of the Fishery Board for Scotland. 



13 



that the establishing of estuarine limits from fixed points on either side 

 of the river month, and some distance beyond the limits of all past 

 variation, would in all probability prove a much more satisfactory 

 method of definition. 



The investigations into the life-history of the salmon in fresh water j^".^' 1 ' , ; 

 have been continued along the lines indicated in last year's Report. Dr. h g 

 Noel Pa ton has supplied me with a report by himself and Dr. M. I. 

 Newbigin. This will be found in Appendix V. It is divided into four 

 sections, the three first being by Dr. Noel Paton, the last by Dr. M. I. 

 Newbigin, as follows : — 



(A) Further evidence on the factors determining the migration of 

 salmon from sea to river. 



(B) Male salmon. 



(G) On the nature of the phosphorus compounds of the muscle of 

 salmon, and the synthesis of the organic phosphorus compounds of 

 testes and ovaries. 



(D) Further observations on the source of the pigment of salmon 

 muscle. 



The conclusions previously accepted with regard to the factors 

 determining the migration of salmon from the sea to the fresh water 

 are considered as fully confirmed, viz. : — " That the salmon goes to the 

 sea to feed and returns to the river when it has accumulated its full 

 store of nourishment irrespective of the condition of the reproductive 

 organs. The factor determining migration from sea to river is not the 

 nisus generativus, but the state of nutrition." 



By the co-operation of several interested in the further investigation ^ ln J? n 

 of salmon migration, etc., marking operations have again been con- ' 1 u 

 tinued. The Thurso, Brora, Beauly, Spey, and Tay are the rivers in 

 which marking has been chiefly carried on. A number of marks have 

 again been sent to Ireland to E. W. L. Holt, Esq., Royal Dublin 

 Society. 



In the Answers to the printed Queries issued to] all District Fishery p^^J s to 

 Boards, which will be found in Appendix II., three returns for the year Q uer ies. 

 1898, which were received too late for publication in last year's Report, 

 are here included. They refer to the districts of North Esk, South 

 Esk, and Bervie. I am indebted to Mr. Donald M'Lean, factor to His 

 Grace the Duke of Sutherland, for the returns of the numbers of 

 salmon, grilse, and sea-trout taken in the rivers of East and West 

 Sutherland. 



W. L. CALDERWOOD, 



Inspector of Salmon Fisheries for Scotland, 



