424 Professor WArcy W. Thompson [March 22, 



The great bulk of the produce of the herring goes abroad, most 

 of it by Konigsberg aud Danzig and Stettin, to those Eastern pro- 

 vinces by the Oder and the Vistula, where even in Strabo's time 

 dwelt the tribe of the Ichthyophagi. But our own food-supply comes 

 mainly from those fishes which, unlike the herring, dwell at the 

 bottom of tlie sea, and are caught, not by net, but by trawl and line. 

 Of such fish the trawler brings in everywhere nowadays the bulk of 

 the supply. In Scotland, owing to the growth of steam-lining, he 

 accounts for but 75 per cent, of the whole, but in England the trawler 

 yields us 93 per cent, of these so-called " demersal " fish, such as the 

 cod and the haddock, the plaice, turbot, and sole : of the last, 

 indeed, he gives us every one. Hence the great modern concentra- 

 tion of this industry in a few great harbours and markets, such as 

 Grimsby and Aberdeen. I show you a diagram of the percentage of 

 all such fish (all fish other than herring) monopolized by Aberdeen 

 alone, which, thirty years ago an unimportant fishing station, now 

 provides us with about 70 per cent, of the whole Scottish supply. 



The English trawling industry, far as it extends, is still busiest 

 and most intense in the region of the Dogger Bank, where every 

 square mile yields over five tons of fish in a year. But this is by no 

 means the richest part of the North Sea, for, measured by the daily 

 catch of a trawler, the quantities steadily increase as we go north- 

 ward ; the kinds, however, are different, and it is the cheaper and 

 coarser fish that swell the northern catch. But I can speak no more 

 on this subject ; I can only show you a few pictures to illustrate the 

 great market of Aberdeen, where 400 tons of fish or more are laid out 

 every morning of the year, a market, however, which Grimsby still 

 surpasses in magnitude. And, by the way, we had an average of 650 

 tons in Aberdeen every morning of last week. 



I have spoken, ever so briefly, of the North Sea as it appears to 

 the topographer aud the physicist, and of the fisheries as the economist 

 and statistician deal with them, but I have said even less of the 

 special studies of the biologist. He has to deal with and investigate, 

 for instance, all the questions appertaining to the food of fishes, to 

 their rate of growth (by means of the rings upon their scales, the con- 

 centric zones of their ear- bones, and in other and more indirect ways) ; 

 by marking living fish he studies their migrations and their diverse 

 rates of growth on different grounds ; and he enquires into the 

 question of their local races and varieties, and all the complex problems 

 connected with their multiplication and their distribution. 



In the end we come back to the ultimate problem of all, the most 

 practical and urgent of problems, the statistical question, whether 

 the fish in our seas are being diminished in number by the operations 

 of man. A whole lecture would scarce be enough for me to explain 

 to you the difficulties of this problem, the methods by which it is 

 attacked, and the preliminary conclusions which we may more or 



