134 



BULLETIN OF THE BUREAU OF FISHERIES 



The largest as well as the deepest of the intercoastal waters included in the 

 general area of study comprised three main bays: Corpus Christi Bay, with its tribu- 

 taries covering about 185 square miles, and Aransas and Copano Bays, covering with 

 their tributaries about 163 square miles. The depth of water in these bays scarcely 

 exceeds 15 feet, and numerous oyster reefs make much of the total area unnavigable 

 to all but boats of the shallowest draft. The bottoms generally consist of hard sand 

 with soft mud present in the vicinity of river mouths, and the water is often turbid, 

 due to the heavy winds that sweep the coast. 



Protected indentations of these larger bays, commonly called coves, arc inter- 

 esting in that generally they are preferred by fish to the more open, larger bays on 

 account of the quiet, shallow water, well supplied with aquatic vegetation and organ- 

 isms suitable for fish food. 



A unique system of smaller bays tributary to the larger ones is common along 

 certain sections of the coast. These smaller bays, typified by Oso and Nueces Bays, 

 which empty into Corpus Christi Bay, are extremely shallow and muddy and inci- 



JAN.ffa MAR. APfi. MAY J(/N. Jt/L. Al/a.5EPI OCT NOV DEC. JAN. fEB. MAR. APfl. 

 /926 mi 



Fig. 2. — Mean air temperature at Corpus Christi, Tex. Solid line, January, 1926, to May, 1927; dotted line 

 represents the averaged monthly mean temperature from 1888 to 1928. (From U. S. Weather Bureau 

 records) 



dentally harbor the bulk of the black-drum population. Their average depth is rarely 

 over 3 feet, and excessive turbidity prevails on account of the quantity of silt brought 

 down by the fresh-water rivers and creeks that empty into these bays. 



Stretching from the southeast corner of Corpus Christi Bay to the mouth of the 

 Rio Grande, a distance of over 180 miles, is the tortuous, extremely shallow Laguna 

 Madre. This lagoon, except in the vicinity of BafBn Bay, has a depth rarely over 2 

 to 4 feet, with a grassy or mud bottom, according to the proximity of sediment-laden 

 rivers or creeks. The northern half of the lagoon reaching from Corpus Christi Bay 

 to Penascal Point in Baffin Bay (an enlarged and deeper portion of Laguna Madre), 

 provides a fine foraging ground as well as a natural trap for the fish that frequent this 

 body of water ; while the general inaccessibility of the region allows the fish consider- 

 able protection from fishing activities. This portion of the lagoon has long been a 

 problem to conservationists, since a heavy mortality of fish life often occurs during 

 the summer months from the excessive salinity of the water, resulting from evapora- 

 tion and lack of rain. 



From Corpus Christi Bay to Baffin Bay the lagoon generally is open to naviga- 

 tion of shallow-draft sailboats; but below Baffin Bay it becomes nothing more than a 



