204 RECENT REPORTS OF FISHERY AUTHORITIES. 



alone in one year is more than 7,000,000 ; and as tliere are three 

 females to two males, we may reckon that over 4,000,000 of these 

 are females. We take, then, 4,000,000 of mature female plaice from 

 the North Sea at Grimsby alone, not to speak of the numerous other 

 trawling ports on the east coast of Britain, and in return we hatch 

 the eggs of 220. The proportion here is one spawner in the hatchery 

 for every 19,090 spawners killed at Grimsby. But next we have to 

 take into consideration the superiority of the artificial process. We do 

 not know what is the mortality of the eggs and fry in the period between 

 fertilisation and the absorption of the yolk, under natural conditions. 

 As we have seen, in the hatchery the mortality is only 12 per cent. 

 Let us assume, for the purposes of calculation, that the loss is only 10 

 per cent, in the hatchery, and is 90 per cent, in the sea. Then we 

 obtain nine times as many fry in the hatchery as in the sea from 

 the same number of fish. It comes to the same thing if we say that 

 one female spawner in the hatchery is equal to nine spawners shedding 

 their eggs, without assistance, in the sea. We may say, therefore, that 

 the work of the hatchery is equivalent to saving 9 females out of every 

 19,090 landed at Grimsby, or one out of every 2,121, or, in round 

 numbers, one out of every 2,000. The disproportion would be very 

 much greater if we took the total number of female plaice landed on 

 the east coast of Britain. It seems to me beyond question, that if 

 we regard the whole North Sea plaice fishery in this way, not taking 

 the numbers caught by foreign fishermen into account, the results 

 produced by the operations at Dunbar will be quite imperceptible. 

 To diminish the destruction of mature fish even by one in every 2,000 

 in each year, could not make any appreciable difference in the general 

 abundance of plaice in the North Sea. 



It must not be supposed that I have any prejudice against artificial 

 hatching, or that I am unable to appreciate the skill and efficiency 

 with which the Dunbar establishment has been organised and operated. 

 On the contrary, I think that Dr. Fulton and Mr. Harald Dannevig 

 deserve great credit for the energy and ability they have exhibited 

 in the working of the first British hatchery for sea-fish, and for the 

 success they have obtained. No harm, but only good, can result from 

 an honest and strictly accurate calculation of the possible results. The 

 evidence available from other enterprises of the same kind tends to 

 show that quite obvious local results have been produced by the 

 liberation of large numbers of fish-larvro in the sea, and although, as 

 the above calculations show, we cannot expect to perceive any increase 

 in the general plaice production in the North Sea, in consequence of 

 the work at Dunbar, it may be quite possible to recognise on particular 

 local grounds an increased abundance of marketable plaice, derived, 



