Presenter: Natasha Mckibben
Mentor: Charles Kimmel
Poster: 22
Major: Human Physiology
Research at Oregon State University has shown that two types of juvenile fish are present in a hatchery stock of spring run Chinook salmon derived from locations along the Upper Willamette River Basin in Oregon. The two groups differ in body morphology, agonistic behavior, growth, and whether they live at the surface or the bottom of the water column. However, they maintain the same diet and identical rearing conditions under captivity. The juveniles appear to resemble wild fish rearing in downstream and upstream sites in the Willamette River Basin respectively, and leave their home streams for the main stem of the river during the same time of year each wild group does. Based on understanding in another species, stickleback, I hypothesize that the fish growing at different depths also differ in their feeding strategies and, therefore, might exhibit changed jaw morphologies and mechanics, even though the genetic basis is unknown. To test this prediction, I quantitatively compared lower jaw bone morphologies in the two types of juveniles at the 50 mm stage. Supporting my hypothesis, I found significant differences between the groups in the shapes of both lower jaw bones, the angular-articular and the dentary. No difference was present in the bone sizes relative to body size. These results provide further evidence that early differences in behavior may be predictive of juvenile life history tactics.