SOS for the Baltic Harbour Porpoise

2007 was a very bad year for harbour porpoises in the Baltic Sea . On the basis of the number of stranded specimens found along the German coast from Flensburg to Greifswald , the German Society for the Conservation of Marine Mammals (Gesellschaft zum Schutz der Meeressäugetiere, GSM) has come to the conclusion that over 150 of these small whales were killed. A dramatic conclusion.”This year we found more than twice as many cadavers as in 2006”, says Hans-Jürgen Schütte, coordinator of the GSM’s project “Wassersportler sichten Schweinswale” (“Pleasure Boaters on the Look-Out for Harbour Porpoises”).

The causes of death are almost always anthropogenic, i.e. the animals’ deaths are human-induced. The sensitive habitat of the Baltic Sea has been degraded and turned into a much frequented shipping lane. Its waters are polluted by industry and agriculture and over-fertilized. Underwater ordnance, military exercises and the exploitation of natural resources such as gravel, sand, oil and natural gas have turned this unique ecosystem into a hostile environment.

In its 2002 Recovery Plan for the Baltic Harbour Porpoise (“Jastarnia Plan”), ASCOBANS, the international agreement dedicated to the conservation of small cetaceans, identified fisheries as the number-one cause of porpoise deaths. Fishermen do not deliberately catch porpoises, but far too many of these animals die in nets deployed for other species. They are “bycaught”. Whales primarily use echolocation for orientation and to locate prey. Modern nylon nets, however, are invisible to them and cannot be detected by means of echolocation. Porpoises become entangled in the nets and suffocate. “Despite the fact that this small, snub-nosed marine mammal is comprehensively protected by legislation, more animals are killed than born,” says Petra Deimer, marine biologist with the GSM. “This ratio is unsustainable for any population.”

Without strict measures, the porpoise will soon become extinct in the Baltic Sea . Consequently, the Jastarnia Plan unequivocally requires a change of fishing methods from gear known to endanger porpoises to less dangerous gear. Drift nets should be replaced by longlines, set nets by fish traps and fish pots. There is no lack of legislation and regulations, but, as in many other cases, implementation is insufficient. If the Baltic Sea states applied the Jastarnia Plan, they could save the harbour porpoise.

Five years after the elaboration of the plan, nearly all fisheries institutions remain in a state of stoic inactivity. Instead of implementing the recovery plan, attempts are made to cover up the cause of porpoise deaths. The GSM is in possession of a photo of a stranded porpoise with a brick tied to its fluke. Along the coast of Schleswig-Holstein , GSM member Andreas Pfander found more dead animals than ever before. Many of them had their bellies slashed open in order to ensure that the carcasses would not surface or would only do so long after the animals had died. The intention behind this is clear: the later a cadaver surfaces the more difficult it is to detect tell-tale net marks, which would give away the fact that the porpoise died in a net.

Only a few years ago, bycatches were reported and the carcasses made available to the University of Kiel ’s Research and Technology Centre Westcoast (FTZ) in Büsum. Scientists examined them to determine their state of health and that of the marine environment. But nowadays, we are told, there is no such thing as bycatch… For this reason, it is even more important for the coastal states of the Baltic and North Seas to monitor strandings of dead animals. Regardless of whether they are killed by fisheries or die of other causes, the cadavers of marine mammals, i.e. whales and seals, allow us to draw conclusions as to the causes of their deaths and the state of their habitats. Or must we assume that, for instance, in the State of Mecklenburg-Western Pomerania nobody is interested in this? After all, marine mammals, at the top of the food chain, are indicator species providing clues to the state of the environment. In Mecklenburg-Western Pomerania, collection of data and cadavers is gladly left to volunteers.

For further information, please contact GSM www.gsm-ev.de.

Tel.: + 49 4106 4712