According to the Norwegian Environment Agency, Norwegian waters host at a minimum 2320 alien species, almost half of which have been found capable of reproducing and establishing in Norway. These numbers may seem negligible when compared to what is taking place in the eastern part of the world, where the number of harmful species intercepted at China’s ports according to a recent press release look tremendously high and rapidly increasing, however the threat arising from those northern invasions can be of remarkable large scale. Significant damages have so far been reported by crustacean invasions in coastal marine ecosystems all over the world and Scandinavian countries seem to share responsibility for those.
Whilst in Norway the Red King Crab (RKC) (Paralithodes camtschaticus) seems to have garnered considerable attention lately due to both its ecosystem impacts and the profits it generates from the commercial fishery, the appearance of a new crustacean in Sweden, the American lobster, has started becoming quite worrisome. A spread, should one occur, may easily put into peril the native lobster population (European lobster) due to competition, spread of diseases and potential hybridization capable of changing the natives’ genetic characteristics. The Swedish Environmental Ministry has identified more than 30 specimens on the west coast. They reasonably avoid speculation on whether there has been deliberate human intervention for the creation of a new fishery. Anecdotal evidence, at least, indicates human dispersal is a factor but that intentionality is unclear. A recent article in Guardian credits local fishermen with indicating that some of those American lobsters “were still wearing rubber bands round their claws with the exporting company name on the rubber band.” According to the same article, reported introductions in UK waters are believed to be either a result of the deliberate release or of escape of specimens from captivity. The concerns from the other side of the Atlantic (Massachusetts Lobstermen’s Association) regarding Sweden’s request to have the species listed as invasive and encourage a ban on live imports from EU’s side, are loudly being echoed since the lobster export has an annual market value which cannot be overlooked, of $134m.
Both Norway and Sweden have ratified the Ballast Water Management Convention since 2007 and 2009 respectively, which shows the countries’ concerns on the introductions of new species in their waters, but it is worth mentioning that the former has been accused in the past of violating the UN Convention on Biological Diversity for its management of the invasive RKC. RKC’s high commercial value seems to have jeopardized management incentives in the Barents Sea, since there is a growing fishery both on the Norwegian and the Russian side of the species’ spread. Historical management in Norway has shown that economic impacts on local fishermen from RKC’s predation upon previously fished commercial species can easily be managed through allocating crab quotas to those who have been facing bycatch issues.
On the other hand, ecosystem impacts translating into biodiversity loss and thus economic losses entail great difficulty from a management point of view. RKC has been found to have identifiable effects on soft-bottom benthic ecosystems in the Barents Sea, while a little further north a new rapidly growing marine invasion, the Snow Crab, SC (Chionoecetes opilio), is also expected to have impacts upon epibenthic prey species. The existing gap in non-market valuation of such benthic species seems to be hindering economic considerations of the impacts of such invasions while the spread towards international waters, (see SC spread towards loophole) and its impacts there, seem to be receiving scant recognition since management does not directly lie under some country’s responsibility. A typical example, indicating an outright conflict among overlapping fisheries, is the one between SC pots and shrimp trawlers which translates into tangible economic damages.
While SC’s pathway of introduction is still unclear and thus human interference cannot be safely documented, estimates indicate a number 10 times the population of RKC. Impacts of marine invasions cannot be restricted to national coastal zones and thus threats for ecosystem impacts that affect overall social welfare need to be factored, a typical example of which is the potential of spread of the aforementioned crustaceans towards unexplored/undocumented Arctic waters, thus threatening yet undiscovered biodiversity. Crustacean species are also often carrying parasites and commensal species. In the RKC case, indirect evidence indicates that the introduction of RKC is closely associated with increased transmission of trypanosomes, a potential threat for juvenile cod, according to results from trawl surveys along the coast of Finnmark.. Norway has so far experienced significant economic damages from parasites and pathogens such as furunculosis and Gyrodactylus Salaris of up to 4 billion NOK of damage to farmed and wild Atlantic Salmon, according to GIWA’s 2004 Assessment. Significant difficulties lie in the detection of parasites and pathogens while invasive species’ overall impacts can usually be felt years after the initial introduction, when management has not much to offer anymore. A little further east, in Russian waters where RKC was originally intentionally introduced in the 1960s, most of the focus is on maintaining a sustainable fishery for the RKC, with crustacean experts viewing the introduction as a “big present” to Norway from the Soviet Union (2010). Looking at the income they have generated so far, this is an opinion which, despite the research on ecosystem impacts along the years (such as on capelin eggs and lumpsucker as well as competition with other species), seems to have remained the same (2015).
While there is an ongoing growing body of research on the so far ambiguous impacts of some marine invasions, with management interests often being at odds, a pro-active approach that reduces new species introductions seems to be of utmost importance. The realm and scale of economic impacts recorded in the history of biological invasions in marine ecosystems worldwide indicates the need for more pressure on behalf of the global community towards northern states, who have so far been mainly spared from accidental invasions by inhospitable climate conditions and low propagule pressure from low volumes of marine trade. The management of marine invasions in the Arctic will fall primarily under their national jurisdictions. To date, management of existing invasions and threats does not indicate a strong, cohesive precautionary approach. Especially in those cases where newly introduced species are likely to threaten native habitats and commercially or culturally valuable species, applying the basic tenants of precaution and the appropriate cooperative prevention and management schemes seems like an absolute necessity if marine biodiversity and valuable ecosystem services are to be preserved.
Photo Credit: Robert Sisson, National Geographic Creative