Very limited research has so far only managed to thoroughly investigate the origins of a few biological invasions in the Arctic marine environment. However we do know based on decades of rigorous scientific research that various different vectors may allow a non-indigenous species (NIS) to gain a foothold in a new marine environment. One of the most prominent vectors often cited in the literature is shipping, and more particularly transportation of species through the ballast tanks or the external surfaces of ships’ hulls (Molnar et al., 2008; Fernandez, 2006; Miller, 2014; Society for General Microbiology, 2008). The global shipping network is growing to a great extent, and lately expanding towards polar waters since shipping through the Arctic allows shorter sailing distances and thus lower costs and shorter shipping times, while creating at the same time new significant environmental threats.

A new, potentially seminal paper by Ware et al (2015) asserts that current ballast water management practices are inadequate in preventing the introduction of NIS in the Arctic marine environment. More particularly the authors use the port of Svalbard as their case study to sketch the risks of ballast-transported NIS establishment. These risks were identified via sampling and identification of transferred propagules through the use of traditional and DNA barcoding techniques. Having taken into account the future climate scenarios and species’ reproduction thresholds related to temperature and salinity, they largely succeed in approaching the underlying risks of invasions enabled by ships’ ballast water in the wider Arctic marine ecosystem (Ware et al., 2015).

Fig 1 Svalbard Port

Fig. 1 Part of Svalbard Port – high-Arctic archipelago

I’ve been employed as a PhD student for more than a year now by University of Southern Denmark, in the city of Esbjerg on the west coast of the Jutland peninsula in southwest Denmark. Esbjerg is a leading Danish port and one of the Nordic’s major intermodal hubs. My PhD is on economic perspectives of Arctic marine invasions, and I have been struggling a bit to collect relevant data that enables me to approach the most highly likely pathways of introductions, so it took me by great surprise to discover the origins of the problem could actually be just a few kilometers away from my office. Ware et al (2015) sampled 7 Carcinus maenas (European Green Crab) megalopae from a single ship that had initially taken its ballast water from the port of Esbjerg, though there was also ballast water exchange that was performed. Carcinus maenas was found by Ware et al (2015) through barcoding in abundance of 10 individuals, from 3 ships.

Fig 2 C maenas

Fig. 2 Projected ecophysiological thresholds for C. maenas by 2050 and 2100 as estimated by Ware et al (2015). Black points indicate known occurrences of the species today, red shows suitable habitat (i.e. critical values above the minimum thresholds) and blue shows unsuitable habitat (i.e. critical values below the critical thresholds).

Carcinus maenas belongs to the highly invasive macroinvertebrates that can reach high abundances and exemplify strong impacts on benthic invertebrates. It has had a rapid expansion in the North-East Pacific over the latest years (de Rivera et al., 2011).

As the authors acknowledge, there is no doubt that besides temperature and salinity (that determined their estimations of the reproductive thresholds), there are numerous other factors influencing the probabilities of colonization of a novel habitat (Ware et al., 2015). Besides a series of other biotic and abiotic factors that may play a discernible role in helping species wriggle their way into the Arctic, anthropogenic ones closely tied to economic incentives such as intense fishing pressure of certain species or mismanagement of fishing resources in some areas can be particularly worrisome in that respect, due to the ecological imbalances they may cause.

One can legitimately argue that the risk of such an introduction and successful establishment should in no case be considered negligible. After all, Arctic Coastal States (Russia and Norway) have already confirmed marine crustaceans’ invasions in their sub-Arctic waters (Barents Sea) and have recognized the threat of further expansion. The Red King Crab Paralithodes camtschaticus is among the most popular examples of deliberately introduced species that has managed to thrive and create a lucrative fishery in the area. It has also brought along numerous ecological consequences, thus presenting a double-edged sword when it comes to its management (Kourantidou et al., 2015). The Snow Crab Chionoecetes opilio, though a more recent crustacean invasion in the Barents Sea, has been unintentionally introduced in the Barents Sea, either though larval drift or ballast water (Kuzmin et al., 1998). It has been spreading at an alarming rate (Bakanev 2014; Sundet 2014) ever since its introduction, with particularly worrisome its northern expansion towards more pristine areas of the High Arctic (Kourantidou et al., 2015). Just as the Snow Crab has managed to find favourable conditions for successful recruitment (Agnalt, A.-L. & Jørstad 2010), so too might other species in the future, bringing new risks, uncertainties and economic consequences over Arctic resources. Studying the crabs and their impacts provides an opportunity to anticipate and defend against damages from increasingly likely future species movements.

Sea ice is definitely becoming less reliable as a permanent natural barrier and thus the impacts of shipping, together with all the other activities that are rapidly developing up north (fishing, tourism, resource extraction etc) arguably elevate the risk of new introductions and thus pose new threats to the economic future of the Arctic (Kourantidou et al., 2015). A lot of scholarly work on an international level has looked into bio-economic patterns of biological invasions, though still very little of the economic literature has dealt with invasions in Arctic ecosystems. I strongly believe it is imperative to improve our understanding of invasive species’ repercussions and for this means we sorely need bio-economic modeling that can delineate the extent of economic consequences, make us more cognizant of the importance of the invasion threat, and eventually help us articulate sound ecosystem management strategies as well as appropriate regulation that will ensure healthy resilient Arctic ecosystems.


Agnalt, A.-L., & Jørstad, K. E. (2010). Recent Trends in Distribution and Abundance of the Snow Crab (Chionoecetes opilio) Population in the Barents Sea. In: G.H. Kruse, G.L. Eckert, R.J. Foy, R.N. Lipcius, B. Sainte-Marie, D.L. Stram, and D. Woodby (eds.). In Biology and Management of Exploited Crab Populations under Climate Change. Alaska Sea Grant, University of Alaska Fairbanks. doi:10.4027/bmecpcc.2010.23

Bakanev, S. (2014). Assessment and Management of Invasive Crab Stocks in the Barents Sea. In Spatial Issues in Arctic Marine Resource Management. Stockholm, Sept 4-6, 2014.

de Rivera, C. E., Steves, B. P., Fofonoff, P. W., Hines, A. H., & Ruiz, G. M. (2011). Potential for high‐latitude marine invasions along western North America. Diversity and Distributions, 17(6), 1198-1209.

Fernandez, L. (2006). Marine shipping trade and invasive species management strategies. International Game Theory Review8(01), 153-168.

Kourantidou, M., Kaiser, B. A., & Fernandez, L. M. (2015). Towards Arctic Resource Governance of Marine Invasive Species. Arctic Yearbook 2015, 175–194.

Kuzmin, S. A., Akhtarin, S. M., & Menis, D. T. (1998). The First Findings of Snow Crab Chionoecetes Opilio (Decapoda, Majidae) in the Barents Sea. Zoologichesky Zhurnal, 77(4): 489–491.

Miller, A. W. (2014). Melting Sea Ice, Accelerated Shipping, and Arctic Invasions. In L. Fernandez, B. Kaiser, & N. Vestergaard (Eds.), Marine Invasive Species in the Arctic (pp. 35–55). Copenhagen: Nordic Council of Ministers.

Molnar, J. L., Gamboa, R. L., Revenga, C., & Spalding, M. D. (2008). Assessing the Global Threat of Invasive Species to Marine Biodiversity. Frontiers in Ecology and the Environment, 6: 485–492. doi:10.1890/070064

Sundet, J. H. (2014). Red King Crab in the Barents Sea. In B. G. Stevens (Ed.), King Crabs of the World: Biology and Fisheries Management (pp. 485–500). Boca Raton, FL: CRC Press (Taylor and Francis).

Ware, C., Berge, J., Jelmert, A., Olsen, S. M., Pellissier, L., Wisz, M., … & Alsos, I. G. (2015). Biological introduction risks from shipping in a warming Arctic. Journal of Applied Ecology.