of the Fishery Board for Scotland. 



23 



was 88-9, and for August, 100-1 ; in 1888 the averages were, 33-6 for 

 June, and 111 "3 for August. If the mean of these were taken as 

 representing an approximate average in the intermediate month, July, 

 such averages would be 94-5 for 1887, and 72-4 for 1888, and the 

 average of the 43 hauls for the month would be 77"5, 



The percentage of plaice among the total liat-fishes taken in each 

 month shows the same change, with more uniformity, as might be 

 expected. In the thi-ee periods the i-espective pei'centages are — for 

 September, 405, 29-5, and 29-5; for March, 50-4, 4M, and 28-4; for 

 April, 45-0, 38-2, and 27-3 ; and for July, 39-7, 34-1, and 317. In each 

 case, without any exception, the later period fuinished the lower 

 percentage, and the earliest peiiod the highest. The percentage 

 proportion of plaice among the total flat-fishes for the various months 

 combined in each of the periods is 42-4, 34-3, and 29-5, showing the 

 same variation — viz., successive diminution — as with the average per 

 haul. The average indicates a decrease from the first to the last of lO'l 

 plaice per haul, and the percentage, in the same interval, a decrease of 

 12-9 plaice per cent, of the total flat-fishes. A diminished percentage of 

 one species might, of course, exist along with an actual inci'ease in its 

 numbers (or average per haul), provided other species in the group are 

 present in larger ratio — and vice versa ; but when it exists along with a 

 decreased average, it is evidence that the species has actually, as well as 

 I'elatively, become reduced in numbei'S. 



The averages and pei-centages of lemon soles are much less uniform. 

 The averages in the three periods are — for September, 44'6, 27'1, 10 ; 

 for March, 4-6, 6-1, 5-1; for April, 18-5, 14-6, 213: for July, 20-7, 



