EXTENDED ABSTRACT ONLY – DO NOT CITE

Mechanical shock refers to the force on eggs that occurs as a result of disturbance to eggs. Disturbances can occur during handling (i.e., egg removal from female, pouring eggs into incubators, egg transportation, egg picking) or from outside sources such as pile driving or blasting and seismic shock. To overcome many of the difficulties and uncertainties of interpreting the egg survival responses to mechanical shock, a device was developed at the Pacific Biological Station in the early 1980s to expose salmonid eggs to standardized, quantifiable shock intensities (Jensen and Alderdice, 1983, 1989). The species tested were chinook (Oncorhynchus tshawytscha), chum (O. keta), coho (O. kisutch), pink (O. gorbuscha), sockeye (O. nerka), and rainbow or steelhead trout (O. mykiss). Jensen and Alderdice (1983, 1989) reported changes in shock sensitivity in units of energy (ergs) transferred to eggs on impact, based on the drop height that caused 50 % and 10 % mortality. This standard unit was useful in demonstrating the changes of egg sensitivity during incubation. However, sinc