OYSTER BOTTOMS IN MATAGORDA BAY. 65 



cold weather a number of dead drums were observed near Mad 

 Island and at other places. The oystermen state that at times con- 

 siderable damage is done at Half Moon Reef and on other beds in the 

 lower part of the bay, but apparently there is less danger to appre- 

 hend above Dog Island Reef, though there is no reason why the fish 

 should not be found there at times. 



Mussels. — The mussel may be regarded as one of the passive ene- 

 mies of the oyster — that is, an organism which injures it not by 

 direct attack, but by appropriating to itself certain things which the 

 oyster requires, in this case food and space in which to grow. As 

 will be shown in a following section of this report, the oyster feeds 

 mainly upon microscopic plants called diatoms, of which there is 

 a more or less limited supply in any given body of water. Investi- 

 gation has shown that the food of the mussel consists of these same 

 organisms, and its consumption of food consequently lessens by so 

 much the supply available for the oyster. An abundant growth of 

 mussels therefore may render inadequate for the oyster a natural 

 fertility of the water otherwise quite sufficient, and beds which if 

 clear of mussels would produce oysters of good quality are thereby 

 rendered of but little economic value. Moreover, if crowded by its 

 fellows or by foreign growths, the oyster assumes elongated or irregu- 

 lar shapes, the shells are shallow, and the meat is generally inferior ; 

 in other words, it tends toward the raccoon type. The young mus- 

 sels under favorable conditions attach in large numbers to the 

 oysters, and as they grow with great rapidity they soon form dense 

 masses, which fill all available space in the clusters and crowd the 

 oysters to the point of starvation and suffocation. In a number of 

 places in Matagorda Bay numerous instances were noted in wdiich 

 the mussels had grown in great masses over the lips of large oysters 

 and had actually killed them. 



In addition to the damage wrought thus, the mussels operate in other 

 ways to injure the beds. By presenting entanglements they tend to 

 collect seaweeds and other debris, which serve to stifle the oysters; 

 and they very much interfere with culling, because, unlike oysters, 

 they can not be knocked from the clusters, but, owing to their tough 

 attachments, must be laboriously pulled off, leaving rough, unclean- 

 looking debris behind. 



In Matagorda Bay mussels are found in varying numbers on prac- 

 tically all of the oyster beds, but below Dog Island do not constitute 

 a markedly objectionable feature. They thrive best in water of low 

 salinity, and in the extreme upper part of the bay they constitute a 

 serious menace to many of the beds. It was stated by persons fa- 

 miliar with the region that they have developed to this extent only 

 within a comparatively recent period, mostly since the permanent 



