24 THE OYSTER AND THE OYSTER INDUSTRY. 



heavy production and rapid growth of oysters, are, therefore, found 

 better fulfilled at the ends of the reef than at the sides lying across 

 the currents. This tendency to transverse growth once established 

 is increased with every increase in the length of the reef, the jetty 

 effect, retarding the flow of water in one place and accelerating it in 

 another, becoming more pronounced. 



It frequently happens that reefs similar in general character to 

 those just described begin their development from or close to the 

 shore, usually at projecting points. They grow, of course, principally 

 at then- outer ends and extend outward from the shore at right angles 

 to the current, maintaining a nearly uniform width tlu^oughout their 

 length. 



In the foregomg description of natural beds consideration has been 

 given solely to the oyster itself, but the conditions are always com- 

 plicated by the presence of other organisms between which and the 

 oyster there are more or less complex biological relations. Some of 

 the minute forms, especially the plants, constitute the oyster food, 

 while many of the larger species either prey actively on the oyster or 

 its young or compete with it in the struggle for food, oxygen, and 

 space in which to grow. 



DEPLETION. 



Until the last 40 years the majority of the oysters taken from Cape 

 Cod to Mexico came from natural oyster beds which covered an area 

 of such great extent that they were regarded as inexhaustible. That 

 this belief is quite erroneous is shown by the fact that on the northern 

 parts of the coast, where the temperature is about the minimimi for 

 the support of oysters, the natural beds have disappeared or have 

 become sadly depleted. Those of Massachusetts are greatly ex- 

 hausted, and few are found in Narragansett Bay. On the Connecticut 

 coast only two beds of importance remain — one in the mouth of New 

 Haven Harbor and one west of Stratford Lighthouse, near Bridgeport. 

 There are very few in New York waters. Many of the beds of 

 Chesapeake Bay are seriously or quite depleted, although many still 

 remain. From that point southward the depletion has not been 

 nearly so great, as the oyster fishery has not been pursued as vig- 

 orously and the envhonment has been such that the oyster repro- 

 duced much more abundantly than in the north, where a failure to 

 obtain set is only too common. 



In some cases the depletion or destruction of natural beds is the 

 result of natural causes, such as the cutting off of the inlet to a bay 

 or sound and the reduction of the salinity of the water; the covering 

 of the beds with silt, debris, and fresh water during a freshet; the 

 shifting of sand or mud by storms; or the inroads of living enemies. 



The greatest enemy to the oyster, however, is man. Most of the 

 depleted condition of the natural oyster beds is the result of careless 

 overfishing by oystermen. The beefs are stripped down so completely 

 that not enough adult oysters are left to furnish sufficient spawn to 

 insure a subsequent crop. Although millions of eggs and sperma- 

 tozoa are produced, those products are thrown into the water, where 

 many of the eggs fail of fertilization; many eggs and larvaa die or are 

 eaten by enemies; and many fall at setting time on soft bottoms 

 and are smothered. The percentage that finally reaches the adult 



