Use of Underwater Video Surveillance to Monitor a Fish Protection Device at a Thermal Power Plant Water Intake Facility

Introduction. In the near future, the issue of selecting appropriate methods to assess the effectiveness of fish protection devices (FPDs) will continue to be relevant. Previously, the necessary data could only be obtained by ichthyological studies, which involved using specific techniques and equipment. However, the introduction of a new edition of the Code of Rules SP 101.13330.2023 changed the situation and opened up the possibility of using sonar tools to determine the FPDs effectiveness. While there is a lack of public information regarding the specifics and potential of this approach, it is possible that underwater video surveillance may yield similar results to ichthyological (hydroacoustic) methods. This study aims to verify this hypothesis. Materials and Methods. During ichthyological studies at the Zainskaya power plant, fish were captured using nets with mesh sizes of 10, 18, 20, 22, 30, and 70 mm. A Molchanov GR-18 bathometer was used to take phytoplankton samples. Zooplankton samples were collected by the Apstein network. Zoobenthos samples were collected using an automatic DAK-250 dredger. Underwater video surveillance was conducted using a Praktik Murena camera with a resolution of 720 HD (1280´720 pixels), which is equipped with built-in infrared illumination and displays information on a surface monitor. The camera has a wide-angle lens with a 130° viewing angle. Results. A notable advantage of the proposed method, identified in the course of scientific research, concerned the sample size. With video surveillance, it turned out to be 2.25 times larger than with the traditional method. This was because video cameras captured more individuals than the number of fish caught in a net. A larger sample size provided a more statistically significant result. As the amount of data increased, the accuracy of the characteristics of the general population increased, and random error decreased. To determine the FPD efficiency coefficient (EC), the concentration of fish before and after the FPDs, as well as the survival rate of individuals after contact with the FPDs were taken into account. When using the traditional method in 2023, the average EC of the FPDs efficiency at on-shore pumping station No. 3 was 86.9%. Under the same conditions, the new approach proposed by the authors showed a similar average efficiency of 87.3%, with a difference of only 0.46%, which was completely insignificant. The maximum discrepancy was in the spring of 2023, where the indicator of the alternative method was 9.3% higher than the traditional one, while the minimum was noted in autumn at 0.1%. Discussion and Conclusion. So, it was possible to confirm the hypothesis that the underwater video surveillance method is comparable in results with the ichthyological (hydroacoustic) method. However, the new approach is not yet legally recognized and can only be used as an additional tool. Firstly, video surveillance can help to determine whether ichthyological studies are necessary. Secondly, water intake operators can use the experimental method in between ichthyological surveys to obtain operational data on the effectiveness of FPDs.