Archives at the Institute for Fisheries Research (IFR) hold records of thousands of lake surveys from the University of Michigan and Michigan Department of Natural Resources. The records contained in this dataset are jpeg images of the index card records from the IFR surveys. Images include the front of the card and when available, the back of a card. and Fish Growth Cards report information on the age and length of fishes captured in lake surveys. The age of a fish was determined by counting annual rings on hard structures including scales, spines and otoliths (fish ear bones).
