There has been some comment on Tweed following a recent TV programme “Turas a’Bhradainn” on BBC Alba and some have contrasted what they supposed to be the attitude of the Wester Ross Fisheries Trust with the Tweed’s policy on stocking. Coincidentally with the broadcast of this programme, the Wester Ross Fisheries Trust has held a workshop on stocking on May 28th, the report of which can be read HERE. 
 
A common mistake is to think that a fisheries management action that is useful in one place will be just as useful in all others, i.e. that what is useful in one set of circumstances is useful in all. Fisheries biologists are very clear that this is not the case. So, for example, low  fry and parr densities, which might be used to justify a case for stocking, cannot be compared between Wester Ross and the Tweed; any site with more than 2 fry or parr per minute of electro-fishing is graded as “High” in Wester Ross – but such a result would be graded as “Very Low” for either Salmon or Trout fry in the Tweed catchment. The very best sites in Wester Ross yield 8 fry per minute, on the Tweed the best give 28 per minute (though at such high numbers, catching efficiency is reduced).
 
There are also geographical differences between the areas. On the Tweed, the lower grade electro-fishing results for Salmon are largely in fringe areas, where streams are narrowing and trout can start to dominate. Conversely, for trout, the lower grade sites are in larger streams where Salmon dominate. Other places that give low grade results are where there are recognised problems, such as water quality and quantity (e.g. Leet, Eye) or where access is an issue. In such cases, the answer is to treat the cause of the problem (water quality, access) and not the symptom (low fish numbers) which is all that stocking could do. No amount of stocking can clean up even one molecule of pollution or one grain of silt – though the money spent on stocking could.  In Wester Ross however, the low levels of juvenile numbers are widespread throughout the rivers.
 
Given the very different states of the Salmon stocks of the two areas, fisheries management policies are clearly going to be very different. One problem in Wester Ross is that many smolts going to sea get infected with sea-lice from salmon farms and die, severely reducing the numbers of adults returning to spawn. The answer there would be for the salmon farms either to be removed from the migration routes of smolts (as is done in Norway). Another problem is increasingly severe spates in the steep, short, rivers of the area, washing out redds, to which there is no human answer. However, if the causes of a problem cannot be treated, the only thing left to do is to try and treat the symptoms, which stocking may be able to do, in the sense of at least keeping the stocks in existence. Given the very different situation in Wester Ross stocking may well be a useful tool there; on the Tweed it would not.
 
More detail on why Tweed does not have a hatchery can be read HERE.