Stock assessment of Azov-Black Sea anadromous pontic shad in terms of data lacking (2004-2020

Abstract

The population biomass, fishing mortality dynamics and reference points of the rational exploitation of the Black-Azov sea shad during the period 2004-2020 were evaluated using the JABBA surplus production model in “catch-only” version. IUU estimation and preliminary parametrization by CMSY model was performed to improve assessment accuracy. According to the model output, during the 2004-2020 period shad stock biomass was in interval 1315-1341 t, fishing mortality in range 0,03-0,38. During the implementation and review of model results there was 3 period of shad stock status identified: 2004-2009 – the period of moderate shad stock recovery (from 1315 tons to 3347 tons), 2010-2013 – the period of stable stock status (at the level of 3300-3400 tons), 2014-2020 – the period of moderate reduction of the fishing stock biomass (from 3353 tons to 1791 tons). The moderate reduction of the fishing stock biomass in period 2014-2020 is due to a moderate increase in the level of fishing mortality. Currently, since 2018, there was a moderate trend of increasing fishing mortality above the level of target exploitation, leads to moderate reduction in the stock biomass (in 2020 fells below the target exploitation first time). According to the authors, one of the main reason of human activity, that leads to shad stock biomass reduction is a IUU fisheries. Authors note that there are actions required to annihilate the illegal, unregistered and unreported fisheries of the Black-Azov sea shad.