Translation Series No.1211

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the relative amount of eggs in the salmon for practical use. The mean
values vary for different Swedish rivers from 1060 to 1400 eggs per kg
salmon, in the Vistula the valùes lie around 1400. The correlation coef-
ficient is 0.6624 for the Ulme-Xlv, 0.7512 for the river Ljusnan. B. Carlin
(1951) calculated a linear relation between number of eggs and weight of
salmon for fish weighing 2 to 14 kg.
With the aid of very careful statistical analyses, J. A. Pope,
D. H. Mill's, and W. M. Shearer (1961) have treated the fertility of the
Atlantic salmon.. The fish investigated were substantially smaller than the
Swedish salmon and had lengths of 47.5 to 95.0 cm, average 70 cm (about
3.14 kg). Pope et al. found that the changes in the number of eggs oan be
traced to 75 per cent of the different lengths of the fish and only to 7
per cent to the weight of the salmon. The changes in the condition of the
salmon during the upstream migration are reflected in considerable fluct-
uations'in weight. There.does not exist a linear relation between number
of :. eggs and weight of the salmon.
Acording to the authors cited, the relation between length and
number of eggii can be expressed best through the allometric growth formula
N = cL b , where N is the number of eggs, L the length, and c and b are con-
stants. According to . the investigations of Pope et al., b appears to be a
universal constant of the magnitude 2.3345. On the other hand, c character
izes probably the influence of the environment. Annual differences in the
values for one river were not significant, but there were significant dif-
ferences between individual rivers. The above formula can be used generally .
with an error of ± 10 Per cent. Since the fertility can vary significantly
between individual rivers,'we have to expect a priori a greater scattering
• [P. 278 1
of the individual values. for egg .counts of sample catches in the sea than