Spatial and temporal analysis on sprat (Sprattus sprattus L.) surveys catch per unit effort and catch per unit area from Bulgarian marine zone

Abstract. Sprat (Sprattus sprattus L.) is a keynote species in the Black Sea, and stock dynamics
is highly affected by the fisheries and environmental conditions. Another important feature of the
species is cyclic nature of its spawning stock biomass and recruitment. Thus, seasonal fishery independent
surveys are crucial for stock condition evaluation and managerial decisions for sustainable
exploitation. Sprat surveys under DCF (DCR199/2000 EC) were conducted in spring 2007–2010
and autumn 2015–2018. The present paper considers the use of GIS application which is frequently
used as a supplementary tool for spatial analyses of fisheries activities including commercial fishing,
impacts of IUU fishing, by-catch, unintentional catch of protected species, etc. Analyses are
to support the follow-up assessment and decision-making process. Principal component analysis
(PCA) is applied to explain biomass variability within the stratified survey area as well as population
distribution analysis, based on the survey results. High variability was identified in both parameters
Catch per unit area (CPUA) and Catch per unit effort (CPUE) within different seasons and years.
PCA and stock distribution analysis results are explained in the view of stock biomass distribution
within the stratified survey area.