the ingredients. The main dish of the Christmas dinner is usually a northern pike, in contrast to the ham which is eaten in mainland Finland. Every Christmas the fishermen of Korpo deliver a pike for the president's table. Nature and conservation The islands provide a unique and diverse environment for wildlife. The bigger islands resemble the coastal regions of continental Finland whereas skerries have a radically different environment. Smaller islands are devoid of trees, but still harbour a rich plantlife. The environment is sunny, has a relatively long growing season and is fertilised by guano. On the other hand, nearly constant wind and thin or non-existent soil limit plant growth. The very low salinity of the Baltic Sea makes splashes of seawater more benign for plant life. While most of the islands are rocky, some are actually extensions of the Salpausselkä ridge system, and thus composed of terminal moraine. Such islands include Örö and Jurmo. The flora and fauna in these islands is more diverse than in their rocky neighbours. The conditions can vary radically even within one small island, due to the features of the rock on which the islands are based. There may be small patches of fresh-water bogs, ponds of fresh water, ponds of brackish water, bushes, meadows, barren rocks, wind-beaten shores and sheltered coves on an island only a few tens of meters in diameter. Many plants have altered phenotypes due to the environment. For example, junipers on small islands grow only to a height less than , but can cover several square meters. In contrast to the terrestrial and coastal ecosystems of the islands, the sea itself has a relatively low biodiversity. The reason for this is the brackish nature of the water. The salinity is only 0.6% in the Archipelago. The salinity has also varied greatly during the past, making it difficult for species to adapt. However, the great number of individuals indicates a favourable environment. Typical fish species are the Baltic herring, pike, white-fish, perch and flounder. The area is home to many species which are not found elsewhere in Finland. Harbour porpoise is one example of such species. It is the only cetacean which is regularly sighted in the northern part of the Baltic Sea. The current population in the entire Baltic is estimated at 600 individuals, down from estimated 10 to 20 thousand a century ago. Another example is white-tailed eagle,