Sub-challenge: For each river bordering the sea basin, a time series of annual inputs to sea of eels (both inwards and outwards).

As no specifications have been made regarding the species of eel, it has been decided to look at freshwater occurring true eels or eels of the Anguilla genus. Of the 16 Anguilla species, eleven are considered tropical and five are considered temperate (Arai, 2016). Of the five temperate species only two species reach the study area: European eel or Atlantic Eel (Anguilla anguilla) and American Eel (Anguilla rostrata) (Dekker, 2003; Solomon & Ahmed, 2016).

European eel or Atlantic Eel (Anguilla anguilla) has a complex life-cycle which included long-distance migration from fresh-water or coastal habitats to the spawning grounds in the Sargasso Sea but it does not have a major distribution in the Arctic Area (Figure 1, Fishbase and Wysujack et al. 2015).

native habitat European eel
Figure 1: Native habitat of European Eel, source: Fishbase.org.

According to Karamushko (2008), the European eel is the only catadromous species in the Barents Sea and has only been recorded as solitary captures. Dekker (2003) reports a gradual decline to the North, with Iceland as the outer fringe of distribution. According to Mecklenbug et al. (2011) the European eel reaches the White Sea. However, no datasets on the in- or outflow of eel in this area have been found. Davidsen et al. (2011) confirm the lack of published literature on the migratory behavior of European eel in northern areas. Davidsen et al. (2011) performed a study on migratory eel in the Alta Fjord, Northern Noway. Figure 2 shows the number of seawards migrating eels between 2000 and 2010.

numbers seawards migrating eel
Figure 2: Number of seawards migrating eel in the Alta Fjord from 2000 to 2010 (Davidsen et al. 2011).

American Eel (Anguilla rostrata) is also not found further north than the south of Greenland (it has been recorded in Greenland in 2005 (Møller et al. 2010) and in 1973-1975 (Boëtius, 1985)) (Figure 3) and no information on the in-or outflow in the major Arctic river basins was found.

native habitat American eel
Figure 3: Native habitat of American Eel, source: Fishbase.org.

No other true eels live in the Arctic Area. However, a species which could be compared to both eel and salmon is the Arctic Lamprey (Lethenteron camtschaticum), an anadromous fish with an eel-like appearance. The distribution is almost circumpolar (ICES, 2016), as can be seen in the figure below. However, data on this species’ in- and outflow is scarce. In Alaska, the Arctic Lamprey is quite abundant, however no specific data on recruitment or migration is available (ADFG, Arctic Lamprey).

native habitat Arctic lamprey
Figure 17: Native habitat of Arctic Lamprey, source: Fishbase.org.

Conclusions and recommendations:
There are no major eel populations in the Arctic area, but smaller stocks are present in the Northern territories. However, no datasources or datasets with eel abundances on the chosen Arctic rivers were found. Due to climate change the eel population might spread further into the Arctic area, where potential habitats are available. As eel is in many countries a commercial species, a better understanding of the distribution and populations of eel in the Arctic could prove useful. Monitoring of rivers can be quite time consuming and intensive, however, we would recommend using more automated methods than catch and release such as camera traps, laser counts and sound or echo location.