Brian Kim: Researching Fish on the Potomac

Students record the length of live caught fish before returning them to the river.

My name is Brian Kim and I am a member of the OSCAR fish team at the Potomac Science Center (PSC). Over the course of this summer, I have been going out to Gunston Cove and Hunting Creek located within the Potomac River to collect fish species. My research focuses on assessing the diet items of the fish species and determining if there is a significant difference between the two locations as well as any differences in submerged aquatic vegetation (SAV) and non-aquatic submerged vegetation (NSAV) areas within each location. The most enjoyable part of this experience has been the process of the actual fish collection. There have been two separate trips for each location where we would use a series of seine nets, fyke nets and trawls to catch fish from as little as 10 mm to as large as 530 mm. The trawls were the most thrilling method because we usually caught the largest specimens during each trial. As each trawl was hauled onto the boat, there was a rush of excitement as to see which specimens we caught and how many. Once we had recorded all required data on each fish, the samples were taken back to the Potomac Science Center to begin the process of answering the question “What exactly has each fish species been eating?”

Five juvenile fish that were the last meal of a yellow perch.

The majority of my time at the PSC has been spent dissecting the stomachs from the fish samples and opening them up to see what was inside. Each stomach from the fish species differed in some way both internally and externally. The most exciting stomach contents that I have found so far came from a Yellow Perch that had eaten five juvenile fish within the last day it was caught. I was able to identify the five juveniles as three White Perch and two Spottail Shiners. There have been various different prey items in the stomachs such as amphipods, chironomids, gastropods and aquatic insects that must now be analyzed. Using the stomach contents from each fish species, I will be able to determine which prey items are the most impactful as well as how location, habitat and fish species differ in diets. My time at the PSC and with OSCAR has been the most exciting summer during my undergraduate years and I hope that in the future I will be able to return and continue to work on related projects.