Information on the state of commercial stocks of the fish population of the Ivankovo reservoir from 1980 to the present is presented. According to our data, the total commercial fish stocks in the Ivankovo reservoir in comparison with the 1980s and 1990s decreased by almost 1,000 tons. Over the past 5 years, they have been in the range of 2245–2808 tons. The closure of industrial fishing in 2007 led not to an increase, but to a decrease in fish stocks, due to a decrease in the rate of their linear and weight growth, deterioration of exterior and commercial qualities. The material damage caused by the closure of industrial fishing at the Ivankovsky reservoir since 2007 has been determined. To determine the material damage caused by the closure of industrial fishing at the Ivankovsky reservoir, retail prices for 21 types of fish were determined. The resulting value for each type of fish was correlated with the volume of fish that was not caught due to the absence of fishing in the period from July 2007 to 2022. Data on catch volumes in the Ivankovo reservoir are taken from the Orders on approval of the total allowable catches and recommended catch of aquatic biological resources in 2007–2022. Over the past 15 years, the possibility of catching almost 7.4 thousand tons of fish has been lost, which in monetary terms is 1,103 million rubles.