Baltic dolphins

It emerges above the surface of the water only for a moment necessary to draw air. Only when it is feeding do we have the opportunity to see it flying above the water.

Harbour porpoises are one of the most enigmatic animals in the Baltic Sea. Meeting them is not easy. We need to be patient and, on a clear day, persistently observe the calm surface of the water, looking for a triangular, dark grey dorsal fin. Harbour porpoise (Phocoena phocoena) is a species of marine mammal belonging to the order of cetaceans and sub-order of toothed whales. Their coloration is dark grey on the back and gradually turns lighter in the ventral part. Unlike dolphins, their beak is round, not protruding, and the dorsal fin is low and triangular (in dolphins it is tall and sickle-shaped). They are the smallest whales in the world. Adult specimens reach a maximum length of 180 cm and a weight of about 60-70 kg, thus being almost half the size of dolphins. Young, immediately after birth, are about 80 cm long. Throughout her life, a female gives birth to a maximum of 4 calves, so it is characteristic of this species to take care of its offspring. Immediately after birth, the mother helps the calf get to the surface of the water so that it can take its first breath. The female always gives birth to only one calf, which she feeds for 6 to 8 months. When

it grows up, it often swims for some time with its mother until its completely independent. In the wild, porpoises live up to 17 years. Unlike their dolphin cousins, porpoises are shy and introverted animals. They avoid contact with the man and flee to the sound of a motor boat engine. They usually swim alone, only sometimes you can spot a small group starting a hunt or a female with her young. Each time the porpoise emerges, you can hear a characteristic "puff", corresponding to a sudden ejection of used air through the nostril at the top of the head. They are most often found in seas in the coastal zone, they like shallow waters, sometimes they inhabit rivers and canals. In Europe, they inhabit the waters of the North Sea, Black Sea and the Baltic Sea. The harbour porpoise is hard to find in our sea also because its numbers have dropped dramatically in recent years. Not so

long ago, tens of thousands of this species swam in the waters of the Baltic Sea. Unfortunately, there were so many of them that they often got trapped in fishing nets, destroying them and often the entire catch of the fisherman. They began to be treated as pests and exterminated. Additionally, since the 14th century, porpoises, like seals, have been regularly caught for their meat and fat. In the early twentieth century, you could even get a special financial bonus for killing a porpoise. Currently, the population of the Baltic porpoises is estimated at about 500, which is why the International Union for Conservation of Nature (IUCN) in 2008 gave it the status of critically endangered with extinction. Today, one of the main threats to porpoises is fishing nets. They are made of much more durable materials than before and, at the same time, less visible in water, which means that they are often a deadly trap for these animals. Harbour porpoises, similarly to dolphins, use echolocation, so increasing underwater noise poses another threat to them. Military or geological detonations, various types of underwater works or even the sounds of motor boat engines causes that these animals feel stunned and startled, which makes them lose their orientation underwater. They often have problems with communication, locating food, and are not able to correctly recognise underwater obstacles. We can all help these small mammals, first of all being aware of the dangers that await them. It is also important that we know what to do when we find an injured animal in need on the shore. First of all, we should notify the relevant services, such as the municipal police, the WWF Blue Patrol or the Marine Station of the Institute of Oceanography of the University of Gdańsk named after Professor Krzysztof Skora. We can also try to limit and best avoid water sports that are so dangerous for them. Let's hope that thanks to such little and big gestures, we will be able to save these wonderful animals and we will have the opportunity to admire them during our dives.

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