A non-native invasive fish is spreading on the Swedish west-coast
Populations of the invasive round goby (sv: svartmunnad smörbult, Neogobius melanostomus) are expanding on the Swedish west-coast. Unfortunately, there is not a single success story of eradictation of invasive species in the marine environment, globally. This is true for fish as well as algae. This is of course a huge problem, since invasive species alter habitats, compete with native species and cost millions of dollars to control. Sweden has a long coast line, and the regions along the west-coast and east-coast facing the Baltic Sea are very different. Invasive species in these regions face different environments, and might spread due to different constraints. We are in need of regional knowledge of the ecological processes and patterns that non-native species are involved in, if we are to manage them successfully.
The goal of our project is to give Swedish authourities and the global research community knowledge on how two important ecological processes contribute to the containment of invasive species in the marine environment. These two processes are  top down-control through predation; and  nische space limitation as a consequence of high biodiversity. If these two precoseess do limit the spread of invasice species, healthy populations of predatory fish, as well as thriving, biodiverse fish communities can function as bio-control of non-native species that risk becoming invasive. Conserving the predatory fish and high biodiversity areas would in this case offer added benefit to the resilience of our aquatic environments. These studies are therefore beneficial for understanding what conservation measures and strategies are the most effective and sustainable.
Do predatory fish on the west-coast eat round gobies? - Top down control through predation
Many species of gobies are popular prey for cod, and in the Baltic Sea, it is well known that cod eat the abundant round gobies. But what about the population in the Gothenburg archipelago? Cod are frequent visitors in the Gothenburg habour where round gobies are common. However, nothing is known about the interactions between these two species, and whether or not west-coast cod has learnt to eat round gobies. Other predatory fish, such as eel, might also be important predators that can keep the invasive round gobies in check.
Our goal is to determine how common round goby is as a prey for cod in the Gothenburg archipelago by sampling residual goby DNA in the feces of the cod! By looking for evidence of predation in a non-invasive way, we can save the lives of the cod that have learnt to prey on gobies, and let them continue their presumptive control of the goby population. This is especially important since cod are visual predators that hunt in groups as juveniles, when they can also learn from eachother! Similar proicesses have been observed among groupers feeding on invasive lionfish in the Carribbean.