SEA-FISHERIES LABORATORY. 345 



Comparison of Nets. 



It may be worth while to attempt to arrive at some 

 estimate of the catching power of each net by considering 

 all the evidence obtained in three years as to the 

 performances of the different nets at the different stations. 

 We shall not take the time of year into account, but as 

 we have some evidence that the years differed in 

 character, we shall in the first instance keep these 

 distinct; it is easy to combine them afterwards if wished. 

 We shall give, then, one figure per net at each locality in 

 each year. For example, we find that the Nansen net was 

 used in 20-10 faths., at Stat. I, 25 times in '09, and the 

 average catch was 2'3 c.c, and the average for all stations 

 (49 hauls) in that year was 2*4 c.c. — a fairly close 

 agreement. 



It is doubtful whether these figures will help us 

 much in forming a true picture of the performances of 

 the nets, except possibly in the totals based on a 

 considerable number of hauls. Looking at the averages 

 for all stations in each year, as shown in the right hand 

 column, it is clear that, as we have pointed out before, 

 the exceptionally large hauls in April, '07, have raised 

 the figures for that year unduly. On the other hand, the 

 catches in '08 were possibly abnormally small. Those for 

 '09 or an intermediate series between those for '08 and 

 '09, would probably be the best approximation to the 

 usual catching power of the net in these seas, and under 

 the conditions employed. Thus the figure for the Hensen 

 net would be about 1 c.c, for the Nansen nearly 2, for 

 the weight net and the fine surface net nearly 3, and for 

 the corresponding net with ? coarser mesh about 5. We 

 have placed the number for the larger nets in a table by 

 themselves, as they are clearly not comparable with the 



