slower-growing animals to serve as broodstock. If differential 

 growth is hereditary, this practice will produce smaller animals 

 and result in lower production levels. 



Knowledge of the genetic characteristics associated with economic 

 traits is essential. Without knowledge of how to control and 

 manipulate reproductive activities, year-round production of seed 

 stock or fingerlings is difficult. Gene pool maintenance is also 

 essential, if further advances in breeding are to be made. 



Growth and Behavior 



Growth rates and behavior largely determine the potential for 

 culture and the manner of rearing a particular species. 

 Information is needed about factors such as metamorphosis, optimal 

 growth conditions, feeding behavior, and feed conversion 

 efficiency. 



The aggressive and cannibalistic character of some species, such as 

 the American lobster ( Homarus americanus) necessitates use of 

 individual grow-out containers. The extra cost associated with 

 maintaining animals individually represents a major drawback to the 

 economic culture of animals with these behavioral characteristics. 



Nutrition and Diets ' ■■ ^" - -':' ■ ' 



Clinical techniques used in various fields of animal science for 

 determining nutritional status have not been developed tor 

 important fish. Although data on nutrient requirements for 

 salmonids have been used to formulate diets for other species of 

 fish with reasonable success, there is a need to develop complete 

 and inexpensive diets that meet the specific nutritional 

 requirements of each species and to determine proper feeding 

 levels. To complicate matters, nutritional requirements and diets 

 vary for specific species during different stages of their life and 

 reproductive cycles. Lack of a suitable diet to maintain larvae 

 until they can eat processed foods is a serious drawback to the 

 culture of several species. Agricultural and fisheries by-products 

 also need to be examined for their feed value in aquacultural 

 production. 



Environmental Requirements 



Minimal information is available about the environmental 

 requirements (for example, oxygen, salinity, space, and 

 temperature) of certain species at different stages in their life 

 history. Such information must be obtained before the species can 

 be raised commercially. 



Facility Engineering, Construction, and Operation 



Insufficient knowledge of fish stress tolerance, water chemistry, 

 water quality and temperature control, optimal harvesting and 



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