246 BULLETIN OF THE BUREAU OF FISHERIES. 



2. The anatomy and physiology of the different systems of organs have been 

 described. 



3. The sexes are separate and mature their products at the end of the first year. 

 Single females may spawn from 5,000,000 to 12,000,000 eggs annually. A ciliated larva 

 is formed 4^ hours after fertilization, and when 10 weeks old possesses nearly all the 

 organs of the adult. Under favorable conditions growth amounts to about 1 inch per 

 year for the first three years. After that the rate is much reduced. A mussel bed rep- 

 resents one of the greatest organizations in nature for making flesh food by a short and 

 rapid process. 



4. The food of the mussel is practically unlimited, consisting of plankton organisms 

 (chiefly the smaller diatoms and Protozoa) and detritus. It is possible that some of the 

 dissolved organic carbon and nitrogen compounds are absorbed directly from the medium 

 in which the shellfish are bathed. 



5. Destructive agencies operating against the mussel are storms, shifting sands, 

 extensive growths of eelgrass and other seaweeds which smother them, and a host of 

 predacious enemies, including starfishes, conchs, winkles, oyster drills, dog-whelks, 

 numerous fishes, gulls, ducks, rats, muskrats, seals, and walruses. A parasite, Haplo- 

 sporidium mytilovum, which is described as a new species, destroys enormous numbers 

 of mussel eggs. 



6. In European countries mussels are prized as a food and hundreds of millions of 

 pounds are consumed annually. In France the value of the fishery is second only to 

 that of the oyster. Although exceedingly abundant in many places along our shores, 

 very limited quantities have been eaten in this country up to the present time. Some 

 use has been made of them for bait and fertilizer. 



7. In chemical composition and nutritive value the mussel ranks equal to or superior 

 to any other shellfish. The flesh is tender, palatable, and easily digested. The cost of 

 production and marketing is less than for any other shellfish. 



8. Marketable mussels are generally in season when oysters are out of season. Nar- 

 ragansett Bay and Long Island Sound mussels are usually in prime condition from 

 March to June, while those on the south shore of Long Island are best from June to 

 September. 



9 Fresh mussels only, taken from pure water subject to the ebb and flow of tides 

 and free from sewage contamination, should be eaten. 



10. Mussels are cultivated extensively in France, Italy, Germany, and England, 

 where they yield large returns. At the time of preparing this report cultivation by the 

 bed system was being practiced successfully on a small scale in Cold Spring Harbor, 

 L. I., and in the vicinity of New York with an annual yield of 2,000 to 3,000 bushels per 

 acre. Thousands of acres of unutilized bottom on our north Atlantic coast are adapted 

 to the culture of mussels. 



11. Natural mussel beds, under normal conditions, last from two to four years. 

 Unless utilized commercially before the end of this period they are destroyed by natural 

 enemies or by physical forces. 



12. That the mussel beds on our north Atlantic and north Pacific coasts, if utilized, 

 are capable of yielding millions of pounds of wholesome, palatable flesh food annually 

 is established beyond question. The time has come when we can no longer afford to 

 waste this great natural resource by failure to utilize it. 



