This week at the Shedd we were doing fish dissection! We began the lesson talking a bit about fish farms, and how there was sometimes disease in the fish. We then began to look at the fish (Atlantic Striped Bass) externally, taking samples and looking at them under a microscope. We compared the samples to different pictures and descriptions that described different diseases and parasites that might be found. We also measured the pH of water to see if the fish were not in the right pH range (which was about 6.5 to 8), and we measured and weighed the fish to find any abnormalities in size. In our fish we found a sort of skin rot in some of the scales, though this could have been from freezing the fish prior to the lab. After the external examination of scales, fins, and gills (which should have been very red if they were healthy), we cut the fish open after talking briefly about the function of the lateral line, to sense movement/vibration in the water. We inspected different organs, taking out the liver, and again compared them to the given pictures and charts. We also looked at th size of the liver in comparison to that of the other fish. After the internal inspection was over, we popped out the eye so that we could look at the lens. This was the last bit of dissection that we did. We then watched a presentation about fish in the Chicago region. We learned how fish biologists study the populations and habits of the many fish in the region, which tends to be by dragging nets through the water to capture fish to study or by setting traps in deeper water. We learned how some “hotspots” of endangered populations or species were formed. For example, we learned about how a lake had a natural dam made of ice holding it in. When the ice broke, a massive flood changed the land greatly and spread fish in certain places. We also learned about threats to the fish, such as the elimination of small, seemingly unimportant creeks, and irrigation channels that spread cow manure and fertilizer into creeks, resulting in deadly algae or bacterial blooms. We all got to take home a guide to a few fish in the Chicago area, including the American Eel, which comes all the way from the Atlantic, the Burbot, a relative of carp that lives deep in Lake Michigan and tastes wonderful, and the Longnose Dace, a fish chosen by schoolchildren to be Chicago’s city fish. After that, we asked questions about the presentation before the end of class. I think that this was a really valuable lesson and that I learned a lot about fish, especially those nearby.
With Every Drop is a Chicago-based blog, published by CR² team members, that focuses on the biodiversity, ecology, and conservation of marine and freshwater ecosystems.
“Even if you never have the chance to see or touch the ocean, the ocean touches you with every breath you take, every drop of water you drink, every bite you consume. Everyone, everywhere is inextricably connected to and utterly dependent upon the existence of the sea.” – Dr. Sylvia Earle