Minnesota water authorities caught and removed more than 5,000 pounds of goldfish from Big Woods and McKnight Lakes in November. The enormous catch is part of a multi-year research project that has been running since 2019. Even then, Big Woods Lake had the largest population density of goldfish that the researchers had ever seen. Experts estimate the population to be between 300,000 and 500,000 specimens spread across five lakes.
Minnesota Water Board: The Goldfish Must Go!
Without natural predators, goldfish released illegally can reproduce very quickly. Due to their robustness and long lifespan, the invasive goldies pose a threat to the ecosystem.
Goldfish also endure extremely cold temperatures and can cope with very low oxygen levels. Compared to other fish, goldfish can get by without oxygen for some time before they perish. During this time they maintain their metabolism only with the intake of sugar; alcohol is the end product of the metabolism. They even survive the freezing over of shallower waters. They live up to 25 years – a long time to churn up sediment and compete for food with native species.
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Pike in the land of milk and honey
When the goldfish plague was discovered by the Minnesota water authority in 2019, the officials first put pike into the corresponding waters. To do this, they equipped 500 goldfish with tracking devices to record the movement of the invasive species. As early as 2020, the water authority removed over 100,000 goldfish from the lakes. When asked by a user on Facebook, the officials said that the fish they had taken should be buried and used as compost. Another user asked why a large part of the goldfish no longer have the typical golden color. The organization then stated that the goldfish would lose their color over the generations because gray hues were more useful in the environment.
Nets and fish traps were used for extraction, as well as catching with electric fish devices. When fishing, there was only a bycatch of just two percent of native fish, which were released immediately.
Quelle: Field and Stream
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