Assessment of the bream Abramis brama (cyprinidae) stock of the Nizhnekamsk reservoir with limited data available

Abstract

An analytical assessment of the state of the bream stock in the Nizhnekamsk reservoir was carried out using the method for stocks with limited data – CMSY (Catch-based method). The results obtained indicate sufficient reliability of the use of this model for the bream stock, based on data from official catch statistics of this species. The calculations showed that during the history of exploitation of this population, fishing was carried out mainly in a zone biologically safe for the stock. Since 2017, the catch of bream has increased sharply and currently the fishing volumes are at their maximum values for all the years of the reservoir’s existence. The indicators of current estimates of the stock biomass and fishing mortality exceed their target guidelines and indicate that at the moment the biomass of the bream stock of the Nizhnekamsk reservoir is already in a biologically unsafe zone, and fishing mortality is twice the level of target exploitation.