The human dimensions of biological invasions – involving stakeholders in addressing invasive species

Can the knowledge and experience of recreational anglers in Iceland help us understand how far the invasive flounder has spread in the country?

Guest blog post by Theresa Henke

For centuries, all kinds of species have been transported by humans around the globe, allowing them to cross the boundaries of their native range and settle in new ecosystems. Over the past decades the numbers of these introduced species and the impacts they cause have been continuously increasing. Biological invasions nowadays represent one of the biggest threats to biodiversity worldwide.

Humans are and have always been an essential part of biological invasions and in order to fully understand the issue and how to tackle it, we need to understand and include the human dimensions in our research.

My research on European flounder in Iceland began in 2017 when I was writing my Master’s thesis. The flounder is a flatfish species that had been officially documented in the country since 1999 but not much was known on its impacts. In my thesis I looked at the flounder through ecological lenses, trying to identify how the presence of the flounder affects other species. Living in a small community in the Westfjords of Iceland during this time, I got to meet many local people who shared their personal stories, experiences and knowledge with me in every-day conversations. I truly enjoyed these conversations and learning about the species I study from different perspectives beyond the academic settings. These exchanges sparked my interest in exploring the human dimensions of biological invasions and, looking back, have really shaped my academic path going forward.

Theresa Henke holding a flounder.

In our recently published NeoBiota study “Have you seen this fish? – Important contribution of stakeholder observations in documenting the distribution and spread of an alien fish species in Iceland” we wanted to explore how the knowledge and experience of recreational anglers in Iceland can help us understand how far the flounder has spread in Iceland. The flounder in Iceland had only received little scientific interest before and the available information was limited and scattered between different institutions and scientists. Recreational anglers, on the other hand, who chase after native salmon, trout, and char in the Icelandic rivers and lakes, often encounter the flounder.

A net full of flounder.

In 2019, we asked anglers in Iceland to take part in an online survey, where we asked them different questions about the flounder, including where in Iceland they have seen or caught it. We then compared locations named by anglers to the locations that were available from different databases of the Marine and Freshwater Research Institute of Iceland. The locations we received included data collected during scientific surveys and research projects done by the institute as well as observations that were reported to the institute by the public (mostly recreational anglers and commercial fishermen).

Our goal was to evaluate whether observations made by stakeholders, in this case the recreational angling community in Iceland, could be a good source of additional information for monitoring of an alien fish species. Collecting information on the distribution and spread of an alien species is a very important step in addressing biological invasions but is often underdeveloped because not enough resources (i.e. money, time, scientists…) are made available.

Theresa Henke holding a 43-cm flounder in Eyjafjörður.

We have shown that neither source offers a perfect solution to the monitoring of the flounder in Iceland. But we show that each of the sources has their own advantages and disadvantages and by combining them, we are able to get a much clearer picture of where in Iceland the flounder currently occurs and how fast it spread in the early years. Information that was shared by stakeholders, whether it was in our study or to the databases of the Marine and Freshwater Research Institute, played a big role in better understanding the flounder in Iceland.  

The interactions with the recreational angling community in Iceland during my PhD have taught me a lot about the flounder in Iceland but even more about my own approach to science. I think as scientists, we should more often take a step outside of our academic bubble and take a look at the issue we are studying from the perspectives of the public and other stakeholders. In the case of biological invasions, we can learn a lot from those who are directly confronted by an invasive species, regardless of whether they have a scientific degree or not.

Research article:

Henke T, Bárðarson H, Thorlacius M, Ólafsdóttir GA (2025) Have you seen this fish? Important contribution of stakeholder observations in documenting the distribution and spread of an alien fish species in Iceland. NeoBiota 97: 67-90. https://doi.org/10.3897/neobiota.97.132365

Undergraduate student takes to Twitter to expose illegal release of alien fish in Japan

Posing a significant threat to the native biodiversity in Japan, specifically that of threatened aquatic insects, some alien fishes, such as the bluegill, have become the reason for strict prohibitions. All activities potentially capable of introducing the species into the wild are currently punishable by either a fine of up to 3 million yen for a person (100 million yen for corporations), or a prison sentence of up to 3 years.

Recently, ten years after the law has been adopted, illegal release of bluegill fish has been reported for the first time with the help of a post on Twitter from Akinori Teramura, undergraduate student at the Tokyo University of Marine Science and Technology and second author of the present study. The case is reported and discussed by him and two scientists, affiliated with Kanagawa Prefectural Museum of Natural History, Japan, in the open-access journal ZooKeys.

In June 2015, Akinori Teramura tweeted two photographs of the invasive bluegill fish, both adults and juveniles, along with two young goldfish, which do not belong to the local fauna, either. In his post he identified the species and shared his surprise at the irresponsibility of the people who had released the fish. When lead author Dr Yusuke Miyazaki saw the tweet, he signalled his colleagues with the idea to publish the information as a scientific report.

The student found them in an outdoor public pool in Yokohama city, Japan, while it was being cleaned before being opened ahead of the summer. Usually, these facilities are closed to the public during the colder seasons and it is then when native aquatic insect species, such as dragonflies and diving beetles, find spawning and nursery habitats in them. Curiously enough, though, the pool had been isolated from natural waters since its construction.

7577_ZK_Data-mining and Twitter img3

Therefore, the researchers conclude that the alien fishes have most likely been released from an aquarium from a local shop or an aquarist who no longer wanted them. However, the authors note that according to the law, keeping bluegill fish in a home aquarium is illegal as well.

“Our report demonstrates an example of web data mining in the discipline of Citizen Science,” say the authors. “Web data mining has been rapidly developing over recent years, and its potential continues to expand.”

“Community awareness of this issue needs to be improved, and widespread reporting of cases such as this one will help,” they conclude.

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Original source:

 

Miyazaki Y, Teramura A, Senou H (2016) Biodiversity data mining from Argus-eyed citizens: the first illegal introduction record of Lepomis macrochirus macrochirus Rafinesque, 1819 in Japan based on Twitter information. ZooKeys 569: 123-133. doi: 10.3897/zookeys.569.7577