Influence of the Volume and Composition of Data on the Age Structure of Fish in Catches in the Presence of Gaps in the Series of Observations on Determination of Relative Abundance of Generations

The influence of the volume and composition of data on the age structure on the error in estimating the relative abundance of fish generation using a biostatistical method of loss from fishing in conditions of incomplete initial information was analyzed. On the example of the analysis of control net catches (set nets with a mesh size of 36–90 mm, 31525 specimens) of the bream Abramis brama (L.) from the Kuybyshev Reservoir (2000–2018), it was demonstrated that data on the portion of the generation in catches for 3–4 years (not necessarily adjacent) are sufficient to estimate a relative abundance of the generation with a given average error of 10–15%. In the presence of such information for 5–6 years, the average estimation error was <10%. When using data on the portion of modal age groups in catches (for the bream from the Kuybyshev Reservoir – 2+...6+), the error is minimal. In this case, the average error in determining the relative abundance of generation (when using data for 4–5 years) did not exceed 5%. The determination of the relative abundance of generation on the basis of incomplete data more often provides an underestimate than an overestimate as compared with calculations based on complete initial data.