Round Goby: A fish with a funny name threatens to destroy the aquafauna of the Great Lakes and poison people. What's wrong with her? (7 photos)

His hunger is insatiable and he is a threat to biodiversity. The round goby is a small fish with a funny name, which combines an unbridled desire to fill its bottomless stomach with any, even toxic, muck and with the zeal of a kamikaze to continue its race. And therefore their army is marching steadily towards dominance over the European seas and American lakes.





An inconspicuous body up to 30 cm long is decorated with a black mark on the dorsal fin, promising an imminent attack. In the reservoirs where this unexpected guest appears, troubled times begin. The fact is that bulls are extremely unpretentious. So much so that they can live in both salt and fresh water. If previously the species lived only in the waters of the Caspian and Black Sea, now the fish have reached all the way to America! To the Great Lakes!



By the way, another noticeable difference between the round timber is the fused pelvic fin, which plays the role of a suction cup.

It would seem, what can a small fish that doesn’t even have a swim bladder do? However, in the depths of the gastrointestinal tract of this little one lies a black hole: his wild gluttony is combined with absolute indiscriminateness in food - everything that fits into his mouth is recycled. The aggressive horde successfully conquers new territories, after which a complete “wasteland” remains.





The distribution includes the goby's neighbors - bottom inhabitants: mollusks - zebra mussels and mussels - larvae, eggs and juveniles of other fish. The gluttony of bulls hits the latter especially hard. Doubly so in the waters of the Great Lakes. The introduced round timber devours endemic fish species at the juvenile stage, reducing their already small population.



But the problems don't end there. We all know that mollusks actively filter water, accumulating all the nastiness of reservoirs in their tissues. But the bulls are not aware of this, and therefore, when they eat zebra mussels, they transfer the filth they have collected into themselves without a bit of suspicion. Considering the huge number of bivalves devoured, the body of the round logs turns into a huge dump of toxic substances. It is passed along food chains to larger predators and ultimately ends up on the human table.



The main secret of the prosperity of round timber lies in their hard work and dedication to the production of their own kind. The stamping of new bulls begins in April and continues in large series every three weeks until September - this is much more common than the neighbors in the reservoir.



The male, having dug a nest in the ground, covers the walls with secretions. Before entering such a cave, a queue of females forms. The ladies, whom the man lures into the nest one by one, cover the walls with eggs in regular rows: they make sure that their clutches do not mix with each other.



The male, having received a nest full of eggs, fertilizes it and remains to guard his babies. After two and a half weeks, five thousand fry are born, and their emaciated father dies with a sense of accomplishment. Thus, in one season, the army of bulls is replenished with tens of thousands of young and independent warriors, ready to live for the sake of their population for four long years.