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First report on intersex in invasive round goby Neogobius melanostomus from the Baltic Sea (Gulf of Gdańsk, Poland)

Guellard T., Sokołowska E., Arciszewski B.

Oceanologia

2015

No. 57 (1)

102--106

This study is the first to report the presence of intersex in invasive round goby Neogobius melanostomus inhabiting the Baltic Sea. The discovery was made in the area of two harbours of the Gulf of Gdańsk (Poland). Macro- and microscopic male gonad analysis revealed the presence of female gametes in testes (testis-ova) of single specimens. In addition, a female-like urogenital papilla was observed in one of the intersex fish. These findings might be due to the exposure to estrogenic endocrine disrupting compounds (EDCs) however the occurrence of single intersex individuals as a baseline level in investigated population is also possible. In the future, more comprehensive research in the other areas of the Gulf of Gdańsk needs to be carried out in order to determine the extent and to better understand the cause of the observed phenomenon.

Study of swimbladder morphometry of baltic herring and sprat (development of measurement methodology)

Idczak J., Gorska N., Arciszewski B.

Hydroacoustics

2011

Vol. 14

61-68

Effective management of Baltic clupeids, which are valuable commercially and ecologically, requires the biomass control. The acoustical techniques are recognized as effective in fish stock assessment. The study of Baltic herring and sprat individual backscattering characteristics is required for the accurate biomass estimation using acoustical techniques. The previous measurements demonstrated significant dependence of the backscattering properties of Baltic clupeids on their geographical location. For southern Baltic Sea the properties are not recognized sufficiently yet. Accounting for that fish swimbladder morphometry effectively impacts on the backscattering, it is important to study the morphometry of southern Baltic herring and sprat. It motivated the paper study. The paper is addressed to the development of the methodology of the analysis of the accurate shape of the swimbladder. The way of the fish catch, transport and storage, the X-ray irradiation and the X-ray image analysis was developed.