Tracking Contaminant Bioaccumulation in Juvenile Pacific Salmon

Having previously documented the presence of chemical contaminants in fish feed (Maule et al. 2008),we investigated the bioaccumulation of those compounds in Pacific salmon (steelhead, coho and Chinook salmon) from three National Fish Hatcheries.  We hypothesized that after ~18 months in the hatcheries, when these salmon were released to begin their seaward migration, lipophilic compounds that were sequestered in fat would be mobilized and re-deposited in vital organs. Similar re-distribution and resultant physiological dysfunction has been documented in fasting Arctic char (Jorgensen et al. 2006). In order to develop hypothesizes as to the impacts of these compounds, in each hatchery groups of fish were held-back—some were fasted and some fed.  After 14 and 21 d, we examined hepatic gene expression using a directed, cDNA microarray representing several physiological systems.  Results will be discussed relative to effects on survival during the salmon’s emigration.