Describing physical features of larval lake whitefish and cisco in Lake Michigan
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The Great Lakes at one time were populated with many coregonine species. Over the past few decades commercial fishing, invasive species, and habitat loss have decreased coregonine species populations. Recently, lake whitefish have been experiencing a decline in population in Lake Michigan. Both species have similar spawn times, similar hatch times, and have the same diet. In this study, the two species measured were Cisco (Coregonus artedi) and Lake Whitefish (Coregonus clupeaformis). Both fish are coregonids, a genus of fish in the Salmonidae family. 162 larvae samples were imaged under a light microscope and measured using Image J software. All samples were collected starting in late May and ended in the last week of June. All statistical functions were performed using R Studio software. Two models were used to incorporate 12 variables that tested whether different physical features were more significant than others and whether there was a significant difference between ethanol images and live images. The classification tree comparing species observed Cisco with 34% accuracy and lake whitefish with 95% accuracy. The most significant species variable was pupil diameter. Preserved images were observed with 73% accuracy and live images with 70% accuracy. The most significant variable for the classification tree comparing image type was opercle length. Based on the data, it is possible that the lake whitefish population is recovering.