Every spring, residents of the tiny Danish island of Anholt, midway between Denmark and Sweden, eagerly await the arrival of the harbor seals that breed on the island's sandy beaches. This year, however, they have been witnesses to a mysterious season of death. So far, more than 150 dead and dying seals and their prematurely born pups have washed ashore; in the past few weeks, Lighthouse Keeper Einar Boisen and others have been picking up as many as 17 dead seals a day. Says Boisen: "We've started calling ourselves the death patrol."
The harvest of corpses has raised fears in countries abutting the North Sea that all the seal pups in the region could be wiped out. The toll to date: at least 450 adults and pups in Denmark and an additional 50 in West Germany, out of a total population of 10,000 to 15,000 in the region. Many scientists strongly suspect that acute pollution of the North Sea is a major culprit. Says West German Zoologist Gunter Heidemann: "The dead seals we've found have shown high concentrations of heavy metals and chlorinated hydrocarbons."
Scientists believe the adult seals' immune systems have been weakened by chemical pollutants in the water, making them susceptible to pneumonia induced by a herpes-type virus. Such ravaging of a seal population is not unprecedented: a flu virus, for example, killed more than 500 harbor seals along the coast of New England from Cape Cod, Mass., to Maine over a period of ten months beginning in December 1979. This time, researchers believe, the deadly virus may have originated in slaughterhouse refuse deposited in open dumps along Sweden's western coast. It may then have been transmitted by sea gulls to the seal breeding grounds offshore.
Every year six tons of chlorinated hydrocarbons, 11,500 tons of heavy metals and 1.5 million tons of nitrogen from fertilizers are deposited in the North Sea by rivers and acid rain. An additional 250,000 tons of liquid chemical waste are dumped annually from West German ships into the sea. In Bonn Environment Minister Klaus Topfer last week refused to link man-made pollutants directly to the seal deaths, but he did admit to a "very serious suspicion" that industrial wastes may have played key roles. Topfer has promised to end offshore dumping by the end of 1989. Environmentalists are calling for an immediate ban.
As if the seal deaths were not bad enough, a sudden bloom of yellow algae is spreading a carpet of death in the region. Believed to be stimulated by fertilizers that wash into the North Sea, the algae are suffocating salmon and trout in fish farms, as well as other marine life along 1,000 miles of coastal Denmark, Sweden and Norway.