223 
state that contrary opinions have been expressed. It is at 
first sight a paradox that year by year the total catch of 
fishes in British waters should increase, while the fishing 
grounds may be really deteriorating. Along with this 
increase in total quantity of fish caught, however, has 
gone on a marked increase in the catching powers of the 
fishing fleets and an extension of the area fished over. 
The introduction of steam into fishing vessels about 1850, 
and the use of ice for preserving the catches, made possible 
the use of larger and more efficient apparatus (the otter 
trawl latterly), and enabled the vessels to make longer 
voyages. With this change the small sailing boats began 
to decrease in numbers, and fishing instead of being car- 
ried on by vessels independently owned by masters or 
crews, became a great capitalised industry. 
Therefore although the annual catch has gradually 
increased, the average catch per vessel is now beginning 
to decrease, and the density of the fish population in the 
seas round the British Isles is less than it formerly was. 
The catches of 4 Grimsby sailing trawlers for every year 
since 1875 have been published by Garstang,* and all of 
these shew a marked decrease with hardly any fluctuations. 
In Danish seas the same decline has been noticed. 
Petersent has shewn that there has been a steady decrease 
in the size of the Plaice landed for many years, and it is 
obvious that the reduction in size of the fish landed is 
indicative of the reduction in number of those present on 
the fishing ground. 
*See Garstang Mar. Biol. Assoc. Journ. for these figures and the 
elaboration of the above argument. 
+ 4th Rep. Danish Biological Station, 1893. 
t From the relation between the average size at first maturity and the 
average size of all mature plaice captured, the change in the fish population 
of an area may be deduced, See Kyle—18th An. Rep. Scottish Fish. Bd., 
1900, p. 200, 
