Round goby in net
The round goby (Neogobius melanostomus) is an invasive alien species that spreads rapidly and is well established in several places along the Swedish coast.
Photo: Leon Green

The abundance of the invasive round goby is examined by e-DNA


An invasive fish called round goby is rapidly spreading along the Swedish west coast. Can this species' distribution be limited by predatory fish such as cod and eel? Leon Green, researcher at the University of Gothenburg, will investigate this in a new research project.

Leon Green portrait
Leon Green, a researcher at the Department of Biology and Environmental Science, defended his dissertation in 2020 with a dissertation on how the round gobys can breed in different environments.

Leon Green, researcher at the Department of Biology and Environmental Science, receives SEK 3.6 million in support from the research council Formas  and Swedish Environmental Protection Agency for the project "Predators and biodiversity as a biological control of the invasive round goby on the Swedish west coast". 

What are you investigating in this project?

“I will investigate how the occurrence and density of round gobies are affected by other fishes on the Swedish west coast. Predatory fishes such as cod and eel can be important players when it comes to limiting the spread of round goby. Other fish species can also compete with the round goby for food and habitat, making it harder for it to establish itself. In short, we will see if the round goby can be limited by high biodiversity and predatory fish.”

How will you do that?

"The role of predatory fish will be investigated by developing new e-DNA methods, where we plan to work non-invasively. Instead of killing the predatory fish and looking through their stomachs for round gobies, we will let the predatory fish defecate their leftover food and investigate whether there are traces of round goby DNA. In this way, we can both keep the predatory fish that have learned to eat round gobies, and still get valuable data"

"The biodiversity part of the project will focus on the fish community, and there we will use underwater cameras to get an insight into what the species composition looks like in areas with more or fewer round gobies. The videos will then be analyzed through a public online platform, where citizen researchers will be able to participate in the project. The goal is also that the videos can be good tools for pupils, students and perhaps even adult divers who want to learn to see the difference between our most common Swedish fish, and that the data will also be made public."

What do you hope the project will lead to?

"I hope that it leads to an increased understanding of how biodiversity and predators can limit the spread of invasive species. If it turns out that the round goby is limited in ecosystems with high species richness and larger populations of predatory fish, we can get increased positive effects by managing these ecosystems well. Resources invested in promoting biodiversity and predatory fish could then give us more than "just" living seas - that is living seas that are also resistant to invasions from alien species."

By: Karl-Johan Nylén

Facts: Round Goby

The round goby (Neogobius melanostomus) is a fish species originating from the Caspian Sea and the Black Sea and it probably arrived by ballast water to the Baltic Sea. The round goby is an invasive species with fast reproduction and high tolerance for varying environmental conditions. There is a risk that it might compete with other native bottom dwelling species like black goby, eelpout and flounder.