18. Endangered species
Contents
18.1 What is an endangered species?
An endangered species is a species that is in danger of becoming extinct. Therefore, conservation measures must be taken to protect the species. Most species become endangered as a result of human activity.
Threats can be considered at several levels. When looking at the problems threatening the survival of a species globally, the probability of the species disappearing altogether is considered. Extinction, by definition, is when all individuals of a given species die. Such an event is irreversible.
International Union for Conservation of Nature’s Red List of Threatened Species, or Red List in short, has seven levels of conservation: least concern, near threatened, vulnerable, endangered, critically endangered, extinct in the wild, and extinct.
The long-tailed duck is one of our endangered bird species.
18.2 The elusive eel
The eel (Anguilla anguila) is one of the most mysterious species living in Finnish water ecosystems. It is also an endangered species.
The living habits of eels are mostly unknown. Eels live in freshwater environments such as lakes and rivers. They are predators that use other fish and crabs as their food.
The eel is a migratory fish. When it has grown into an adult, it embarks on a spawning migration. It travels through rivers in order to end up in the sea. Once in the sea, it begins its long migration. Based on modern research, eels have been discovered to migrate to the Sargasso Sea on other side of the Atlantic. This is where the species is thought to reproduce.
The young eel larvae develop in the Sargasso Sea and move towards Europe with the help of the Gulf stream. Finally, the larvae develop into so-called glass eels, which travel inland through rivers. These glass eels grow and gradually develop into adult eels.
Eels are a long-lived species. They can live in lakes and rivers for decades before embarking on their spawning migration.
Hydroelectric power plants provide the greatest threat to eels as a species. Dams block the waterways that eels need to use to reach the sea during their migration. In addition to this, there are no restrictions on eel fishing in Finland. As a result of this, eel populations are rapidly decreasing.
Protecting eels is difficult, because it requires changes in the hydroelectric power plants that block their migration routes. Power plants should build "fish roads", through which migratory fish can bypass the power plant safely. Restricting eel fishing is another challenge. Although eels are extremely endangered, they are considered a popular food in many European countries. As a result, eels are fished in great quantities despite their endangered status.
An eel has been caught in Italy.
18.3 The endangered Saimaa ringed seal
The Saimaa ringed seal is a protected, extremely endangered seal species. It is a subspecies of the Baltic ringed seal. For many people, the Saimaa ringed sealis a well known symbol of Finnish environmentalism.The Saimaa ringed seal inhabits Lake Saimaa and some of the smaller lakes that surround it. The species became isolated from the Baltic ringed seal after the last ice age, when Saimaa became a lake as a result of post-glacial rebound.
Only about 380 ringed seals remain in Saimaa. Because seals reproduce and grow slowly, the population will continue to decrease as a result of the problems caused by human activity. The number of reproducing seals is low, whereas the mortality rate of their pups is relatively high. The most common cause of death for ringed seal pups is getting caught in fishing nets. In addition, increasingly warm winters mean that the seals cannot dig snow caves where the young pups are protected from the cold.