SALMINEN, Kristine/A; GIBB, Alice/C: Is the growth of juvenile rainbow trout allometric?

Traditionally, juvenile and adult fish have been assumed to show isometric growth. However, very few studies have examined this assumption. In this experiment, a lab reared cohort of rainbow trout, Oncorhynchus mykiss, (mass 0.6-10.9 grams) were used to examine the growth of juvenile fish. Digital pictures were taken of the full body of the fish and uploaded to a personal computer. Twelve landmarks were digitized along the perimeter of the body. The digitized landmarks describing the fish were analyzed using the program Morphometrika. The procrutes function within Morphometrika eliminates size and examines all landmark configurations to produce an optimum fit. The thin-plate spline function was then used to produce diagrams representing the bending energy required to transform one shape into another. Smaller fish were deformed into the shape of a larger fish. The diagrams demonstrate allometric changes within the body of the fish. Preliminary results suggest that as the fish becomes larger, the head becomes proportionally smaller, although the mid-section of the fish shows isometric growth. Future research will examine the scaling of the bones of the skull and jaws as well as feeding kinematics in juvenile rainbow trout.