Finavon Castle Bulletin

These bulletin blogs represent news about Finavon and the South Esk, and my views as a riparian owner. They are not the views of any other organisation, nor are they designed to promote the interests of any individual or organisation other than Finavon Castle Water and factors affecting the fishery. Tony Andrews

It would be wrong to think of the South Esk radio tracking project as a failure, because some very interesting data have emerged from it, some of which are rather unexpected. At the end of year one of a three-year project there is much to build upon. So what has been going on in the South Esk and along the coast south of Scurdie Ness? Here’s a summary:

153 multi sea winter salmon netted and radio tagged at Usan, By Montrose, over 14 weeks between February and May 2012

The Greenland west coast & feeding areas of many of our multi sea-winter spring salmon.

Following tagging, some fish were later recorded by receivers on neighbouring rivers:

3 were recaptured at sea.

19 entered the North Esk, of which 6 returned to sea = 13

18 entered the South Esk, of which 8 returned to sea = 10

8 entered the Dee

6 entered the Tay

2 entered the Don

 56 salmon recorded from a total of 153 tagged = 36%

 36% of salmon recorded after tagging is a very satisfactory sample, although it is perhaps disappointing that such a small number of fish entered the South Esk.

April spring salmon 16lbs

 A caveat: 2012 was not a typical year weatherwise for the South Esk; it is important that we take this into account when using data from the tracking project. In a wet year, as 2012 was, salmon behave differently in inshore areas than they do in a drought year. The threat of a mixed stocks fishery to smaller rivers, such as the Bervie, Lunan, or Fife Eden, is greatly increased in a dry summer. In drought years salmon arriving off the coast are liable to congregate in shoals in the larger estuaries, such as in the Tay estuary, or off Montrose, where freshwater flows are stronger, and concentrations of fish become vulnerable to exploitation by nets.

We have no knowledge of stock structures or abundance of most of the rivers affected by the Usan fishery, nor if any population is below sustainable levels (CLs). In effect this means that, while indiscriminate exploitation continues in this way, we cannot take action on any of these rivers to protect fragile stocks. For the three SAC rivers thus affected there is therefore little prospect of Scotland meeting the basic requirements of the EU’s Habitats Directive.

 Usan nets also affect salmon stocks from unknown, distant rivers

The most recent news from Marine Scotland is that two Usan radio-tagged spring salmon have been recorded in the River Don, just north of Aberdeen. That confirms that fish netted at Usan in the early months of the year (16^th February to 31^st May) originate in a wide range of rivers, including the Dee, Tay, South Esk, North Esk and Don. Who knows how many other rivers are affected by the mixed stocks coastal nets at Usan?

If, as may be the case, the Usan nets are killing fish from further afield than the 5 identified rivers, it is of concern that stocks from rivers such as the Fife Eden, and even some of the smaller rivers in the Forth estuary, may suffer damage to fragile stock components from Usan nets in a drought year. However you look at it, the Usan Fishery poses a serious threat to the genetic diversity of east coast MSW salmon, especially in drought years.

 Hard facts means no more doubt

It is now beyond dispute that the Usan coastal nets are a mixed stocks fishery par excellence, surely as indiscriminate and destructive as any drift net fishery. Their very existence ensures that it is impossible to manage the stocks of any of the affected rivers fully effectively. It should be noted that Scotland ended its own drift netting in the North Sea in 1962.

There is no conceivable logic, in the light of the data we now have, which show that the Usan nets are at least as damaging to wild salmon stocks as the Scottish drift nets were, why the Usan coastal nets should not be closed too.

It seems to me that the argument for restricting or ending the Usan Fishery is now overwhelming. Please see the next blog for a more detailed proposition.

TA 16 December 2012

These bulletin blogs represent news about Finavon and the South Esk, and my views as a riparian owner. They are not the views of any other organisation, nor are they designed to promote the interests of any individual or organisation other than Finavon Castle Water and factors affecting the fishery. Tony Andrews

February 2012, when the Marine Scotland radio tagging and tracking project began, now seems a long time ago. I know that there are people who question the value of the project on the grounds that the number of fish recorded as having visited or remained in the South Esk is a small sample and represents less than 10% of the total number (153) of spring salmon tagged in the Usan nets between February and May 2012.

Julian Maclean and Gordon Smith of Marine Scotland fixing a receiver’s aerial at Finavon in February 2012

The last published update of distribution of radio tagged salmon in the South Esk catchment is the 31st of October and shows that a total of 16 fish were recorded as having entered the South Esk . I assume this means that the most downstream of static receivers near the Bridge of Dun recorded their arrival in the river – and presumably those that subsequently left the river “returned to sea”.

Spring salmon in 2012

Of the 16 fish that entered the river, 6 are reported as having “returned to sea”. The remaining 10 fish are distributed within the middle and upper river:

• 5 salmon tagged in May are in the middle and upper catchment, with two in the South Esk above the confluence with the Prosen, one in the Prosen, one close to the confluence with the Quarity Burn and one in the South Esk close to the mouth of the Noran Water.
• 2 salmon tagged in April are in the South Esk, one at the mouth of the Rottal Burn and the other near the A90 bridge at Finavon
• 3 salmon tagged in March are all in the main stem of the South Esk, two in the Justinhaugh/Inshewan area and the third just upstream of Brechin.

As far as the South Esk is concerned, these are the data gathered to date by the project. No fish tagged in February were later recorded.

The 6 salmon that are said to have “returned to sea” should not be ignored because they provide some data on the behaviour of early running (‘Spring’) salmon.

Salmon tagged  by the project team and later recorded in the South Esk and in nearby rivers (Dee, North Esk and Tay) totalled 54 and their breakdown is:

Dee 8 salmon, North Esk 19 salmon (of which 6 “returned to sea”), Tay 6 salmon and caught (presumably by Usan’s nets) “at sea” 3.

So, about 30% (54) of the salmon tagged (153) were later recorded, which, in the light of comparable projects, is quite a good return.

Of the 54 salmon recorded, 12 are reported as having “returned to sea” which gives us 42 spring salmon caught and radio-tagged in the Usan nets, attributed to rivers where they will presumably choose to spawn.

When thinking about the results of the first year of this three-year project I feel there may be some uncertainties which should be taken into account:

1. The technical reliability of the transmitters or receivers may have been at fault, resulting in nil or false readings
2. The possibility that salmon were still feeding in the sea when caught, which might result in their stomachs not having atrophied, and that fish may therefore have regurgitated the transmitters.
3. Transmitters may have been regurgitated or ceased functioning for other reasons.
4. That fish were predated or poached  after being tagged
5. That fish travelled further afield to rivers other than the South Esk’s 3 identified neighbouring rivers
6. That fish were damaged when the radio transmitters were fitted, and in consequence died.

Is catching these salmon at sea the best way to obtain tracking data?

For example:

• 1. Might it be better to catch the fish in the fresh water of the South Esk, or at the very least in the brackish waters of Montrose Basin?
• 2. I recognise that there may be problems in deploying a net and coble crew in the Basin, or in fishing with nets within the river itself.
• 3. Perhaps, by netting spring salmon within the river, salmon which a) had stopped feeding and b) were likely to be destined for the South Esk would then be caught, thus reducing the ‘by-catch’ of salmon bound for rivers other than the South Esk; just a thought.

While the list above does suggest some possible reasons for a partial failure in achieving a larger sample, the fact is that the numbers of fish recorded do constitute a useful sample. If the next two years of the project build on these numbers we can expect some more useful data to emerge on where the South Esk’s Spring salmon spawn, and where in the catchment their progeny spend their juvenile years.

It will be interesting to read Marine Scotland’s evaluation of the project’s first year and in February how the second year’s catches develop.

TA