Thus, the genes encoding for the cytokeratin 1 and keratin 12 were found to be overexpressed in migratory eels.
The visit is part of a wider campaign to draw attention to river barriers which stop the migratory European eel from reaching its home waters.
Schweid is rightly awed by the implacable migratory instincts of eels, which will swim great distances upstream and, if need be, squirm across dry land to find the right body of water.
The group is devising a recovery plan that includes finding ways to unblock the eel's migratory routes.
Osteological analysis of fish bones, through their stable isotope signatures, indicates that early medieval sites are dominated by the remains of freshwater and migratory species such as eel and salmon, while later settlements reveal that the consumption of marine species such as herring, cod, hake, saithe and ling was widespread.
For generations, the arrival of migratory so-called European eels used to be anxiously awaited at this time of year by fishermen on the Severn and Wye tidal rivers.
Migratory silver-phase American eels (Anguilla rostrata) tested during dark conditions readily located, entered, and passed through the bypass; initial avoidance rates (eels approaching but not entering the bypass entrance) were lower at higher entrance velocities.
Paul Greenberg ends his review of "Eels" by saying that the author, James Prosek, "passes on the truth that the often disdained eel, like all migratory fish, is vital and mysterious and worthy of our full effort to bring it back" ("Slither Room," Oct. 24).
Because sea turtles use a similar magnetic map, the researchers speculate that many migratory marine animals, such as eels, sharks, and seals, may also navigate using magnetic fields.
But environmentalists fear that by blocking the Severn estuary completely, the barrage would destroy vast areas of mudflats and mashes, which are vital feeding grounds for tens of thousands of wading birds, and prevent migratory fish such as salmon and eels from ascending rivers to spawn.
