THE HISTORY OF FISH-CULTURE. 473 



to the estimate of M. Cnppari, a net reveDue of 80,000 Eoman crowus; 

 that is, abont $88,000. 



The fishers of Coramachio profit, as we see, by the advantages which 

 nature offers, and they have but few precautions to take to insure the 

 development of the fish in this great preserve. The less favorable cir- 

 cumstances in which the fisheries of the Swedish lakes were carried on 

 induced au investigation, toward the middle of the last century, of the 

 means of preventing the considerable loss which the spawn had there to 

 undergo. Already great care was taken in that country not to trouble 

 the fish at the times of their reproduction, so that it was even forbidden 

 to ring the bells during the spawning-season of the bream. A coun- 

 selor of Linkoeping, Charles Frederic Lund,* remarked that the three 

 species most esteemed among those which inhabit the lakes of that 

 country, the bream, the perch, and the mullet, attach their eggs near the 

 banks, either to the rocks, or, by preference, to the twigs of pine and to 

 the willow cages placed in the water to catch them. The eggs are thus 

 destroyed by the fisherman, or devoured by insects, birds, and especially 

 the fishes of prey, so that hardly one out of ten finally escapes. He well 

 understood that the prohibition of fishing during the spawning-season 

 would very imperfectly prevent this enormous destruction. He devised 

 another means of protecting the multiplication of the fish, which accords 

 completely, as he himself remarks, with the habits of these animals, the 

 mode and the laws of their reproduction, as well as with the rules of 

 logic and of our own duty. He caused large wooden boxes to be made 

 without covers, but pierced with little holes, and furnished with rollers, 

 to allow of their descending easily into the water. He placed twigs of 

 pine in them, and introduced a certain quantity of males and females, 

 taken at the time of spawning, taking care to separate them by their 

 kinds and to give them space enough. After having left them there 

 two or three days — that is, during the time necessary for laying the 

 eggs — he drew out all the fishes with the help of a small net, and arranged 

 the boughs so as not to press too much against one another. The eggs 

 arrived at maturity after a fortnight, or a little more, according to the 

 degree of heat, and a multitude of young fishes came forth. This simple 

 process included all the conditions necessary to success, and doubtless 

 great advantages may be found in it for the propagation of fishes whose 

 eggs are adherent. Lund succeeded in transporting from one lake to 

 another boughs covered withst)awn, which he placed in a vase of water, 

 taking care merely not to expose them to contact with the air. In mak- 

 ing a first application of his process, he had put separately into three 

 large boxes, with a small number of males, fifty female breams, which 

 gave him 3,100,000 of the fry ; one hundred perch of the large species 

 produced 3,215,000 of the fry; and one hundred mullets gave 4,000,000 

 of little ones. He obtained then in this manner more than ten millions 



*0f the Planting of Fishes in Inland Lakes. Memoirs of the Swedish Academy of 

 Sciences, vol. 23, 1761. .German translation of Kartuer p. 184. 



