54 



FISH HATCHERY MANAGEMENT 



Table 7. typical biological data organized into a concise format to aid 

 IN developing a rearing program and ultimately designing a hatchery. 



(SOURCE: KRAMER, CHIN AND MAYO 1976.) 



Raceways. 



APPLICATION OF BIOLOGICAL CRITERIA 



The following is a brief explanation of the methodology and format used 

 by Kramer, Chin and Mayo, engineering consultants, in formulating a rear- 

 ing program based on biological criteria. A typical program is used to 

 demonstrate step-by-step planning. Table 7 illustrates how collected bio- 

 logical data can be organized concisely. 



(1) Determine temperature. The first step in preparing a rearing program is 

 to obtain either the ambient or adjusted monthly water temperature ex- 

 pected for use in the hatchery system. Example: 54°F. 



(2) Determine date of event and length of fish. As a baseline for the program 

 projection, the date of spawning of the stock that will serve as parents for 

 the hatchery stocks should be determined. Example: March 15. Determine 

 the date of hatching and initial feeding. Because water temperatures in this 

 example will be approximately 54°F, calculate Daily Temperature Units 

 (DTU) as follows: 54T-32°F = 22 DTU per day. (The standard basis for 

 calculating temperature units is 32°F.) Determine days to hatch, if 300 

 DTU are required to hatch eggs: 300 DTU ^ 22 DTU = 14 days. Adding 

 14 days to March 15 makes the expected hatching date March 29. Deter- 

 mine the day to begin feeding, if 40 DTU are required for hatched fry to 

 develop to feeding stage: 40 DTU -^ 22 DTU = 2 days. This results in an 

 anticipated feeding date of April 1. In this example, 12,000,000 fry are to 

 be released immediately to begin natural feeding in a rearing pond, leaving 



