102 



Appendices to Twenty -second Annual Report 



APPENDIX V. 



AN ESTIMATE OF THE PROPORTION OF THE SEXES OF 

 SALMON IN CERTAIN SCOTTISH RISERS, DURING 

 THE WINTER AND SPRING MONTHS. 



By W. L. CALDERWOOD. 



Information on the important subject of the proportion of the sexes in 

 salmon has been collected in Switzerland, Holland, Norway, and 

 Scotland. Meischer Ruesch* at Basle, in July and November of the 

 years 1878 and 1879, examined 1638 fish. Of this number 609 were 

 males and 1029 were females, but the preponderance of females 

 diminished in August and September, and the sexes were nearly 

 balanced in October — this being brought about, it is stated, by the 

 increase in numbers of male grilse during this month. In November 

 the females are found to be again in excess. Hoek, in the waters of 

 the lower Rhine,t collected statistics inter alia concerning the sexes of 

 fish between the months of October and August for five years. In 

 this time he examined 1822 fish, of which 605 were males and 1217 

 females, but he states that since these were specially selected fish they 

 should not perhaps be taken as altogether representative of the stock 

 of fish in the lower Rhine. Of breeding fish ascending the waters of 

 Holland in October, November, and December, he examined 959, 

 finding 493 males and 466 females, an evenly balanced condition. 

 Like Meischer, he found that this balancing was caused by the presence 

 of " St. Jakob's Zalm " (grilse ?), for of the 493 males examined, 450 

 were " St. Jakob's Zalm." 



With regard to Norway, reference has been made by Archer in 

 the Eleventh Annual Report (Part II., p. 71) as follows : — " From the 

 " returns sent to the Fishery Inspector regarding the sex of the salmon 

 " which were marked, it appears that only 36 per cent, were males, and 

 " the remainder females. This can scarcely be the result of chance, as 

 " about 4000 salmon were marked. They were marked in the late 

 " autumn or winter. On Sands River the disproportion was greater, 

 " being 21 per cent, males to 79 per cent females out of 890 examples. 

 " The numbers netted in October were 193, of which 34 per cent, were 

 " males; in December 406, of which 20 per cent, were males; in 

 " January 177, of which 8 per cent, were males; in February 49, of 

 "which 10 per cent, were males; in April 65, of which 20 per cent. 

 " were males. I may add that 1 have endeavoured to ascertain that 

 " this was not due to the males being on the spawning ground instead 

 "of in the pools by stoning, and, where possible, drifting the net over 

 " these shallows before netting the pool. From the frozen condition of 

 u the tributary streams it would not be possible for these fish to be any- 

 " where else than in the main river." 



* Meischer. Statistische und biologische Beitriige zur Kenntniss von Leben 

 des Rheinlachses im Suss wasser. 1880. Druch von Metzler und Wittig, Leipsic. 



f Hoek. Rapport over Statistische en biologische onderzoekingen ingesteld 

 met behulp van in Nederland gevangen Zalmen. Wetenschappelijk Adviseur in 

 Visscherijzaken. 



