. One male salmon (at 23 lb in weight, the largest fish in the project) swam seven and a half miles upstream within 24 hours and is now nine miles upstream of where it was caught by an angler on 5th October. However, another male salmon has - after spending almost a month close to where it was first caught and tagged - now turned around and swam nine miles downstream. This is not what salmon typically do before spawning and it will be interesting to see if this fish swims upstream again. No doubt some of our tagged salmon are going to defy what the text books tell us!
Movement of tagged fish 26th October
Tracking the radio tagged salmon was made rather difficult at the end of last week due to the river flooding – a lot of access tracks alongside the river were underwater! In the last week, 17 fish moved (generally short distances) downstream, which may be related to floods. 19 fish have moved upstream in the last week, with the greatest journey being made by a 7 lb male fish that swam from its capture site at Park 10.5 miles upstream to Cairnton. Another male (19 lb in weight) moved upstream 8.5 miles from Upper Drum to Banchory, though subsequently dropped downstream 2.5 miles, all within a few days. The fish reported last week for moving downstream 9 miles continued downstream a further 4 miles, reaching the tidal limit, then turned and swam rapidly upstream in one day and is now 1 mile below where it was captured and tagged (at Park) in September. Overall since the project started, 26 of the tagged salmon have moved significantly upstream (up to 10.5 miles) and 11 have moved downstream (the greatest downstream movement being 13 miles), with the remaining tagged salmon showing no directional movement (typically milling around a few pools).
Movement of tagged fish 30th October
The high water levels associated with the flooding on 22nd October encouraged 11 of the radio tagged salmon to move upstream, some great distances. Two male salmon (both caught at Park fishing beat in 3rd week of September) have moved 32 miles upstream and are currently residing at Cambus O May and Monaltrie, below Ballater. It has been predominantly male salmon that have moved the greatest distances to date; three other males have so far reached Aboyne. The fish that has been reported in the last two weeks for moving downstream to the tidal limit and then upstream to where it was caught (at Park by angler John Waggott) entertained us further by continuing upstream another 21 miles to reach Aboyne.
The movements of the tagged salmon are detected not only by staff members who track the fish from the bank side, but also by static receivers placed on the bank side which automatically log when tagged fish moved past. This equipment has found that the tagged fish have been moving upstream at rates of up to 1 mile every 1.5 hours. The receivers also show that fish are moving throughout the day and night; although so far there has been more migratory movement during the period of early evening.
Movement of tagged fish 6h November
Further flooding on the 2nd November has made tracking of the tagged fish difficult as parts of the lower river have been inaccessible and in addition, signals emitted from the radio tags are reduced in strength (as fish take cover from high waters under banks and behind big rocks). Tracking has therefore been carried out daily since the flood. We have found our first tagged fish in a tributary – the River Muick, which enters the Dee at Ballater. This fish has swam upstream 39 miles since being caught at Park in September, and is none other than the one caught by angler John Waggott, mentioned in previous reports. As spawning is now occurring in the upper tributaries, it is likely that this fish will spawn soon or is currently. We have located a total of six fish in the upper river so far (i.e. above Aboyne), of which five are males. A further 12 fish have moved into the Middle Dee (i.e. between Banchory and Aboyne), but the majority (42) are still in the Lower Dee at present.
Movement of tagged fish 13th November
This week most fish have shown some movement, but the overall picture of two thirds of the tagged salmon in the Lower Dee and the remainder of the fish spread throughout the Middle and Upper Dee still stands. A two further fish have now entered tributaries, closing in on their spawning grounds. Firstly, a female fish (which entered the river in the middle of September) has progressed approximately 1.5 miles up the Beltie burn (west of Banchory). Salmon have started spawning in this burn, but the peak spawning activity will probably occur in the next week or two. The second fish to enter a tributary was a male fish caught at Park in September (which had already been in the river for several months). It has moved into the Pollagach burn, a small burn between Dinnet and Ballater. In terms of the fish that have shown most upstream migration so far, they have been predominantly males, which had likely been in the river for several months previously. To date, the group of fish tagged in September are showing a similar distribution to those tagged in October.
Movement of tagged fish 30th November
In the Upper Dee (above Aboyne), the spawning period for salmon peaked in the first couple of weeks in November and spawning activity is now declining. Some of the radio tagged salmon in the upper river appear to have spawned and have begun dropping downstream. However, after spawning, not all salmon will survive (those that do swim downstream and eventually out into the sea again). One radio tagged female salmon (caught and tagged at Lower Crathes in September) had entered the Dinnet burn and swam 5 miles up the burn, travelling through Loch Davan, to reach a spawning area. Whether she was able to deposit her eggs is unclear because very little was left of her carcass when it was found in late November, after she was presumably taken by a mink or otter. A male salmon (tagged at Lower Crathes in October) was also tracked to 11 miles up the River Tanar, having entered the Tanar around the first flood waters of October 21st. It hopefully spawned, but the tag has now been tracked to an area of flood deposits, showing that the fish is now dead. A second male salmon (caught by ghillie Jim Paton on October 5th) also entered the River Tanar in November and was recorded at a spawning area. After one week it left the Tanar and returned to the main stem. In some of the deeper waters in the River Dee, this fish has a better chance of surviving the winter.
The peak spawning period for the lower river is also likely to have occurred in the last week, but there is still a lot of salmon spawning to come this season. The radio tagged fish in the lower Dee have not shown as much movement but there is an abundance of salmon spawning areas in the lower Dee.
Movement of tagged fish 14th December
Few of our radio tagged salmon now remain in the Upper and Middle river reaches (above Banchory), as these fish have finished spawning and have either moved downstream or (in three cases) are dead. In total, 21 of the 60 tagged salmon have swum upstream but now moved downstream again. Only two fish appear to have left the river (being recorded at an automatic listening station in Aberdeen), presumably after completing their spawning; the first fish left in mid November and the second left around 13th December. However, many of the spawned salmon will instead over-winter in the river.
A lot of the tagged salmon in the Lower Dee are not yet showing downstream movement, though they may by now have spawned. There are also 13 fish (predominantly females) that have shown little migration since they were tagged in September/October, suggesting that these fish had arrived at their final spawning destination earlier in the season and then waited patiently. Still, salmon spawning in the Dee has not yet finished for the season and will still be occurring in January, and possibly February, so some tagged fish may still migrate upstream.
It is interesting how salmon that were all in the same stretch of the river in September and October can go on to such diverse spawning locations: the tagged fish spread throughout the river from Maryculter to Ballater, with at least seven fish that entered tributaries, including the River Tanar, River Muick, Beltie burn, Pollagach burn and Dinnet burn. Tracking will not be undertaken during a 2 week period over Christmas, however, automatic listening stations will be up and running which will allow long-distance movements of tagged fish to be detected.
Radio tracking update 25th Jan
The 60 salmon that were implanted with radio tags in September/October 2009 were monitored throughout the salmon spawning period. Spawning peaked in November and now as most spawning has finished the radio tracking is being wound down, until our next programme begins in autumn 2010. Our radio tagged fish tended to reach their maximum upstream migration in early-mid November, tying in with the observations on spawning time. The majority of fish that had moved upstream began to drop downstream by the end of November. Whilst spawning does occur into January and even (at very low levels) in February on the Dee, only one of our 60 tagged fish are currently migrating upstream (a female that entered the river in the autumn) and has probably yet to spawn.
In total, 37 (61%) of the fish moved upstream since they were tagged, so even fish that had been in the river for many months left some of their spawning migration until the last minute! Nine fish (15%) moved downstream and the remainder have shown non-directional movements in this period. Upstream migration averaged 13 miles between the autumn tagging and spawning time, although eight fish migrated more than 25 miles and the greatest distance migrated was 37 miles, upstream of Ballater. Seven fish (12%) entered tributaries such as the River Muick and River Tanar, showing the importance of tributaries for producing salmon. Four of the tagged fish are known to have died (in late Nov-Dec) and a single female fish has left the river; the particularly cold weather may have deterred other fish from swimming downstream and leaving the river. However, six fish have moved downstream into the Aberdeen area, so soon will leave. The others will leave the river (or else die) before late May.
The River Dee Trust will produce a full report on this study in April, where individual fish tracks will be reported (and anglers can learn the subsequent movements of their fish!). A full comparison of the salmon tagged in September 09 and those tagged in October 09 will determine whether or not the trial extension of the fishing season (from 30th September to 15th October) may be affecting the spawning movements and behaviour of salmon, which will influence the decision on whether the fishing extension is made permanent.
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