88 



conditions as nearly as possible alike do not necessarily 

 give similar results. This applies with particular force 

 to hauls made with small apparatus and for a short time. 

 As might be expected, hauls made on the same area with 

 large nets and extending over a considerable distance give 

 results which are much more similar than in the cases 

 given above. Three hauls witnessed by Dr. Fulton* 

 illustrate this. They were made by a commercial trawler 

 working in the Moray Firth on September 8rd, 1900, and 

 using an otter trawl with a head line measuring 120 feet. 

 The results were, for the more important fishes : — 



Here the catches are more similar, though in the case of 

 some of the fishes there is a considerable difference 

 between the numbers caught. But it is obvious that a 

 longer haul and with a larger net, must, by merely 

 covering a greater area, tend to eliminate lesser 

 inequalities of distribution. 



(2) The Effect of The State of Tide. 



This is difficult to study since a suitable experiment 

 would necessitate trawling over the same line at least 

 half-a-dozen times a d^ij for a fortnight, and during that 

 time considerable changes in the density of the fish might 

 occur. But such an experiment repeated several times 



* 19th Rep. Scottish Fish. Board, 1901, p. 67. 



