Physiological Changes with Age in Fish 195 



length. No ages were reported. This relationship was des- 

 cribed without rigid statistical treatment, but it is apparent 

 from his diagrams that more refined methods would have 

 produced little change from his value. Farran's formula 

 described the situation except for the largest fish, and it is 

 these that interest us most. The ovary weights and number of 

 ova for these individuals fall below the values predicted by 

 Farran's equation. He recognized this departure and con- 

 ceded that very large fish show a smaller rate of increase in the 

 size of the ovaries than smaller fish. He interprets this growth 

 pattern in the following way: "... that the rate of increase in 

 number (of ova) in fish over 32 cm. in length ceases to cor- 

 respond to the increase in length and either falls off consider- 

 ably or ceases altogether." Contrary to Wynne-Edward's 

 conclusions, Farran's results might indicate that reproduction 

 places an increasing strain on the larger female herring, leading 

 to a reduction in number of eggs. On the other hand, Farran 

 may have simply described the normal course of ovary 

 growth in relation to the body. 



Sensitive to both of the above workers' findings, Hickling 

 (1940) took up the question, this time using the herring of 

 East Anglia. Both of the previous workers had used only 

 weight of gonads in their analyses. Farran had counted the 

 eggs of only three specimens and used the ratio of number of 

 eggs to ovary weight to calculate egg numbers in the remainder 

 of his sample. Hickling counted the eggs of 136 herring of 

 known age and length, and observed the sex, length, weight, 

 and age of 475 additional individuals. 



Hickling agreed with Farran that the rate of gonad growth 

 was greater than the rate of body weight gain in relation to 

 length, and concluded that reproduction became an increas- 

 ingly greater burden to both male and female as they grew 

 larger and older (Table II). Even more interesting is the fact 

 that the weight of the ovaries increased at a more rapid rate 

 in relation to length (L^^^) than the rate of increase in the 

 number of eggs (L^'*^). This was consistent with his analysis 



