74 fish hatchery management 



Table 10. recommended hatchery pond loadings (pounds of fish per gal- 

 lon PER MINUTE INFLOW), BASED ON DISEASE CONSIDERATIONS, FOR CHINOOK 

 AND COHO SALMON HELD IN 80 x 2()-FOOT PONDS. THE VALUES REPRESENT FINAL 

 POND OR RACEWAY LOADINGS AT TIME OF RELEASE OR HARVEST FOR FISH SIZES OF 

 1000 FISH PER POUND AND LARGER. LOADINGS SHOULD NOT EXCEED THE TABLE 

 VALUE BEFORE TIME OF RELEASE. INFORMATION IS NOT AVAILABLE FOR OTHER 

 TEMPERATURES, SIZES, OR SPECIES OF FISH. (SOURCE: WEDEMEYER AND WOOD 1974.) 



their length have a density index equal to 0.5. A useful formula to avoid 

 overcrowding raceways is: 



W = D X FXZ. 



Where W = Permissible weight of fish 



D = Density index (0.5 suggested for trout) 



V = Volume of raceway in cubic feet 



L = Fish length in inches 



Raceway or pond volume requirements can be calculated with the for- 

 mula: 



V=W^{D XL). 



Volumes of circular tanks can be determined from Table C- 1 in Appendix 

 C. 



This concept of space requirement assumes that the Density Index 

 remains constant as the fish increase in length. In reality, larger fish may 

 be able to tolerate higher densities in proportion to their length. This 

 method has proved to be a practical hatchery management tool, nonethe- 

 less, and can be used with any species of fish for which a Density Index 

 has been determined. 



