170 SECTION B. VERTEBRATA. 



SECTION B. VERTEBRATA. 



Thursday, 25 August, at 12 noon. 



Cliairman, Mr Saville-Kent. 



r. The Scientific Experiments to test the effects of 

 Trawling in the waters of Scotland, 1886 — 97. 



By Prof. W. C. Mcintosh, F.R.S. 



The paper, of which the following is an abstract, was taken as 

 read. 



These experiments were definitely arranged for by the Royal 

 Commission on Trawling under Lord Dalhousie, and were carried 

 out by the Fishery Board for Scotland — by aid of the small steam- 

 vessel " Garland." Certain lines within the territorial limit of three 

 miles, and certain lines beyond, were selected by the Fishery Board 

 and trawled over in St Andrews Bay and the Forth for ten years, 

 and in the Moray Frith and the Clyde for a shorter period. 



The results, which are combined with other observations, are 

 handled in a different manner from that followed by the Fishery 

 Board. They show no gradual accumulation of fishes due to the 

 closure. The high and low numbers follow each other in such a 

 way as can only be explained by the irregularities and uncertain- 

 ties invariably attendant on fishing-operations. The idea that — 

 because the first five years of the decade had a higher average than 

 the second five years — diminution had ensued, is shown to rest on 

 insecure data. The divergent number of hauls of the trawl respec- 

 tively made during the six winter and during the six summer 

 months in each half of the decade demonstrates the inequality of 

 the circumstances. The results, further, show that the mere closure 

 of the three-mile limit has little or no eff"ect on the fishes, inverte- 

 brates and plants of the area. The distribution of life in the 

 ocean is on too great a scale to be affected by a measure so 

 minute. 



In regard to the individual food-fishes, no proof of the serious 

 diminution of any is made out in these experiments. Some, such 

 as the plaice and the haddock, show considerable variations in the 

 captures throughout the decade. Both follow the general law of 

 having the highest numbers in the warmer months of the year, the 

 maximum being in August. 



