26 THE IMPOVERISHMENT OF THE SEA. 



to believe (see below, p. 55) that the weather in 1893 also caused an 

 increased abundance of the same kinds of fish (prime, plaice, and 

 haddock). I have not access at present to the detailed temperature 

 returns prior to 186G, and must leave the verification of this suggestion 

 to a later stage ; but the years 1863 and 1864 occur in lists of excep- 

 tionally hot and dry summers (the spring also was hot in 1803), so that 

 there is some preliminary evidence in support of this view. (Eamsay's 

 BihliographT/, Guide and Index to Climate, 188-4, p. 348.) It is unfor- 

 tunate that Mr. Alward's returns do not cover the period from 1868 to 

 1871, since the temperature conditions which prevailed in 1868 were 

 remarkably similar to those of 1893, both in regard to the mildness of 

 the first (winter) quarter, and the exceptional warmth of the spring and 

 summer. 



The possibility of this interpretation should, in any case, be borne 

 in mind, especially as it would, if confirmed, render intelligible the 

 extraordinary drop in the average catches of prime fish after the year 

 1864, as shown by the returns of these Grimsby trawlers. The fall 

 from 458 cwts., in 1864, to 137 cwts., in 1867, is far too rapid to be 

 attributable to the effects of over-fishing under the conditions which 

 then prevailed, but a fall to the same level from 259 cwts., in 1862, 

 would be less incredible as a consequence of such a cause. From the 

 difference in the distribution of plaice and soles it is not improbable 

 that the effects of over-fishing would be earlier shown by the latter 

 species than by the former. 



On the other hand, it is exceedingly improbable that the difference 

 between the abundance of prime fish at the beginning of this period 

 (1860-2) and the scarcity at the end of the period (1888-92), as 

 indicated by the average catches, is attributable to weather conditions, 

 since this would involve the assumption that a type of weather 

 prevailed in the former period capable of multiplying fourfold the 

 normal abundance of these fishes. I do not dispute the possibility 

 of such an increase, but it is so improbable that it would require a 

 very elaborate investigation to establish it as a reasonable hypothesis. 



The returns of both series of Grimsby smacks seem, therefore, to 

 provide unequivocal evidence of a great depletion of the North Sea 

 trawling grounds. Between 1860 and 1892 the average annual catch 

 of prime fish dwindled from at least 300 cwts. to less than 60 cwts. 

 per vessel; the catch of plaice and haddock from about 1,300 cwts. to 

 700 cwts. ; and the total catch (in spite of increased attention to the less 

 valuable kinds of fish) from at least 1,300 cwts. to at most 900 cwts. 



From Mr. Alward's returns, which distinguish plaice from other 

 offal fish, it is clear that the fall in plaice over the whole term of 

 years must have been nearly as great as the fall in prime fish, since the 



I 



