Hi, my name is Reid Griffin, and I’m a 2023 Hollings Scholar. This summer, I studied the age and growth structures of smallmouth bass (Micropterus dolomieu) within the Weldon Headpond in Maine. My data contributed to a larger study on smallmouth bass predation of the endangered Atlantic salmon.
Purpose of the study
Atlantic salmon (Salmo salar) are endangered in the United States and have only one remaining wild U.S. population. The Weldon headpond is one of the most dangerous sites for smolts, or young salmon, in this population. One culprit behind higher death rates at Weldon Headpond may be predation by smallmouth bass. My study focused on understanding age and growth rates of smallmouth bass, which can help us better estimate predation in this area.
My project
We investigated smallmouth bass age and growth rates using a small calcium carbonate structure in their inner ear called otoliths. As the fish grows, so does the otolith. The otolith grows in a way that creates bands, similar to tree rings. You can count the bands to estimate the yearly age of a fish. In addition to that, the distance between bands also can tell us how much a fish has grown in that year.
We extracted otoliths from roughly 50 smallmouth bass angled from the Weldon Headpond. To see the bands, you need to look at a thin cross section of the otolith under a microscope. We prepared the otoliths for imaging by cleaning them, cutting a thin cross section, and then polishing them using sandpaper to a very thin sliver. Once we counted and measured the bands, we estimated the fish’s average maximum size and the growth.
Results
Once this was all done, we provided the data for use in a bioenergetics model. From the model, we can determine if smallmouth bass are statistically likely to be a major force behind the high Atlantic salmon death rates seen in the Weldon Headpond.
Reid Griffin, 2023 Hollings scholar
Reid is a class of 2023 Hollings scholar and a Marine Biology major at the University of Alaska Southeast.
