Spread of alien (non-indigenous) fish species Neogobius melanostomus in the Gulf of Gdansk (south Baltic)

Abstract

The round goby (Neogobius melanostomus) was first noticed in the Gulf of Gdansk in 1990. This PontoCaspian fish was most likely introduced to the Baltic environment from ships' ballast water. During the first years of invasion, slow population growth was observed in the initially colonized regions. From 1994, round goby gradually spread in all shallow water zones of the Gulf of Gdansk. The area occupied by the population and the number of fish grew rapidly. By the end of the nineties, round goby became a dominant fish in shallow waters of the western part of the Gulf of Gdansk, where the fish used all solid substrates on the bottom, including concrete piers, big stones or even dumped waste for spawning and refuge. The presence of round goby in the Vistula Lagoon and shallow waters near Rugia (Western Baltic) was noticed for the first time in 1999. The present state, size and condition of the round goby population in the Gulf of Gdansk led us to predict a continual spread of this species into new regions of the Baltic. In addition, the population of round goby is so large that the species has started playing a part in commercial fishing in the Gulf of Gdansk.

Infection rates and prevalence of metazoan parasites of the non-native round goby (Neogobius melanostomus) in the Baltic Sea

“…This reflects a general change in dominant habitats from southern to northern Baltic Sea. The locations in Lithuania, Estonia and Finland were also close to artificial structures such as piers or built embankments, which has been noted as the round gobies preferred habitat as they provide suitable nesting sites and shelter (MacInnis & Corkum, 2000;Sapota & Skora, 2005;Ojaveer, 2006). The populations differ as to the time of invasion: the Lithuanian population around Klaipeda was discovered in 2002 (Sapota, 2011) and the population in Muuga, Estonia (Gulf of Finland) was discovered two years later in 2004 (Ojaveer, 2006).…”

“…Many researchers have also suggested the lack of natural enemies as a major contributing factor (Sapota & Skora, 2005;Kvach & Skóra, 2006;Kvach & Stepien, 2008;Gendron et al, 2012). Parasites are important biological regulators and occur as an inherent part of any biological community (e.g.…”

“…The round goby was most probably transported to the Gulf of Gdansk in ballast water as eggs or larvae (Sapota & Skora, 2005). It is not known whether the source population is from the Black, Azov or Caspian Sea and whether it arrived via the inland river systems of Don/Volga or Dnieper-Vistula, but the species was most likely transported to the Baltic with the ballast water of vessels (Sapota, 2004).…”

Modification in the nest guarding strategy — one of the reasons of the round goby (Neogobius melanostomus) invasion success in the Gulf of Gdańsk?

“…Actually, the round goby is one of the dominant fish species in the shallow, inshore waters of the area (Corkum et al 2004, Sapota 2004, Sapota and Skóra 2005, Wandzel 2000.…”

“…Gobies were of small importance during the first few years of the invasion, Copyright© of Dept. of Oceanography and Geography, University of Gdańsk, Poland www.oandhs.ocean.ug.edu.pl but soon they became the dominant fish of the shallow-water fish community (Corkum et al 2004, Sapota 2004, Sapota and Skóra 2005, Wandzel 2000. The invasion in this area involves a number of different species and a stable and complex ecosystem.…”