MISCELLANEOUS SHELLFISH INDUSTRIES 



673 



are under and behind the foot, and solidifies as soon as it comes into contact with 

 the water, thus forming a thread. A number of the threads form the "beard" 

 which enables the mussel to anchor itself firmly. Many thousands of mussels are 

 often seen thus attached to each other on acres of tidal flats at low tide. The foot 

 of the mussel is a brown- or purple-colored muscular organ; its tip is able to 

 exert suction by means of which the mussel is able to take firm hold of any hard 

 object. 



Mussels feed on diatoms and other microscopic forms, larvae, etc. They grow 

 rather slowly, requiring from 1 to 8 years to reach maturity. In Europe seed 

 mussels from 2 to 3 years old are often collected and planted until they reach 

 marketable size; this requires from 2 to 5 years. The rate of growth depends upon 

 the temperature, the amount of food, and the rate of movement of the water. The 

 most rapid growth is usually obtained, other conditions being equal, in the bottom 

 of the tidal streams where the mussels are never uncovered and where there is no 

 deposition of silt. Under such conditions mussels occasionally reach a length of 

 3 inches in a single year. 



Composition. The edible portion of mussels contains a relatively large amount 

 of protein compared to oysters and clams. The edible portion of scallops contains 

 a higher percentage of protein, and that of oysters contains more carbohydrates. 

 But, since the mussel shells are thin and light, the proportion of refuse is much 

 smaller and so the total amount of nutrients in a bushel of mussels is considerably 

 greater than in the same quantity of any other common shellfish. 



Field (1922) reported experiments by Alsberg and Clark and Bennett which 

 indicate that sea mussels are about as easily digested as hard-boiled eggs and 

 nearly as completely digested as raw beef. The composition of whole mussels 

 and the edible portion of mussels is given in Table 151. 



Table 151. Composition of Sea Mussels. 



Source: ^ Atwater, W. O., and Bryant, A. P., "The Chemical Composition of American 

 Food Materials," U. S. Dept. Agr., Office Expt. Sta. Bull, 28, Revised (1906), and 

 - Field, I. A., "Food Value of Sea Mussels," U. S. Bureau of Fisheries Bull, 29, 85-128 

 (1909). 



Methods of Fishing. Mussels are very easily taken, in most cases, as they 

 often lie attached to each other in huge beds in relatively shallow water. Dredges 

 are ordinarily used in taking this shellfish and usually yield large returns for the 

 amount of labor expended. Because of the danger of contamination with decom- 

 position products mussels that are exposed at low tide are seldom taken for food. 



In Europe rakes as well as dredges are used. Rakes are usually preferred as 

 they do not crush the shells nor cause the sand to shift over the bed. The common 



