Reservoir Systems Can Reduce Thermal Shock When Chillers Used in the Incubation of Salmon Eggs Fail

Pathogen free well water used for incubation of salmon eggs produced for restocking in ESA recovery programs may need to be chilled to keep the fish’s development on track with their natural rate.  This ensures fish stocked as unfed fry are released when food supplies are abundant and helps keep cultured fish on growth profiles that match their natural life history trajectory.  Unfortunately, when chillers fail they can produce a rapid increase in water temperature that generates stress that may result in developmental abnormalities or death.  Installation of a reservoir within the chiller system may slow this temperature increase.  Tests conducted with a reservoir equipped chiller system determined that in less than 9 minutes incubation water temperature increased more than 2.5° C when the reservoir was removed.  With the reservoir present, temperature increased less than 0.5° during this same time frame.   Incubation water temperature took 12.7 minutes to rise from 6.2° C to 9.5° C when a reservoir was not present and 76 minutes when a reservoir was present.  The results of these tests were used to calibrate engineering equations for system design and demonstrate reservoirs are useful for reducing thermal shock when chillers fail.