ECONOMIC ZOOLOGY 



is to get the proper legislation enacted by ignorant or dishonest 

 legislatures. 



There are various difficulties with which the oyster farmer has to 

 contend. If the water be too cold the oysters may grow but not repro- 

 duce; if it be too shallow it may freeze in exceptionally cold weather; 

 the salinity of the water may not be right. 



Although there are no known epidemic diseases of oysters, there are 

 several enemies that cause trouble; the worst of these is the starfish, 



as has been noted in connection 

 with the Echinodermata; while 

 not found in the southern beds it 

 is so numerous and destructive 

 farther north as to make oyster 

 culture impossible without active 

 warfare against this enemy. They 

 multiply very rapidly, where con- 

 ditions are favorable. The best 

 means of destroying them is to 

 catch them on a " tangle," Fig. 

 32, of frayed rope and then kill 

 them by plunging them into a 

 tank of hot water. If cut to pieces 

 and thrown back into the water 

 the menace is increased, as many 

 of the pieces will grow into com- 

 plete starfish and thereby increase 

 the total number of the pests. 



There are several snails, known 

 as "drills" that are often quite 

 destructive by boring through the 



shells, especially of young oysters. There are several fish such as the 

 drum, sheepshead, skate, etc., that are injurious; and the oysters are 

 sometimes smothered by mussels, sponges, sea-weeds and drifting sands. 

 Oysters are collected with tongs or by dredging. The former, 

 Fig. 33, might be compared to a pair of heavy iron rakes with very 

 long handles that are joined, scissors- wise, near the rakes. The tonger 

 may stand in the stern of a row-boat or at the side of a larger boat 

 and by a scissors motion scrape off the oysters from the bottom until 



PIG. 32. A "tangle" of frayed rope 

 or cotton waste used to collect starfish 

 from oyster beds. (After J. L. Kellogg, 

 Shellfish Industries, from U. S. Fish 

 Commission.) 



