FISH HEALTH MANAGEMENT 293 



when fish are held in different water supplies, each group has to be sam- 

 pled as a separate population. All broodstock of the same species held in a 

 single water supply can be considered one population. 



For a whirling disease inspection, each species of salmonid on the 

 hatchery between 4 and 8 months old in a single water supply is a separate 

 population. Example: A hatchery containing three species of trout between 

 4 and 8 months old with a single water supply has three sample popula- 

 tions. 



Wild salmonid broodstocks must be inspected at least once during the 

 period that eggs are being obtained for a National Fish Hatchery. 



All fish on hand at the time of inspection constitute the population and 

 are sampled accordingly. Samples are collected from each tank or rearing 

 unit. Suspect fish (moribund specimens) are collected along with healthy 

 individuals. Fish should be alive when collected. Necropsy procedures as- 

 sume that the same fish may provide tissues for the various laboratory tests 

 (bacterial, viral, parasitic). A modified procedure may be required for very 

 small fish. Material to be examined for external parasites must be taken 

 before any antiseptic or disinfectant procedures are applied. After the body 

 has been opened aseptically, tissues for bacterial cultures and virus tests 

 are collected. Finally, cartilaginous organs (heads and gill arches) are taken 

 for whirling disease examination. The samples are stored in sealed plastic 

 bags and placed on wet ice for transfer to the laboratory. 



Protocol in the receiving laboratory must maintain the identity of all 

 samples and preclude the dissemination of possible disease agents to other 

 samples concurrently under examination. In addition, procedures must 

 prevent contamination of the samples once the testing begins. 



At least 2 weeks are required for the laboratory analyses to be com- 

 pleted. However, additional time may be required if any complications 

 arise that cause some tests to be repeated or extended. Upon completion of 

 the tests, a certifying official will issue a report specifying the samples 

 taken, the laboratory tests conducted, and the findings. The exact type of 

 report can vary according to the governmental agency involved and the cir- 

 cumstances of the inspection. Based on results of the inspection, a certifi- 

 cate of fish health may (or may not) be issued to the agency requesting the 

 inspection. A copy must be given to the hatchery owner or manager. 



A fish-disease inspection often is trying to a hatchery manager. However, 

 one must remember that the aim of issuing fish disease certificates is to im- 

 prove success in combating diseases on a national scale. The spread of con- 

 tagious diseases has occurred mainly through the uncontrolled transfer of 

 live fish and eggs. In this connection, a clean bill of health helps not only 

 to protect a hatchery owner from serious diseases that might be introduced 

 by new shipments of fish or eggs, but also to assure that hatchery custo- 

 mers receive a quality product. 



