Snake River Sockeye Salmon Light Dark Study

This experiment compared the effect of indoor and outdoor lighting on the reproductive characteristics of sockeye salmon reared in a captive broodstock program. Indoor lighting was a mixture of natural lighting filtering through windows and artificial overhead lighting. Outdoor lighting was the product of sunlight passing through a translucent cover on the roof of a tensioned fabric greenhouse structure. Outdoor lighting in the greenhouse was about 80% of ambient sunlight and was about three orders of magnitude higher than the mixed lighting occurring inside the pole building. Fish in both experimental treatments were reared in identical indoor conditions from incubation to the time they would have naturally have reentered freshwater on their return migration from the sea. Maturing fish identified in maturity sorts conducted in late June-early July of each study year were systematically sorted into the two experimental treatments and stocked into the experimental raceways at Burley Creek Hatchery. In 2007, 2008, 2009, 2010 and 2011 these maturing fish were divided into eight similar groups with four groups being stocked into inside raceways and four groups being stocked into outside raceways. Data is also supplied for 2006 when only two inside and six outside raceways were available for the study. Except for lighting the fish were reared and handled similarly. When they were spawned in October and November all adults were assessed for fork length, weight, and ELISA values. The Julian date females spawned as well as the average weight of their green eggs (developed from an individual 10 egg weight sample), total green egg weight, and overall fecundity were determined and recorded. Males were assessed weekly for sperm production with the Julian Date of their first motile milt production recorded, along with their spermatocrit, and slaughtered milt weight. As each female's eggs were split in two lots and fertilized by two different males survival to eye (viability) is based on average survival of the two lots. This average viability was determined for both sexes.

This experiment compared the effect of indoor and outdoor lighting on the reproductive characteristics of sockeye salmon reared in a captive broodstock program. Indoor lighting was a mixture of natural lighting filtering through windows and artificial overhead lighting. Outdoor lighting was the product of sunlight passing through a translucent cover on the roof of a tensioned fabric greenhouse structure. Outdoor lighting in the greenhouse was about 80% of ambient sunlight and was about three orders of magnitude higher than the mixed lighting occurring inside the pole building. Fish in both experimental treatments were reared in identical indoor conditions from incubation to the time they would have naturally have reentered freshwater on their return migration from the sea. Maturing fish identified in maturity sorts conducted in late June-early July of each study year were systematically sorted into the two experimental treatments and stocked into the experimental raceways at Burley Creek Hatchery. In 2007, 2008, 2009, 2010 and 2011 these maturing fish were divided into eight similar groups with four groups being stocked into inside raceways and four groups being stocked into outside raceways. Data is also supplied for 2006 when only two inside and six outside raceways were available for the study. Except for lighting the fish were reared and handled similarly. When they were spawned in October and November all adults were assessed for fork length, weight, and ELISA values. The Julian date females spawned as well as the average weight of their green eggs (developed from an individual 10 egg weight sample), total green egg weight, and overall fecundity were determined and recorded. Males were assessed weekly for sperm production with the Julian Date of their first motile milt production recorded, along with their spermatocrit, and slaughtered milt weight. As each female's eggs were split in two lots and fertilized by two different males survival to eye (viability) is based on average survival of the two lots. This average viability was determined for both sexes.