of the Fishery Board for Scotland. 



47 



NOTE II. 



REPORT ON CERTAIN SALMON INVESTIGATIONS' conducted 

 on the River Tweed during the Netting and Rod Seasons of the 

 year 1894. By James R. Tosh, M.A., B.Sc. 



During the netting season of last year on the Tweed, a number of 

 investigations into salmon questions were carried on for the Fishery Board 

 at Berwick, by Mr R. H. Grey, of the Royal Welsh Fusiliers. Shortly 

 after the close of the netting season he was ordered to join his regiment, 

 and was unable to prepare a report on his work. His papers were handed 

 over to me by Mr Archer, Inspector of Salmon Fisheries for Scotland. 

 Mr Grey's work on the rate of growth of the genitalia of salmon was 

 continued by me at Kelso during the last six weeks of the rod season. 



Rate of Growth of Genital Organs of Salmon 



The genital organs of all the salmon and grilse, that were opened at the 

 Berwick Salmon Company's Fish House, were measured and weighed. To 

 determine the rate of growth of these organs their weight has been calcu 

 lated in percentage of the body weight of the fish. The percentages have 

 been averaged over almost equal (ten-day) periods in each month, the last 

 period extending from the 21st to the end of the month, after the method 

 of Dr P. P. C. Hoek. These averages may be taken as an indication of 

 the rate of growth. In the case of male fish, the ducts were always 

 weighed with the testes. From one male, 7 lbs. weight, caught on 28th 

 March, three testes were extracted, all of the same size and weighing 

 together just over \ oz. The additional gland, which occupied a median 

 position, had no duct, but was otherwise normal in structure. Up to the 

 end of May, the testes of the male salmon are very small. During the 

 succeeding two months they increase very little in size, but in the month 

 of August there is a very rapid growth, after which there is again a gradual 

 increase, until maturity is reached. Unfortunately very few fish could 

 be examined in September and October. The rod season on the Tweed in 

 the neighbourhood of Kelso was very poor. Throughout October the 

 river was very low, no fish could get up, and those in the river were only 

 taken with much difficulty ; while a series of floods in the beginning of 

 November enabled the fish to get far up the river at once. These excep- 

 tional circumstances caused a break in the observations, which in a 

 normal season would never have occurred. Ordinarily I should have seen 

 about 200 fish per week at Mr Steel's curing establishment in Kelso, 

 whereas only 74 were got during the whole season. The genitalia of the 

 female salmon increase from less than 1 per cent, of the body weight in 

 March to about 20 per cent, at the spawning time. Up to the end of 



