The Bohinj Fishing Association manages three fishing territories:
- Lake Bohinj
- Sava Bohinjka River
- the lower part of the Mostnica River
The association of fish in Bohinj is determined by Lake Bohinj and the Sava Bohinjka River. Those two quite different water areas provide suitable living conditions for various types of fish. Specific types live only in running water, others in still water and some even live in both types of environment.
Until the entry of the Arctic char in Lake Bohinj, lake trout was the dominant fish in the lake. Trout in the lake reached 20 kg in mass and up to 120 cm in length. There are still many lake trout in the lake, but their number has reduced significantly due to intensive catch in the past. They are also endangered due to the entry of lake trout from other territories, even Ohrid Lake in Macedonia.
Lake trout is by its body shape quite similar to the brown trout. But it differs from the brown trout by many black dots of various shapes on its trunk.
It has a lighter underside, in adult fish the tail fin is almost flat, younger fish have an interrupted sideline. Breeding males have the lower jaw slightly curved upwards.
Lake trout likes deep water near the outflows of torrent influxes and ground springs (Ukanc near the outflow of Savica, along the shore below Pršivec mountain, Fužinarski zaliv bay), but we can also watch them prey near the shore. Lake trout is a timid fish and we have to approach it quite cautiously.
Younger fish eat mostly ground food, while adult fish are predators and mostly eat other fish.
Lake trout spawns in autumn – in October and November, they reach their peak in the second half of October, November and in the first half of December. When water level of tributaries is appropriate, they come spawn in the Savica, Mostnica and Ribnica Rivers. When they finish, they return to the deep water areas of the lake. They rarely spawn in the lake (on gravel areas of torrent tributaries to the lake and Govic Waterfall), but only when the water levels of tributaries is low.
Brown trout lives in Lake Bohinj, Sava Bohinjka River and its tributaries. The trout that spawn in the Savica River, look different than the trout from the Sava River. They are larger and have large red spots with metal blue coloured lines. The body of the brown trout has golden yellow lateral line that looks like its dusted with gold. Its meat is of beautiful red colour mostly due to its eating habits. It can grow up to 60 cm. The brown trout living in the Sava River, does not grow to such sizes, is not beautifully golden along the lateral side and does not have such large spots nor such beautiful red coloured meat as the brown trout living in the lake. This shows that besides the lake trout, many types of brown trout lived in Bohinj, which did not cross due to different places or times of spawning. There are many similar examples of co-habitation of various types of brown trout in Europe. The results of genetic research will probably show interesting facts.
Like other waters in Slovenia, other brown trout from the Danube and even Atlantic river basis were entered in the waters of Bohinj. Therefore, it is quite difficult to find Bohinj brown trout in the Sava River and most of its tributaries. These have remained only in the upper streams of some tributaries, such as Mostnica, Suha, Jereka and Ribnica. It is typical for this type of trout to live in very harsh conditions, because the waters have torrent character with less food, thus, they appropriately adjusted their living habits. The body of this type of brown trout is rounder than the body of the brown trout living in the Sava River. Tail and adipose fins are red, the meat is light red and sometimes yellowish. Red spots are smaller and densely located all over the body, and even mixed with black spots. These preserved remnants of the initial brown trout and lake trout, which come to spawn in the Savica, are the basis to repopulate brown trout in Bohinj.
Brown trout mostly eats invertebrates and insects on the surface of water, large trout even eat other fish.
Brown trout spawns at the end of autumn and in the beginning of winter, spawning peak is in November. The most important spawning areas are in the tributaries of the Sava River, i.e. Mostnica, Ribnica, Belca, Bezdena and Savica, the brown trout also spawns in the Sava River. Due to intensified elimination of gravel from the riverbed of the Sava River, the brood fish have more difficult access to spawning areas when the water level is low.
Grayling’s habitat includes the Sava River, its tributaries and Lake Bohinj. The most beautiful territory where this type of fish lives, is the lower stream of the Mostnica River, a special pride of the fishermen in Bohinj.
Grayling, which populates the Sava Bohinjka River, has a flat body, an arched back and a typically high and long rainbow-coloured dorsal fin that looks like a chess board. Its body is covered with relatively large scales. Its head is relatively small and without scales, it has soft lipped-mouth. The Sava grayling prefers swimming near torrents and channels. It is quite quickly noticeable there by fishermen, because the fish is recognisable by the beautifully coloured orange-red fins.
In the past decade, the grayling population has been greatly reduced by cormorants, poor water quality and enhanced excavation of gravel also have a bad effect on grayling.
Grayling feeds with invertebrates, but also insects on water surface. It is quite popular among fly-fishermen.
In Bohinj, grayling spawns in April and at the beginning of May. It spawns in the Sava, Mostnica and Ribnica Rivers, near Brod, Kamnje, Polje, Laški Rovt and in the lower stream of the Mostnica and Ribnica Rivers.
Artificial breeding of grayling in Slovenia also began in Bohinj. Breeding was based on breeding fish from the Sava River and on river plankton which was the source of first food for the grayling fry. Unfortunately, breeding has been abandoned in the past few years and the fish farm below Pršivec mountain is dilapidating. The fishermen in Bohinj should restart breeding grayling and keep the tradition.
Other autochthonous fish species
We can find a bunch of other autochthonous fish species in Bohinj.
Burbot lives in the lake. Fishing for burbot in the lake has been diminishing for the past few years. This can also be connected to the change in Arctic char fishing.
Chub populates the lake and the Sava River. We can see shoals of chub in the lake and they seem as if they are sun-bathing under the surface. The number of chub in the Sava River has been strongly reduced by the presence of the Danube salmon.
Danube salmon is only an occasional guest in the Sava River. Due to intensive input of this type of fish, the number of bleak in the Sava River has also been affected.
The souffia is stable in the lake and in the Sava River. The same is true for the population of the common dace.
Bullhead in the Sava River is becoming quite rare. This is a result of water quality and gravel elimination. Its population quantity is good in the lake.
Minnow was used to catch the Arctic char. Currently, its population is decreasing due to the presence of bass, which has emerged in the lake.
We can also find the southern barbel in the Sava River tributaries. Stone crayfish can also be found here.
Non-native fish species
The waters in Bohinj were also subject to entering non-native – allochthonous fish species.
The first such species was entered in 1943, i.e. the Arctic char. It has adapted to lake conditions and started spawning successfully, therefore, it is currently the most common fish in Lake Bohinj. It can grow to 70 cm and weigh up to 4.6 kg.
Arctic char can most frequently be found in Fužinarski zaliv bay, in the depths below Pršivec mountain and in Ukanc, at the outflow of the Savica River.
It feeds on lake plankton, ground organisms and small fish.
The Arctic char spawns in the lake in October and November, the largest breeding area is below the Govic Waterfall.
Regardless of the fact that the Arctic char is a non-native fish, it is very important for sport fishing. Due to its culinary importance, perhaps it should be integrated in the local cuisine to a greater extent.
Rainbow trout is entered in the Sava River. Only sterile fish have been entered in the past few years. Regardless of this fact, the rainbow trout has been successfully naturally reproducing in Bohinj.
The last non-native fish is the bass. It was used in the past as bait to catch lake trout and has, like in many places worldwide, become a species living in the lake. Its number is rapidly increasing. Since it is a successful predator, it has had quite an impact on the population of the minnow, and other fish populating the lake, are also endangered.