60 THE IMPOVERISHMENT OF THE SEA. 



power, this can best be examined by considering the whole series of 

 years together ; for if the decline in the estimated averages during the 

 decade is to be attributed to errors in the estimated catching power, 

 these errors must include an over-estimation of the catching power in 

 the later years as well as an under-estimation in the earlier years. 



The fall in the averages is so great that any errors responsible for the 

 fall must be of equally great magnitude. The average of the estimated 

 catches per unit amounts to 46-5 tons for the decade. To reduce the 

 average catch for 1889 to this amount would need the addition of 865 

 smack-units ( = 173 steamers) to my estimated total for the year. It is 

 certain, however, that, so far as the steamers are concerned, the error in 

 my estimates is rather an exaggeration than an under-estimation, for no 

 deductions have been made for steamers working on the South and 

 West Coasts, and further deductions should probably have been made 

 for additional Hull and Grimsby carriers. Moreover, whatever minor 

 errors occur in my list of the trawling smacks, they certainly do not 

 amount to anything like an omission of the number above mentioned, 

 which is exactly one-half of my estimated total of trawling smacks 

 for 1889 (Table E, p. 67). 



The same argument applies to the figures for 1898. To increase the 

 estimated average catch to the average for the decade would need the 

 withdrawal of 2,183 smack-units ( = 273 steam trawlers) from my 

 estimated total. The former number actually exceeds the number of 

 smacks estimated for the East Coast in that year, while we have already 

 seen (p. 41) that an estimate of sixty-seven steamers working on the 

 West Coast in that year is probably excessive. The gross number of 

 fishing steamers is, of course, accurately known from the Eegister of 

 British Ships, and my figures are based upon those in the Eegister. 



It is impossible, therefore, to ascribe the fall in the average catches 

 to sulliciently serious errors in the number of fishing boats. 



The remaining estimates which contain sources of error in my figures 

 are the factors indicating the relative catching power of the steam 

 trawlers and of the liners. The sailing liners may be omitted from con- 

 sideration : their small numbers and the high catching power already 

 assigned them render it certain that no error in connection with them 

 can contribute seriously to the discrepancy in the annual averages. The 

 steam trawlers and liners may be considered together, since for the first 

 six years their elHciency has been considered as identical. The coeffi- 

 cients for the conversion of steam trawlers to their equivalents in smacks 

 are based on a comparison of the catches of both classes of vessels in 

 1883-5, but especially the latter year. There can be no doubt, from an 

 examination of the yearly averages of Mr. Alward's smacks, that the 

 catches assigned to the smacks at the period in question were above 



