Sea Trout Decline


A Personal Perspective on Declining Stocks

by John Gray


Sea trout, to many of us, rank as the most valuable of all our game fish here in the British Isles, providing unique night time sport on rivers from Cornwall to Caithness, from Connemara to Cumbria. It is therefore very worrying to read reports, in recent seasons, from many parts of the British Isles of a continued decline in stocks of sea trout.

The decline appears to have been particularly severe on the rivers flowing into the Solway Firth. It seems to me that the great problem, on rivers like the Border Esk, is that no one can explain the dramatic decline in sea trout stocks which has occurred there in the last two years. Although 2005 was only my third season fishing that river, my impression is that of a fairly steady, though undramatic, decline in Border Esk sea trout catches over a number of years, in common with many other west coast rivers. 2004, however, saw a dramatic collapse in the run of sea trout, the number of sea trout, that year, representing somewhere between ten and twenty percent of the historical average.

Sea trout would appear to have been in general decline in many rivers for the past twenty years or so. In the absence of extensive scientific data, it is, of course, impossible for an individual angler like myself to see the whole picture. We can only rely on what is often very limited personal experience, perhaps of a few local rivers; on occasional snippets of scientific information reported in the media; on river reports published over half a century in Trout and Salmon magazine; and on official catch statistics published by government agencies such as the Environment Agency in England and Wales and various agencies of the Scottish Executive such as the Fisheries Research Services and a number of District Salmon Fishery Boards. Nor has what appears to me to be a general decline been uniform throughout the country. Indeed, some rivers have reported recent improvements in sea trout catches, in particular those in the North East of England, though I assume that this increase is directly linked to the buy out of the Northumbrian drift nets. It would seem to me, however, that east coast rivers, those flowing into the North Sea, have fared rather better - at least the decline seems to have been less severe - than those on the west coast, this despite the massive over-exploitation of the North Sea sandeel fishery, thankfully now halted, at least temporarily (I must admit to some ignorance on, among many other things, the extent of the sandeel fishery on the west coast/Irish Sea area in recent years).

As to the cause of the decline in sea trout runs, I would list the following as possible suspects:

1. Infestation by sea lice originating on the salmon farms of the Scottish and Irish west coasts. There can be little doubt as to the extent and nature of the problem. Despite the unforgivable refusal of the Scottish Executive to accept the facts, it is clear to many of us that the salmon farms have been a major factor in the decline of sea trout stocks on many west coast rivers.

2. The uncontrolled growth in the populations of both grey seals and common seals around our coastline.

3. The overfishing of sandeels and other marine prey species.

4. Changes in sea temperatures.

5. Netting of sea trout at sea.

6. Diseases such as UDN.

7. Predation by anglers and poachers.

8. Afforestation of the upper catchments and the associated problems of both increased acidification and increased run-off of rainwater

9. Increases in the numbers of protected species of predatory birds, in particular Goosanders.

10. Increases in the numbers of mink.

11. Agricultural insecticides and pesticides which find there way into rivers affecting both fish and invertebrate life.

12. Chemicals used in the control of the Foot and Mouth outbreak in 2001.

13. The use of hazardous sheep dipping chemicals, such as Cypermethrin.

14. The introduction of non indigenous fish species into sea trout rivers, in particular the stocking of farmed brown trout.

15. The increase in runs of salmon in sea trout rivers, putting pressure on limited spawning and nursery resources available to sea trout.

16. Climatic changes resulting in possible changes in the flow regimes of rivers, e.g. extended drought in summer, milder winters and big winter floods.

Many of the above might be linked to the long term decline in our sea trout stocks, while few would explain the dramatic collapse of the Esk sea trout run described above. The effects of agricultural chemicals such as sheep dips and pesticides might merit further close and urgent study. In the Border Esk, for example, my impression is of a decline in the numbers of parr in the river over the past two seasons. This might indicate a new and particular problem in the river to add to all the other problems that have been with us for some time. It would be interesting to learn of rivers where sea trout fortunes have run contrary to the apparent general pattern of decline and possible explanations for any such exceptions.

Little has changed in the past two seasons. The general decline seems to have continued. The Solway rivers - Nith, Annan and Border Esk - show no sign of recovery. What is needed, I think, is concentrated effort in scientific study of the reasons for such a dramatic decline in sea trout stocks. In England and Wales, this would, I believe, be the responsibility of the EA. In Scotland, the Scottish Executive should show a little interest in the subject. I have the impression that the east coast rivers continue to fare better than those in the west. It is perhaps worth mentioning that the Spey, although it has suffered a steady decline in sea trout stocks, still has worthwhile runs of sea trout, as, it would seem, does its near neighbours, the Findhorn and Deveron. Loch Hope, in the north, which appears to have been less directly affected by salmon farming than other once famous sea trout lochs, continues to produce respectable catches.






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