Meeting Abstract
Fish use their fins for propulsion and maneuvering in a three-dimensional environment. In addition, many fishes use their fins for more specialized behavior like crawling or holding onto the substrate. The bony, segmented fin rays (lepidotrichia) support and control the relative shape and position of the fins, and are therefore critically important for fin function. The yellow perch, Perca flavescens, is a species that uses its fins for a variety of behaviors. For example, the pelvic fins can be used to interact with the bottom as well as for maneuvering in the open water. Here, we examine the variation in stiffness of the fin rays both within and among the paired and median fins of the yellow perch. It is not always possible to get fresh specimens, here we investigate how preservation techniques, (fresh vs. freezing and preserving with formalin followed by storage in alcohol), affects fin ray stiffness. We performed three point bending tests using an Instron model 5942 testing apparatus to compare stiffness in a sample of fin rays from all soft fins (pelvic, pectoral, soft dorsal, anal and caudal) of the yellow perch. For all specimens, we found that the pelvic rays were significantly stiffer than the other fins and the pectoral fins the least stiff. We also found no significant difference between fresh and frozen specimens in fin ray stiffness. We predicted that the fixed fin rays from the preservation in formalin and storage in 95% ethanol would be stiffer than the fin rays of fresh and frozen specimens. We found that preservation in formalin resulted in decreased stiffness of smaller rays, < 25 mm long. Overall, the trends in the relative stiffness among the fins was consistent in all specimens, regardless of preservation method.
