Reconstruction of walleye exploitation based on angler diary records and a model of predicted catches

The walleye population in Canadarago Lake, New York, was 81-95% exploited in the 1988 fishing season, the year in which a previous restriction on the length and number of legally harvestable fish was liberalized. Using diary records from a subset of fishermen, growth estimates, and an estimate of the walleye population in the following year, a method is developed to reconstruct the fish population back to the spring of 1988 and thus determine the exploitation rate. The method is based on a model of diary catches that partitions time and fish length into a set of cells and relates predicted catches and population sizes in these cells. The method's sensitivity to the partitioning scheme, the growth estimates, and the diary data is analyzed. The method could be employed in other fish exploitation analyses and demonstrates the use of inexpensive angler-collected data in fisheries management.