THE IMPOVERISHMENT OF THE SEA. 61 



the average. The increase in 1882 and 1883 has been explained as due 

 to an exceptional extension of the fleeting period ; but even after the 

 latter year, when the fleeting period was reduced to its normal duration, 

 the catches were higher in 1884 and 1885 than during all the subse- 

 quent years included in the table, and were even higher than for a 

 number of years prior to 18S2. Consequently there is some ground for 

 believing that my coefficients for steam trawlers may be below rather 

 than above the true index of their catching power as compared with 

 that of smacks. 



It must be admitted, therefore, that part of the excess in the average 

 catches per unit for 1889-92 over the average catches of the Grimsby 

 smacks for the same years may be attributed to a slight under-estimation 

 of the relative efficiency of the steam trawler. The error, however, thus 

 caused in the amount of the factor is merely a fractional one, and, 

 owing to the great preponderance of sailing vessels at this period, is 

 insufficient to produce more than an insignificant reduction in the 

 average catch per unit during the earlier years of the decade ; whereas 

 the least addition to this fundamental factor produces a far more 

 considerable effect in the later years of the decade, when smacks had 

 decreased in numbers and steam trawlers had greatly increased both in 

 numbers and catching power. If, therefore, my coefficient for steam 

 trawlers at the beginning of the period is regarded as seriously in- 

 adequate (which, I confess, does not appear to be the case), and is raised 

 accordingly, the averages at the beginning of the decade will be un- 

 doubtedly reduced, hut the averages for each successive year will also he 

 reduced to a still greater extent, and the decline in the average catches of 

 North Sea vessels per unit of catching power will be shown to be greater 

 than is actually revealed by my figures. 



On the other hand, if my estimates of the increase in the average 

 catching power of steam trawlers (Table X., p. 48) are based on insufticient 

 data (and I admit the desirability of ampler confirmation), the error 

 arising from this source is also inconsiderable, as may be seen by taking 

 the efficiency of the steamers as a constant quantity throughout the 

 period, subject only to the verifiable increase due to otter gear. 

 Assuming this efficiency to have been fourfold that of the smack (see 

 Table IX.) up to 1895, rising to 5-2-fold in 1898, we still get a con- 

 siderable difference in total catching power of East Coast vessels between 

 1889 and 1898, viz. from 2,673 units in 1889 to 5,029 units in 1898. 

 These figures yield an average return of 64-8 tons of fish per unit in the 

 former year as contrasted with 45*8 tons in the latter year. The rate of 

 fall is reduced by this alteration, but the decrease is by no means 

 eliminated, since it exceeds an average of one ton of fish per unit per 

 annum. 



