The state of commercial stocks of common carp (Cyprinus carpio Linnaeus, 1758), bream Abramis brama Linnaeus, 1758), roach (Rutilus rutilus Linnaeus, 1758) and pikeperch (Sander lucioperca Linnaeus, 1758) in the Dniester lagoon in 2000-2019

Abstract

Purpose. Assessment of the commercial stocks of common carp Cyprinus carpio Linnaeus, 1758, bream Abramis brama (Linnaeus, 1758), roach Rutilus rutilus (Linnaeus, 1758) and pikeperch Sander lucioperca (Linnaeus, 1758) in the Dniester Lagoon in 2000-2019. Methodology. Sampling was performed in the Dniester Lagoon using standard ichthyological methods “Metodiki zboru і obrobki іhtіologіchnih і gіdrobіologіchnih materіalіv z metoju viznachennja lіmіtіv promislovogo viluchennja rib z velikih vodoshovishh і limanіv Ukraїny» and «Metodicheskie ukazanija po ocenke chislennosti ryb v presnovodnyh vodoemah». The fish stocks in the Dniester lagoon were assessed using the BSM (Bayesian State-space Model) module. The main advantage of BSM compared to other implementations of surplus production models is the focus on informative priors and the acceptance of short and incomplete (fragmented) catch-per-unit-of-effort (CPUE) data. Findings. The paper presents the current state of the main commercial fish species, the results of stock assessment of the common carp, bream, roach and pike perch and their commercial exploitation in the Dniester Lagoon. The catch of common carp in the Dniester Lagoon has a tendency to increase in 2018-2019. The state of its stock is considered relatively stable and depends on artificial restocking. The forecast for the allowable catch of the common carp should not exceed 40 tons. The exploitation of bream stock was optimal within recent years. The stock of this species is in a relatively satisfactory condition. The bream catches should not exceed 120-150 tons per year. The commercial part of the roach population was exploited at a level close to optimal in recent years. The forecast of its allowable catch was determined as 45 tons. The pikeperch stock of the Dniester Lagoon is in extremely poor condition. The forecast for the allowable catch of pikeperch should not exceed 5 tons. Originality. The presented research paper is an attempt of using the BSM for assessing the current state of the commercial stocks of the common carp, bream, roach and pikeperch in the Dniester Lagoon. Practical value. This publication provides recommended forecasts of the allowable catch for optimal exploitation of the common carp, bream, roach, and pikeperch stocks of the Dniester Lagoon.

Keywords

• dniester lagoon
• stock assessment
• level of commercial exploitation
• forecast of allowable catch