as an inexpensive source of animal protein for Caribbean Islands 

 and similar regions where freshwater resources are limiting 

 (Watanabe, Wicklund, 011a, Ernst and Ellingson, in press). 

 Although not indigenous marine species, tilapias were identified 

 as the finfish group best meeting important criteria established 

 by CMRC including, acceptance as food fish, ease of breeding and 

 rearing, ability to utilize a variety of inexpensive feeds of both 

 plant and animal origin, and adaptability of culture methods to 

 lesser developed regions. In addition, euryhaline tilapias are 

 generally able to tolerate a wide range of salinities, suggesting 

 a potential for culture in brackishwater or marine systems. 

 Suitability for high-density culture in cages was also considered 

 an important attribute that would permit farming in coastal 

 waters, thereby minimizing costs associated with construction and 

 maintenance of land-based production systems. 



The blue tilapia, Tilapia aurea ( 0. aureus ) , was initially 

 selected for seawater culture trials in the Bahamas. In a 

 preliminary study conducted in October 1984, fingerling T\ aurea 

 averaging 21.2 g were reared for 90 days in 1.0-m3 floating cages 

 placed in concrete seawater (34-37 ppt ) ponds on Lee Stocking 

 Island (McGeachin, Wicklund, 011a and Winton, 1987). Disease, 

 high mortalities, and poor growth, indicated that T\ aurea was not 

 a suitable species for cage culture in full seawater. 



Subsequent studies revealed that Florida red tilapia, a hybrid 

 strain originally derived by crossing Oreochromis urolepis 

 hornorum (female) with 0^ mossambicus (male) (Ernst, Ellington, 

 011a, Wicklund, Watanabe, and Grover, in press), were highly 

 tolerant of seawater, and studies on culture methodology were 

 initiated. Experimental work has sought to obtain basic 

 information on the biology of the Florida red tilapia hybrid with 

 respect to salinity tolerance as well as to assess production 

 performance in seawater. Work has also begun to extend saltwater 

 cage culture of Florida red tilapia to other areas of the 

 Caribbean Basin, beginning in Haiti. In this paper, recent 

 progress in experimental saltwater culture of Florida red tilapia 

 is summarized. 



THE EFFECTS OF SALINITY ON GROWTH OF FLORIDA RED TILAPIA 



Growth of juvenile, monosex males at different salinities 



Little information is available on the influence of salinity 

 on growth in tilapias. The effects of salinity on growth of 

 Florida red tilapia, previously unknown, were studied in juvenile, 

 monosex males under controlled photoperiod (12 L: 12 D) and 

 temperature (28°C). A high euryhaline capacity of the Florida red 

 tilapia strain was evidenced by faster growth rates in brackish 

 and seawater than in freshwater, although results appeared to be 

 modified by stocking density. At a high density (20 fish/200-1 

 tank), growth in freshwater was comparable to growth at 10 ppt 



338 



