260 RATE OF GROWTH OF SOME SEA FISHES. 



anchovies observed by Hoffmann were in their second year. This is 

 to some extent true^ for if we suppose that in a cold summer many 

 of the yearling fish would be starved or killed by the cold, of course 

 fewer would survive until the fishery of the following summer, when 

 they would reach the adult condition. But in this case the tem- 

 perature of the summer two years before the fishery would also 

 have a great influence, since the fish would then be hatched and 

 reared, and Hoffmann^s theory only refers to the immediately pre- 

 ceding year. Ehrenbaum mentions that Dr. Hoek has come to 

 conclusions unfavourable to Hoffmann's theory, having found that 

 the exceptions to it are very numerous. In fact, if we examine 

 Hoffmann's records we find that though the years in which the 

 fishery has been unusually productive have always been preceded by 

 an unusually warm summer, the unusually warm summers have by 

 no means always been followed by an abundance of anchovies. For 

 instance, in the years 1861 and 1884 there was no great difference in 

 the summer temperature ; both were above the mean, while in 1862 

 the catch was 9,413 ankers, and in 1885 104,275 ankers. In 1883 the 

 temperature was much below the average, and in the following year 

 the catch was 30,318 ankers. If we compare the magnitude of the 

 catch with the temperature in the same summer we find that a high 

 temperature is usually accompanied by a small catch, and a low 

 temperature by a large catch, and this rule seems to have as few 

 exceptions as Hoffmann's. On the whole, it seems clear that the 

 conditions which determine the number of anchovies which enter the 

 Zuyder Zee are more complicated than Hoffmann's theory supposes, 

 and that much labour and ingenuity will still be required before 

 their exact nature and influence are ascertained. 



Clupea alosa and C. jinta, the Shads. 



My attention was directed to the rate of growth of the anchovy 

 and the shads by the perusal of Bhrenbaum's paper on the anchovy, 

 to which I have already referred. With regard to the anchovy, I 

 am in complete agreement with him; but he seems to me, in correcting 

 Hoffmann as to the growth of that species, to have fallen into an 

 equal error in the opposite direction with regard to the shad. He 

 says there is one clupeoid, namely, Alosa vulgaris and finta (why he 

 calls these two, one, I do not know), which, according to Metzger and 

 Hoek, grows about as fast as the anchovy according to Hoffmann. 

 Metzger supposes that the shads hatched at the end of May reach 

 in the first autumn a length of 6*0 to 10*0 cm. Hoek found at the 

 end of July young shads which were 4*5 cm. long. Ehrenbaum 



