Relationship between the age distribution of horse mackerel and the intensity of the glow in the plankton community in the coastal waters of the Heracleian Peninsula (Black Sea)

The Mediterranean horse mackerel Trachurus mediterraneus ponticus is one of the mass fish species in the pelagic of the Black Sea. Studying of the interannual (2010–2015) changes in the intensity of the glow of the hydrobionts, which characterizes the state of the phyto- zooplankton community of the pelagial, was carried out and its relation to the age distribution and growth rates of the horse mackerel inhabiting the coastal waters of the southwestern shelf of the Crimea (the Black Sea) was found. It is shown that the intensity of glow of organisms in winter that characterizes the state of the plankton community of the pelagic determines the features of its development in the subsequent spring and summer periods and, as a consequence, affects the size and weight characteristics and the relative number of age groups of the mackerel in the spring-summer period in the coastal waters of the Heracleian peninsula. It was obtained that changes in the glow of organisms in winter and the relative number of yearlings and two-year-olds in coastal waters are characterized by a negative correlation coefficient, that is, when the intensity of the glow of the plankton community decreases in the winter period, the relative number of yearlings and two-year-olds increases in spring-summer catches of horse mackerel. It is noted that in the years characterized by a higher intensity of glow of organisms in May, the development of horse mackerel is more intense and in these years the individuals of horse mackerel grow well and gain weight. This is confirmed by a rather high correlation coefficient, which for horse mackerel of different age groups is within r = 0,73–0,84. The obtained results can be used in the commercial fishing in predicting the age composition and size and weight characteristics of horse mackerel in spring-summer catches.