Non-indigenous or alien species need to be appreciated for their potential benefits and not just the negative impacts they can have on the environment, according to new research.
In recent decades, there have been numerous examples of non-indigenous species (NIS) establishing a foothold and then causing harm in new environments. Meanwhile, others have had benefits for fisheries or replaced lost ecological functions.
Stopping the spread of such species is virtually impossible, so a new study - led by the University of Plymouth and the Marine and Environmental Research (MER) Lab in Cyprus - is calling for a complete rethink of how they are considered in the future.
Focused on the Mediterranean, the most 'invaded' sea on Earth, the research highlights species - including lionfish, clams, barracuda, rabbitfish and jellyfish - that have become resident in the region as a result of factors such as the changing climate or human introduction.
To try and address such issues, the study proposes a cost-benefit analysis which will guide whether NIS should be managed in a sustainable or unsustainable way.
Where non-indigenous species are known to have positive effects on the environment and marine economies, a series of policy reforms are proposed.
However, where there are no perceived benefits, it proposes legislation to actively promote commercial over-fishing and the creation of radical NIS-specific licences for recreational fishers. One example of such a species is the lionfish (Pterois miles), first seen in the Mediterranean Sea in 2012 but now thriving and well-established across southern Europe and having a marked impact on other native species and the wider environment.
The study also recommends investment in the market and valorisation of NIS products, the development of novel products, and fishery-related tourism.
It also highlights the importance of investing in natural-based solutions such as the protection of native predators, the enhancement of marine protected areas (MPAs), and allowing SCUBA divers to remove invasive species from MPAs.
The application of the proposed reforms would turn NIS into a source of income and nutrition, and adhere to United Nations Sustainable Development Goal 14, which calls for the conservation and sustainable use of the oceans, seas, and marine resources for sustainable development.
The researchers behind the study are among the collaborators on the four-year, €1.6million RELIONMED project - funded by the European Union - which aims to assess the history of the lionfish invasion in Cyprus, and identify ways to minimise its future impact.
Periklis Kleitou, Research Assistant on the RELIONMED project and lead author on the study, said: "The Mediterranean is heavily over-exploited. But it is unwise to perceive all the effects of non-indigenous species in the region as negative. Some species have been established in the basin for decades playing a major role in ecosystem and fisheries balance. In some parts of the eastern Mediterranean, they might account for over half the fishery catches in some areas, but the solutions we propose would create an ecosystem-based framework to promote fishery sustainability in the region."
Co-author Dr Sian Rees, Associate Professor of Social-Ecological Systems at the University of Plymouth, added: "Transformative ocean management demands that we think beyond our current norms and challenge dominant narratives. This research connects - for the first time - the roles that non-indigenous species play in driving down levels of biodiversity and at the same time providing opportunities for fishing (food production). What we are proposing is a new governance perspective that firmly links fisheries management with conservation and investment strategies. This research is set to change how NIS are managed in the Mediterranean and provide long term benefit for society."