EGGS AND ALEVINS 73 



8,766. There may have been a loss of, say, 34 in handling the fish 

 and detaching the ovaries, which would make the exact total of eggs 

 8,800, equivalent to almost exactly 900 eggs per pound weight of fish. 



Making the calculation another way I found that 260 counted eggs 

 weighed exactly i oz., so that a pound weight of ova would contain 

 4,160 eggs. As the mass of ova yielded by this fish weighed actually 

 2 lb. 2 oz. presumably the eggs it contained numbered 8,840, 

 equivalent almost to the first result. But 900 eggs per pound weight 

 of fish is slightly in excess of the usual hatchery allowance of 850, which 

 figure may, however, represent a fair average. 



It is not so simple a matter to calculate the number of sea-trout eggs. 

 One can never be certain that the female fish has not already shed 

 some eggs, and the number of eggs varies greatly in different females 

 according to the condition of the fish. Females out of condition, 

 obviously ill-nourished, contain few eggs, and old fish contain relatively 

 fewer eggs than young fish. Possibly 800 per pound weight of fish is 

 a generous average allowance. 



On 1 2th November, 19 14, when collecting sea-trout ova for Luss 

 Hatchery, I looked out for an opportunity of getting a perfectly shaped 

 unspawned female in order that I might count the exact number of 

 eggs she contained. In the afternoon I got such a fish which had 

 apparently just arrived to spawn in a small tributary of Luss Water. 

 It was a beautifully shaped and prettily marked fish of exactly 2^ lb. 

 in weight. We stripped her of her eggs and fertilised them with the 

 milt of a male in a special basin. On arriving at the hatchery the eggs 

 were arranged by themselves on the glass grilles of one hatching box. 

 They were full-sized eggs, as large as average-sized salmon eggs and 

 very rich in colour. As is stated later in the chapter devoted to 

 "Artificial Propagation," each glass tube in Luss Hatchery is a shade 

 over six inches in length and each row of the grille contains comfortably 

 26 eggs, a fact which I verified in this instance by counting the eggs of 



