VI PRACTICAL METHODS OF INCREASING THE SUPPLY I41 



hatchery as a business enterprise, then clearly the question for 

 that firm is whether the resulting increase in the catch of fish is 

 sufficient to pay for the cost of the hatchery and leave a profit. 

 The nation in the actual state of matters is such a firm, and 

 hitherto no attempt has been made to ascertain from reliable 

 and complete data whether the working of a hatchery is com- 

 mercially profitable or not. 



In the meantime we may well take some trouble to consider 

 how far the operations of a hatchery can be profitable, reasoning 

 as accurately as possible from what we know of the facts bearing 

 upon the question. The Scottish Fishery Board calculates that 

 if one in a hundred of the fry distributed from the Dunbar 

 Hatchery in its first two years ultimately came into the market 

 and realised 6^. each, the resulting value would be ^18,000 ; but 

 the great majority of the fry were plaice, and },d. each is a fair 

 average price for plaice on landing. One in a thousand sold at 

 \d. each would realise about ^300. The number of plaice eggs 

 obtained at the Hatchery in 1895 were forty-four millions, and 

 the number of plaice fry liberated 38,615,000. Now we may 

 take the average number of eggs produced by a female plaice to 

 be 200,000, as indicated by the figures given in Chapter HI. 

 Therefore the number of eggs above is the produce of 220 

 female fish. According to statistics collected by Mr. Holt, four 

 million mature female plaice are landed per annum at Grimsby 

 alone. So that for 19,090 spawners killed at Grimsby, the eggs 

 of one are hatched at Dunbar. It may however be supposed 

 that the mortality or destruction in the sea between the shedding- 



o 



of the eggs and the stage of the absorption of the yolk in the 

 larva is greater than in the hatchery. We may suppose that the 

 destruction is nine times as great in the sea, which is certainly 

 more than the actual proportion. In that case one spawner in 

 the hatchery is equal to nine in the sea, or the total result of the 

 work of the hatchery is equivalent to leaving in the sea one 

 mature female out of every 2,000 killed at Grimsby, a proceeding 

 which would clearly not make much difference to the total supply 

 of plaice in the North Sea. 



It may be said, however, that it does not matter how limited 

 the extent of the hatching operations may be, so long as the 

 marketable fish produced are sufficient to give a profit on the 

 cost of the operations. This at present we can neither prove nor 



