— 42 — 



Thus the average-weight per hour in 1903 was nearly double the average- 

 weight in 1904 and in 1905, while in 1906 it rose somewhat. 



We get very interesting results from a comparison between weights and 

 numbers. The big rise in numbers from 27 in 1904 to 48 in 1905 is imperceptible 

 in the weights. Of course the explanation is that the increase in numbers is due 

 to quite small haddocks, whose weight is practically negligible. The effect upon 

 the weights is only perceptible later, and we meet with a rise accordingly from 

 1905 to 1906. The numbers increase from 1904 to 1906 by a good 160 %) whereas 

 the weights do not rise more than 30 "/o- We cannot therefore draw any 

 direct conclusions relative to the bulk, from the total number of 

 individuals. A large number of haddocks does not of necessity imply a heavy 

 weight (high value for the catch), nor conversely do heavy weights necessarily 

 imply large numbers. 



The reason for this becomes obvious if we examine the proportional weights 

 of the different market-groups for each of the years between 1903 and 1906 and 

 employ the same method as when studying the advance of the numerical 

 proportion. Fig. 29 shows the average catches for the different years — the 

 broken lines denoting numbers (cf. page 21). By converting the numbers into 

 weights, as previously explained, we obtain weight-curves which are here denoted 

 by the completed lines. The varying average-weights of the different market- 

 groups are perfectly clear. 



The following are the values found, expressing the average-weights per trawl- 

 hour (Extra Large being left out of account): — 



Kilos per hour Average' 



in 1903 1904 1905 1906 



Large 27 2'6 2'6 1-5 



Medium 4-1 3-6 2-0 I'O 



Small 7-5 2-0 1-3 2'9 



Extra Small . 1-5 03 1-5 5-9 

 (over 21 cm.) 



Unmarketable o.i o-i i*2 0-3 0-3 (0*4) 



Total... 15-9 8-6 8-6 ii-6 ir2 (11-2) 



The average-weights show considerable variations from year to year for the 

 smaller groups. We find the greatest differences in the Extra Small group (1904 

 = 0-3 kilos; 1906 = 5-9 kilos) and in the Small group (1903 ^= 7-5 kilos; 1905 = 

 1-3 kilos). Medium vary much less (1903 ^ 4-1 kilos; 1906 = i-o kilos): while 

 Large show very slight variations in the first three years, after which in 1906 

 the weight decreases to nearly half (1903 = 27 kilos; 1906 = i"5 kilos). 



These results tally nicely with the English market statistics for 

 haddock taken within the North Sea and landed on the East Coast of England 



• The first column |shows the total averages given on page 40. The figures in brackets give 

 the mean averages of the four different years and will be found to agree very well with the total 

 averages. 



