The upper end of Guanica Bay, known as Northwest Bay, or 

 Sugar Mill Harbor, opposite the large sugar irill at Ensenada, has a 

 low area near the mouth of the Loco River that is fringed with 

 mangroves* Along this area are oysters, some of which were found 

 attached to rocks between the tide levels* This area is very small 

 and the greater part of Guanica Harbor is deep water with sandy and 

 rocky shores. 



A brief stop was made at the fishing village of Paraguera, 

 The small islands along the shore are fringed with mangrove trees and 

 ojrsters are present on the roots between tide marks. Most of the 

 bottom here is coral, sand, and rocks, and the water is quite open* 

 At the time of sampling on April 2, the water temperature was 28,2°c*, 

 and the salinity 36*02 parts per thousand. Shifting sand and open 

 water limits the areas where oysters may grow. Starfish and other 

 enemies of bivalve mollusks are present. 



Boqueron Bay is on the western coast facing Mona passage in 

 the Caribbean* This bay is an arm of the sea and is bordered by 

 rocky and sandy shores. Connected to the bay by a very small and 

 narrow shallow passage is a lagoon known as Cana de Boqueron or 

 Laguna Rinoon* The lagoon is about 2 miles long and somewhat less 

 than 1/2 mile wide. It receives fresh water drainage from a con- 

 siderable valley area inland, "fliere is a project under way to 

 construct dams and to utilise for irrigation purposes much of the 

 water which now reaches Boqueron. This change may greatly influence 

 Boqueron for it is within this lagoon that the greatest colony of 

 oysters in Puerto Rico is found, one which is of some economic 

 importance* 



Only the lower half of the lagoon close to the connecting 

 passage to Boqueron Bay was studied closely, flie bottom is a firm 

 shell sand wi th a thin lajrer of soft silt covering it. There are 

 some patches of grass growing on the bottom. At the time of the 

 last of ebb tide on April 2, the water had a yellow-brown appear- 

 ance differing from sea water. This was apparently the result of 

 fresh water from rains which had occurred two days before. Inside 

 the opening to Boqueron Bay the temperature of the water was 27.8 C., 

 and its salinity was 35.19 parts per thousand. Along the shore 

 opposite the entrance and to the northeast where more fresh water 

 drains in from surrounding areas, the water temperature was 28.2 C, 

 and the salinity 34.46 parts per thousand. 



The mangrove trees fringing this lagoon are very dense and 

 their roots are heavily covered with oysters, many of large size 

 compared with those of other areas of Puerto Rico. The largest 

 collected measured 2-3/4 inches in its greatest dimension. There 



