Immune Gene Expression As a Result of Surgical Implantation in Juvenile Chinook Salmon and Steelhead

Telemetry and the use of the Juvenile Salmon Acoustic Telemetry System (JSATS) acoustic micro-transmitters has become a common practice for observing behavior and assessing survival of salmonids, especially in the Columbia River Basin. Acoustic transmitters are normally surgically implanted into the coelomic cavity of the fish. While the data gathered using acoustic transmitters is informative and useful, the process of implanting the acoustic transmitter is stressful and may compromise the immune system of the fish. In order to determine the effect tagging has on the immune system, we used semi-quantitative polymerase chain reaction (qPCR) to measure the expression of several immune genes in the spleen of juvenile Chinook salmon (Oncorhynchus tshawytscha) and steelhead (O. mykiss) during different stages of the tagging process; pre-tagged control, post-tagged, and post-tagged downriver. Interleukin-1 beta (IL1-B) was targeted to measure the non-specific inflammatory response and its expression displayed a typical healing response. Recombination activating gene (RAG-1) and Immunoglobulin M (IgM) were targeted to measure the adaptive immune response. The immune response trends were similar between juvenile Chinook salmon and steelhead; however, juvenile Chinook salmon had a dramatically increased immune response as evidenced by increased expression of all immune genes.