Age and growth of the round goby Neogobius melanostomus in the Gulf of Gdańsk several years after invasion. Is the Baltic Sea a new Promised Land?


  • E. Sokołowska,

    1. Department of Genetics and Marine Biotechnology, Institute of Oceanology of the Polish Academy of Sciences, ul. Powstańców Warszawy 55, Sopot 81-712, Poland
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  • D. P. Fey

    Corresponding author
    1. Department of Fisheries Oceanography and Marine Ecology, Sea Fisheries Institute in Gdynia, ul. Kołła̧taja 1, 81-332 Gdynia, Poland
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The ages of 8 to 23·5 cm total length (LT) round goby Neogobius melanostomus collected monthly during 2006 and 2007 in the Gulf of Gdańsk (Baltic Sea) ranged from 2 to 6 years, with age class 4+ years dominant. Males were larger at age than females. The fastest growth occurred in the first 2 years of life in both sexes. Females were heavier at a given LT than males, but only for fish > c. 15 cm. A strong relationship between N. melanostomus otolith size and fish size was found, with no difference between males and females, and a significant relationship between fish growth rate and otolith growth rate, which enabled backcalculation of growth rates. Marginal increment width analysis confirmed the periodicity of annual ring formation in otoliths and showed that the most intense opaque zone formation occurs in July to August, while hyaline zone formation starts as early as September to October. It was concluded that the N. melanostomus that have colonized the southern Baltic Sea exhibit the largest size and longest life span ever recorded for this species.