31 



LATER STAGES OF GADOIDS 



while the large Haddock are most abundant and the small Haddock least so in the 

 autumn catches. In other words, it appears plain that the secondary maximum of Had- 

 dock about the month of March is largely constituted by the influx of small fish. 



The curves for Cod (fig. 63), for Ling (fig. 64), and for Saithe (fig. 65), all alike show 

 a double maximum in spring and in autumn. In the case of Cod and of Ling the spring 



Fig. 67. Monthly Means of North Sea Catch (in 



cwts.) of Tusk landed at English East Coast ports 



by Steam Trawlers, 1906 — 10. 



Fig. 68. Monthly Means of North Sea Catch (in 



tons of cwts.) of Hake landed at English East Coast 



ports by Steam Trawlers, 1906 — 10. 



Fig. 70. Monthly Means of North Sea Catch (in 



hundreds of cwts.) of Catfish landed at English East 



Coast ports by Steam Trawlers, 1906 — 10. 



maximum is the greater of the two, but in 

 the case of Saithe these two maximums are 

 approximately equal. 



Once again I have drawn out for Cod 

 (fig. 66) as for Haddock a consecutive curve 

 of the proportion of Large Cod in the total 

 catch of that fish for the whole period of five 

 years. The periodicity is clear, clearer even than in the case of Haddock, but on the 

 whole its nature is opposite to what we find in the latter fish. In each year the large 

 Haddock are seen to be at their maximum percentage in the month of March, but again 

 in each year there is a secondary and much smaller maximum of large Cod in he month 

 of September. 



Tusk (fig. 67) shows a very large seasonal fluctuation with a single maximum about 

 the month of April. This period of maximum is of short duration. The catches for 



100 



Fig. 69. Monthly Means of North Sea Catch (in 

 hundreds of cwts.) of Whiting landed at English 



East Coast ports by Steam Trawlers, 1906 — 10. 



