The north coast of Puerto Rico is well exposed to the open 

 Atlantic and is characteristically rugged and rooky with few sandy- 

 beaches. The water is rough the greater part of the time. Since the 

 northern slope and the eastern section receive greater rainfall, the 

 rivers entering the Atlantic are larger than those of the southern 

 coast, which are virtually dry most of the year. The northern rivers 

 are relatively short, however, flowing from the mountainous interior 

 and emptying rather abruptly into the sea. Because of the steepness of 

 the northern coast, the shore dropping off to considerable ocean depths 

 only a short distance from the coast, the mouths of the rivers offer 

 little in estuarine conditions. There are low areas and lagoons in 

 the general vicinity of San Juaji, and oysters are found in this area. 

 Because of the great amount of pollution in the waters near San Juan, 

 this area was considered as not being satisfactory for oj-Bter-growing 

 experiments. The lack of suitable estuarine waters and the rugged 

 nature of the northern coast make it unsuited for oyster culture. 



The southern coast of Puerto Rico, facing the Caribbean Sea, 

 protected to some extent by small islands, points of land, and 

 coral reefs, is not particularly estuarine in character. The rivers 

 of the southern slope are small and have little flow except during 

 the rainy season. This area of Puerto Rico has a much drier climate 

 than others and the beys are highly saline. They have rocky or sandy 

 bottoms and shores except for small areas where surface water enters 

 at times. Here the bottoms are more muddy and are fringed with mangroves* 

 In some places these low sections of the shore are more or less cut off 

 from the bay« and form lagoons. The waters of the lagoons also are salty 

 much of the year. 



■Rie first area examined on the southern coast was Jobos Bay close 

 to Central Aguirre. This bay is shallow except for deeper channels at 

 the lower end close to the dock area. The bottom has a firm mud 

 underlying a soft and sticky surface layer. Patches of grass grow on 

 much of the bottom. The mangrove roots along the shore are well covered 

 in the zone between low water and high water marks with great numbers 

 of small oysters. A few of these have reached a fair size, the maximum 

 between 2 and 2-1/4 inches. The greatest part of the young oyster spat 

 is dead, although oysters of all af^es are present. 7h.e water temperature 

 close to the shore at the time of observation on April 1 was 27. 5*^0., and 

 salinity was 36.33 parts per thousand. Nearer the center of the bay, in 

 8 feet of water, the bottom water temperature was 27.0°C., and the salinity 

 36.56 parts per thousand. 



Guayanilla Ray is open and exposed but a small and very shallow area 

 in the western part may have limited potentialities for shellfish production. 



