Mapping silver eel migration routes in the North Sea

Recent developments in tracking technology resulted in the mapping of various marine spawning migration routes of the European eel (Anguilla anguilla). However, migration routes in the North Sea have rarely been studied, despite many large European rivers and hence potential eel growing habitat discharge into the North Sea. In this study, we present the most comprehensive map to date with migration routes by silver European eels in the North Sea and document for the first time successful eel migration through the English Channel. Migration tracks were reconstructed for 42 eels tagged in Belgium and 12 in Germany. Additionally, some eels moved up north to exit the North Sea over the British Isles, confirming the existence of two different routes, even for eels exiting from a single river catchment. Furthermore, we observed a wide range in migration speeds (6.8–45.2 km day−1). We hypothesize that these are likely attributed to water currents, with eels migrating through the English Channel being significantly faster than eels migrating northward.

Hard times for catadromous fish: the case of the European eel (Anguilla anguilla, L. 1758)

Catadromous fish species are very important organisms for their ecological, economical, and cultural value. For its complex life species catadromous fish result in worldwide decline since the beginning of the 20th century. Among the most iconic catadromous species, the European eel Anguilla anguilla L. 1758 has aroused considerable interest since very ancient times. Because, to date, many aspects of their life cycle remain relatively unknown, to implement our knowledge about the main natural and anthropogenic threats to its survivorship and identify possible solutions to preserve it, in this narrative review, we present the state of the knowledge about the life cycle, habitat occupancy, recruitment, and migration patterns of the European eel and about the major threats most likely have contributed to the decline of eels’ populations.

Heterosporis anguillarum. [Descriptions of Fungi and Bacteria].

A description is provided for Heterosporis anguillarum, a parasite of eels. Some information on its morphology, dispersal and transmission and conservation status is given, along with details of its geographical distribution (Asia (Japan, Korea Republic and Taiwan)) and hosts (Anguilla anguilla, A. bicolor pacifica and A. japonica).

ALIEN SPECIES OF FISH HELMINTHS OF BELARUS

The article provides data on the species composition of alien helminth species, which infest introduced fish species in pond fish farms, and also the literature data on natural reservoirs of Belarus. Seven alien helminth species have been revealed in introduced fish in reservoirs of Belarus ( Khawia sinensis Hsü, 1935, Schyzocotyle acheilognathi (Yamaguti, 1934) , Caryophyllaeus fimbriceps Annenkova-Chlopina, 1919, Philometroides cyprini (Ishii, 1931), Dactylogyrus dulkeiti Bychowsky, 1936, Bothriocephalus claviceps (Goeze, 1782) , Anguillicola crassus Kuwahara 1974). All species of helminths excluding the nematode A.crassus and the cestode B.claviceps - parasites of the eels Anguilla anguilla , were introduced to Belarus with the seeding of Cyprinus carpio haematopterus (Linnaeus, 1758) from the Far East. The invasive species of helminths ( K. sinensis, S. acheilognathi, P. cyprini, A. crassus ), which affect fishery by causing the death of farmed fish, are singled out.