FRESH-WATER MUSSELS AND MUSSEL INDUSTRIES. 



63 



An article in the Journal of Biological Chemistry, 1910, volume 8, page 237, by H. C. 

 Bradley, on "Manganese in the Tissues of Lower Animals" gives analyses showing the 

 proportion of manganese in the ash as taken from a group of nine samples of mussels 

 from the Mississippi River, The high proportion of manganese, as compared with its 

 occurrence in other animal tissues, is of imusual interest, but is without economic signifi- 

 cance as now understood. 



Analysis of Mussels from the Mississippi River showing High Proportion op Manganese 



(After H. C. Bradley). 



Maxuntun 

 Minimmn . 

 Average. . . 



Ash. 



Per cent. 

 23- S 

 13- S 

 16.5 



Manganese 

 in ash. 



Per cent. 

 3-S 

 3-7 

 3-9 



Manganese 

 in tissue. 



Per cent. 

 0,823 

 .500 

 .63 



Total 

 nitrogen. 



Per cent. 



7-37 

 7-37 

 7.24 



UNDERSIZED SHELIvS. 



The most serious waste in connection with the mussel fishery consists in the taking 

 and killing of undersized shells. It is argued by some fishermen that the young mussels 

 should not be thrown back, since a considerable proportion of the mussels taken by the 

 crowfoot die when returned to the water. Several experiments conducted at the Fair- 

 port Biological Station indicate that from 35 to 40 per cent of the mussels taken with the 

 crowfoot and returned to the water die in a short time. However, careful counts of 

 weights of shells actually taken in the mussel fishery and under 2 inches in greatest 

 dimension show that it requires from 33,000 to 174,000 to make a ton, with an average 

 of about 90,000. Should these mussels be returned to the v/ater and should only one-third 

 live to attain a size of 2 inches in greatest dimension, the surviving mussels would weigh 

 much more than a ton, and would thus be of greater value to the fisherman than the 

 entire original quantity marketed as small shells. They would yield a far greater number 

 of buttons per ton, and thus w^ould be of more value to the industry. Furthermore, the 

 larger mussels would have spawned and taken part in replenishing the beds, and thus 

 would have been of inestimably greater benefit to the conservation of the mussel beds. 



