254 THE SALMON RIVERS OF SCOTLAND 



I do not believe that the proper conditions for maintenance 

 of the stock of grilse can be secured, if netting is carried on 

 close up to the estuary limits. This netting just at the river 

 mouth was not practised in the old prosperous days of the 

 Thurso. The late Sir Tollemache Sinclair took steps which 

 inter alia secured the preservation of fish approaching within a 

 quite wide area of the river mouth. 



He arranged not only to keep the nets out of Thurso Bay 

 the Scrabster and Pennyland nets but also leased the nets 

 farther west at Holborn Head. He further took a lease of all 

 the Crown Fishings in the district and arranged (1908) to have 

 all those nets removed. The unnetted area became, therefore, 

 about 13 miles, being 9 miles west of the river mouth, and 4 

 miles east of the river mouth. 



Another step was taken in erecting at the outlet from Loch 

 More, a dam-dyke and fish-pass. The dam-dyke raises the 

 level of the loch 12 feet, the purpose being to impound such a 

 quantity of water as will enable artificial floods to be let down 

 the river at will. This action has been taken in view of the 

 success of the dam-dyke built on the Helmsdale at Badanloch. 

 When the Thurso runs too low, when fish become a little stale 

 from lying long in one pool, or when fish off the mouth of the 

 river are unable to ascend, a flood can be let down of sufficient 

 volume to create good " running -water," fish will be moved 

 from pool to pool and will be drawn into the river from the 

 sea. The system employed may now be regarded with some 

 degree of confidence after the experience of the Helmsdale, and 

 the much older but similarly successful experience of "Sixty- 

 one," the pioneer of this class of operation in the Lews. 1 



The dam and fish-pass were designed and constructed by 

 the late Mr. Malloch, Perth. The dam-dyke is in the form of an 

 obtuse angle, the apex being at the natural river outlet. The 

 arm of the angle which runs to the right bank has a bye-wash 

 overflow for storm water ; the arm of the left bank is the 

 longer of the two, and has running alongside of it the gradually 

 ascending fish-pass. The angular design of the dam-dyke is 

 apparently in order to allow an easy gradient in the pass. The 

 wall at the angle of the dyke is 17 feet high, and the length of 

 the main overflow is 310 feet. The fish-pass is 200 feet long, 

 1 Twenty Years' Reminiscences of the Lews, 1871, p. 97. 



