Long-Range Prediction of the Risk of Extinction Faced by the Pikeperch in the Azov Sea: Was the Prediction Correct?

Abstract

Abstract—In the late 1990s, a high probability of quasi-extinction of the pikeperch population in the Azov Sea within 35 years from 1982 to 2016 was calculated due to increases in salinity. This was based on stochastic simulations with a long-term prediction model of the dynamics of the Azov Sea pikeperch population identified from the 1950−1981 observation data, including stocks, catches, temperatures, and salinities in the Azov Sea. This probabilistic prediction was accurate; the risk event occurred in the 2000s. Since 2005, the abundance of adult pikeperch did not exceed 4 million individuals. Since 2017, the pikeperch catch in the Azov Sea has been completely forbidden. Retrospective validation has demonstrated that the model prediction is in good (qualitative and quantitative) correspondence with the 1982–2018 observation data on dynamics of the pikeperch population. It has also been found that the currently observed rise in annual average sea temperature has a negative impact on fish population dynamics and this phenomenon is no less significant than an increase in salinity. According to a short-range prediction for 2019–2020, the ban on fishing introduced in 2017 is not sufficient to rebuild the stocks of the Azov Sea pikeperch population in the coming years due to existing positive temperature and salinity anomalies.