The fecundity and gonad development cycle of the round goby (Neogobius melanostomus Pallas 1811) from the Gulf of Gdańsk

The round goby (Neogobius melanostomus Pallas 1811) is a non-native species in the Gulf of Gdańsk. The aim of this article is to assess the absolute fecundity and attempt to describe the gonad development cycle of round goby specimens from the Gulf of Gdańsk. The stages of gonad development were classified according to the modified Nikolski (1963) scale for perciformes, which was adapted for the round goby. The sex ratio (female to male) in the population was 3:5. Spawning was most intense during April and July, and there was a pause in June. Fish body size determined fecundity.