OYSTER BOTTOMS IN MATAGORDA BAY. 25 



thickness. The clusters are small and foreign growths scanty, 

 though a few shells showed the marks of Martesia, the boring clam, 

 which is so abundant on Half Moon Reef. On April 18 some of 

 the oysters were spawning. 



The flavor, shape, and general condition of these oysters was excel- 

 lent, this being due in part to the persistent tonging on the reef 

 year after year and in part to the extraordinary abundance of food, 

 which is mentioned in the part of this report dealing with that 

 feature of the survey. 



DOG ISLAND REEF. 



Dog Island Reef is the largest and, with Half Moon Reef, eco- 

 nomically the most important bed of Matagorda Bay. With the ex- 

 ception of several narrow channels it forms at low water a complete 

 barrier, stretching from shore to shore a distance of about 3^ miles, 

 with an average w T idth of about 800 yards, and comprises within 

 its limits an area of about 932 acres, exclusive of the crest which 

 is exposed at low water. Its southeastern end is frequently referred 

 to as " Tiger Island Reef," but as the growth is absolutely continuous 

 from shore to shore, the one name is adhered to in this report. 



The reef is a very old one, as may be inferred from its dimen- 

 sions, and its core consists of a mass of shells impenetrable to the 

 steel-shod probe. Excepting where interrupted by the channels this 

 core extends to the very crest of the reef, where it is covered by a 

 sparse growth of racoon oysters, which, owing to the prolonged expo- 

 sures to the air during the low tides of winter, is annually almost ex- 

 terminated and added to the accumulation already existing. This 

 crest, built up by oyster growth and the mud and broken shells 

 thrown up by the waves, extends from within 200 yards of Dog 

 Island to within about the same distance of Tiger Island with but 

 one important break, near the middle, where a channel has been cut. 

 Its extreme width at low water is about 250 yards, but it is very 

 irregular, with many patches which never go bare. The clustered 

 oysters in all parts of the reef bear barnacles and a few mussels, 

 but the latter are never in sufficient quantities to be detrimental. 

 Oystering up to the present time has been almost entirely confined 

 to the vicinity of Tiger Island and the east side. The yield during 

 the season 1904—5 can not be definitely stated, but it is probably not 

 very far from 50,000 barrels. 



North end. — At the northern end of the reef, stretching from Dog 

 Island channel almost to the shore, there is an area of about 113 

 acres which, with the exception of a 7-foot hole near the point, is 

 covered with two feet or less of water during winter low tides. The 

 bottom consists of hard sand and shells with a somewhat greater 

 preponderance of shells near the channel. Several sections indicate 



