Data are presented on the life history of snake pricklebacks, Lumpenus sagitta, collected in Yaquina Bay, Oregon, from June 1977 to October 1978. Specimens were collected primarily by beach seine from four sampling sites in the bay. Snake pricklebacks feed on algae (mainly genus Enteromorpha), on polychaeta (mainly genus Neoamphitrite), on crustacea (mainly harpacticoida), and other bottomdwelling organisms. They were non-selective in feeding. Based on gonado-somatic indices and egg diameter, I found that snake pricklebacks probably spawn near the end of fall and during winter. Fecundity was positively correlated with standard length of the fish and had a correlation coefficient of 0.85. The number of eggs per fish varied from 2,277 to 6,100 with a mean fecundity of 4,089 eggs. Otoliths are more useful than scales for determining the age of the snake pricklebacks. There is agreement between ages as established by the length-frequency method and those established by the otolith method only until age two. The length-weight relationship was described by the model Ln W = Ln a + b Ln L. The value of the constant "b" was lower than 3.0 for both males and females and varied from 2.33 to 2.78. Females showed a larger constant "b" than males during both years of sampling. Length and weight was correlated for males and females and for sexes combined with "r" values ranging from 0.94 to 0.98. In static bioassays, low salinities (<1.0 ppt) and high temperatures (>20.0 C) deleteriously affected the survival of snake pricklebacks. / Graduation date: 1980