Oxidative Stress and Senescence Throughout the Migration of Pink Salmon

The energetic and physiological challenges of migration in Pacific salmon (Oncorhynchus spp.) have been well characterized. However, oxidative stress may be a previously unidentified cost of migration. Oxidative stress is caused by an imbalance between free radical production and absorption, leading to irreparable cellular damage that accumulates over time and contributes to senescence. Oxidative stress is becoming a popular parameter used by physiologists to investigate senescence and immune function in various taxa. The objective of this study was to determine if oxidative stress represents a significant cost of migration between river entrance and spawning of pink salmon (Oncorhynchus gorbuscha). Pink salmon were collected from the Strait of Georgia and Weaver Creek spawning channel of the Fraser River watershed, British Columbia. The brain, heart, liver, blood and white muscle were collected. Each tissue was assayed for resistance to oxidative stress using the oxygen radical absorbing capacity assay as well as for oxidative DNA damage using 8-hydroxy-2’-deoxyguanosine ELISA. Results demonstrate that oxidative stress may be experienced differentially between tissues and may be dependent on antioxidant availability and mobility. A decrease in resistance to oxidative stress occurs across migration indicating oxidative stress may correlate with the rapid senescence associated with a semelparous reproductive strategy.