400 BULLETIN OF THE UNITED STATES FISH COMMISSION. 



North Sea near our coasts, where a firm bottom is found, the area of 

 colonics of young oysters will gradually be enlarged. 



The attempt to plant oysters on the east coast of Schleswig is still in 

 progress. Of the American oysters which had been planted a great 

 many were still alive in September, 1882, when I had occasion to ex- 

 amine the oyster-beds; but no young oysters produced by them could 

 be found. For continuing this experiment I have recommended to 

 obtain American oysters from the outermost limits of the territory 

 where they live ; i. e., from beds where they have been accustomed to 

 the lowest degree of saltness and the coldest temperature which they 

 are able to stand, because the water of the Baltic is less salty and, on 

 the whole, colder than that of the North Sea. 



Within the entire German coast territory of the Western Baltic, from 

 the Little Belt to the west coast of the island of Biigen, the common 

 mussel ought to be used as an article of food a great deal more than has 

 been done hitherto. Only in the bays of Kiel and Apenrade mussel 

 culture has been carried on for some time, by driving trees and piles of 

 beech-wood in suitable places into the firm bottom at such a depth be- 

 low the surface that they remain free of ice. After three or four years 

 the mussels are harvested. Aided by the commission for the scientific 

 investigation of -the German seas fishermen have driven piles for mus- 

 sel-culture in the bays of Kjelstrup and Gjenner; and in the Flensburg 

 Fiord an enterprising fish-dealer has succeeded in changing tolerably 

 large mussels, which originally had a muddy flavor, in some months, into 

 a good, marketable article of food, by placing them in inclosed pens 

 within the water. It is to be hoped that these attempts will be imitated 

 by many fishermen. When large quantities of mussels, of an improved 

 kind, are raised in our bays, a profitable market for them will not be 

 wanting, especially as the mussel is gradually becoming a favorite article 

 of food in the interior of the country. 



My object in these remarks has principally been to point out the im- 

 portant face that the quantity of useful marine animals within a cer- 

 tain given territory is dependent on the co-operation of many different 

 causes, the principal one being the quantity of food found within that 

 territory and the quantity of spawn produced every year. The changes 

 of the temperature of the atmosphere and the sea-water, which are fre- 

 quent with us, will certainly not remain without influenceon the entire 

 vegetable and animal life of our coast- waters, and will either increase 

 or diminish the quantity of food of the marine animals as well as their 

 fecundity. Years of great or limited fecundity are always followed by 

 years of an average increase. Only on these last-mentioned years the 

 fishermen should base their calculations and they will be absolutely safe. 

 They may safely regulate the quantity of implements needed on these 

 calculations, unless they desire more of nature than she can give them 

 according to her immovable laws. 



