Marble trout is a species of freshwater fish

Freshwater fish

Freshwater fish are fish that spend some or all of their lives in freshwater, such as rivers and lakes, with a salinity of less than 0.05%. These environments differ from marine conditions in many ways, the most obvious being the difference in levels of salinity...

 in the Salmonidae

Salmonidae

Salmonidae is a family of ray-finned fish, the only living family currently placed in the order Salmoniformes. It includes salmon, trout, chars, freshwater whitefishes and graylings...

 family, the second largest European trout species, second in size only to huchen

Huchen

The huchen or Danube salmon is a species of freshwater fish in the salmon family of order Salmoniformes. It is the type species of its genus...

 (Hucho hucho). The marble trout is found in rivers of the Adriatic basin in the Neretva

Neretva

Neretva is the largest river of the eastern part of the Adriatic basin. It has been harnessed and controlled to a large extent by four HE power-plants with large dams and their storage lakes, but it is still recognized for its natural beauty, diversity of its landscape and visual...

 river in Bosnia and Herzegovina

Bosnia and Herzegovina

Bosnia and Herzegovina , sometimes called Bosnia-Herzegovina or simply Bosnia, is a country in Southern Europe, on the Balkan Peninsula. Bordered by Croatia to the north, west and south, Serbia to the east, and Montenegro to the southeast, Bosnia and Herzegovina is almost landlocked, except for the...

, Po River

Po River

The Po |Ligurian]]: Bodincus or Bodencus) is a river that flows either or – considering the length of the Maira, a right bank tributary – eastward across northern Italy, from a spring seeping from a stony hillside at Pian del Re, a flat place at the head of the Val Po under the northwest face...

 in Italy

Italy

Italy , officially the Italian Republic languages]] under the European Charter for Regional or Minority Languages. In each of these, Italy's official name is as follows:;;;;;;;;), is a unitary parliamentary republic in South-Central Europe. To the north it borders France, Switzerland, Austria and...

, Zeta

Zeta

-Science:* Zeta functions, in mathematics** Riemann zeta function* Zeta potential, the electrokinetic potential of a colloidal system* Tropical Storm Zeta , formed in December 2005 and lasting through January 2006* Z-pinch, in fusion power...

 river in Montenegro

Montenegro

Montenegro Montenegrin: Crna Gora Црна Гора , meaning "Black Mountain") is a country located in Southeastern Europe. It has a coast on the Adriatic Sea to the south-west and is bordered by Croatia to the west, Bosnia and Herzegovina to the northwest, Serbia to the northeast and Albania to the...

, Soča

Soca

The Soča or Isonzo is a 140 km long river that flows through western Slovenia and northeastern Italy. An Alpine river in character, its source lies in the Trenta Valley in the Julian Alps in Slovenia, at an elevation of around 1,100 metres...

 and Idrijca

Idrijca

The Idrijca is a river flowing through the Idrija Hills and Cerkno Hills. It is 60 km long. It rises near Vojsko, flows towards northeast and after passing through Idrija turns to the northwest. After passing through Spodnja Idrija and Cerkno it joins the Soča in Most na Soči.The river basin...

 rivers in Slovenia

Slovenia

Slovenia , officially the Republic of Slovenia , is a country in Central and Southeastern Europe touching the Alps and bordering the Mediterranean. Slovenia borders Italy to the west, Croatia to the south and east, Hungary to the northeast, and Austria to the north, and also has a small portion of...

 and possibly in Albania

Albania

Albania , officially known as the Republic of Albania , is a country in Southeastern Europe, in the Balkans region. It is bordered by Montenegro to the northwest, Kosovo to the northeast, the Republic of Macedonia to the east and Greece to the south and southeast. It has a coast on the Adriatic Sea...

.

Marmorated trouts

Adding to the confusion of salmonid taxonomy, there are other trout with marble pattern beside Salmo marmoratus. One is trout from the river Otra, Norway. A certain percentage of brown trout from that river has marble pattern. In all other aspects, these trout are identical to the non marble brown trout from the same river. This is an example of intrapopulational polymorphism (biology)

Polymorphism (biology)

Polymorphism in biology occurs when two or more clearly different phenotypes exist in the same population of a species — in other words, the occurrence of more than one form or morph...

.

Recent studies also imply that marble trout from Neretva and Montenegro are not closely related to Salmo marmoratus. The pattern probably developed in geographically remote regions independently. In addition, genetic studies revealed that marble trout from Neretva is genetically indistinct from Salmo dentex

Salmo dentex

Salmo dentex is a variety of trout, a freshwater fish in the Salmonidae family, found in the western Balkans. The identity, biological dinstinctness and species status of the dentex trout are however not properly clarified...

.

Appearance, Biology and Ecology

The marble trout has a long, cylindrical body, slightly compressed laterally, with a large head (22-25% of the body length) which is why it is also known as "Glavatica" ("glava" - head) in Bosnia and Herzegovina

Bosnia and Herzegovina

Bosnia and Herzegovina , sometimes called Bosnia-Herzegovina or simply Bosnia, is a country in Southern Europe, on the Balkan Peninsula. Bordered by Croatia to the north, west and south, Serbia to the east, and Montenegro to the southeast, Bosnia and Herzegovina is almost landlocked, except for the...

. The most obvious characteristic of marble trout is of course the marble pattern. The intensity of colour varies considerably upon the surroundings. Some marble trout have red spots that merge with the rest of the pigment, always only along the lateral line.

Its average size is 30-70 cm. The largest specimen in Slovenia

Slovenia

Slovenia , officially the Republic of Slovenia , is a country in Central and Southeastern Europe touching the Alps and bordering the Mediterranean. Slovenia borders Italy to the west, Croatia to the south and east, Hungary to the northeast, and Austria to the north, and also has a small portion of...

 was a 117 cm and 24 kg female (found dead) , largest living specimen caught was 120 cm and 22.5 kg . There are reports of individuals weighing up to 30 kg. The largest specimens were found in Bosnia and Herzegovina

Bosnia and Herzegovina

Bosnia and Herzegovina , sometimes called Bosnia-Herzegovina or simply Bosnia, is a country in Southern Europe, on the Balkan Peninsula. Bordered by Croatia to the north, west and south, Serbia to the east, and Montenegro to the southeast, Bosnia and Herzegovina is almost landlocked, except for the...

, inhabiting the Neretva

Neretva

Neretva is the largest river of the eastern part of the Adriatic basin. It has been harnessed and controlled to a large extent by four HE power-plants with large dams and their storage lakes, but it is still recognized for its natural beauty, diversity of its landscape and visual...

 river from below town of Konjic

Konjic

Konjic is a town and municipality in Bosnia and Herzegovina. It is located in northern Herzegovina, around southwest of Sarajevo. It is a mountainous, heavily wooded area, and is above sea level. The municipality extends on both sides of the Neretva River. The town of Konjic, housed about a third...

 downstream to town of Čapljina

Capljina

Čapljina is a town and municipality of the same name in Bosnia and Herzegovina. It is located in the Herzegovina-Neretva Canton of the Federation of Bosnia and Herzegovina. Čapljina is located on the border with Croatia a mere from the Adriatic Sea....

, mostly in canyon section from town of Jablanica

Jablanica

Jablanica or Yablanitsa may refer to:* Jablanica, Bosnia and Herzegovina, a town in Herzegovina* Yablanitsa, a town in Lovech Province, Bulgaria* Yablanitsa, Sofia Province, village in Sofia Province, Bulgaria* Jablanica, Zlatibor, village in Serbia...

 to city of Mostar

Mostar

Mostar is a city and municipality in Bosnia and Herzegovina, the largest and one of the most important cities in the Herzegovina region and the center of the Herzegovina-Neretva Canton of the Federation. Mostar is situated on the Neretva river and is the fifth-largest city in the country...

, and later after construction of Jablanica dam on the Neretva

Neretva

Neretva is the largest river of the eastern part of the Adriatic basin. It has been harnessed and controlled to a large extent by four HE power-plants with large dams and their storage lakes, but it is still recognized for its natural beauty, diversity of its landscape and visual...

 river in Jablaničko Lake. Trout

Trout

Trout is the name for a number of species of freshwater and saltwater fish belonging to the Salmoninae subfamily of the family Salmonidae. Salmon belong to the same family as trout. Most salmon species spend almost all their lives in salt water...

 become sexually mature at the age 3+ (males) and 4+ (females), they spawn during November and December.

Marble trout is piscivorous, feed mainly on smaller fish and benthic invertebrates.

Its natural habitat

Habitat

* Habitat , a place where a species lives and grows*Human habitat, a place where humans live, work or play** Space habitat, a space station intended as a permanent settlement...

 is river

River

A river is a natural watercourse, usually freshwater, flowing towards an ocean, a lake, a sea, or another river. In a few cases, a river simply flows into the ground or dries up completely before reaching another body of water. Small rivers may also be called by several other names, including...

s with a summer temperature of 15°C.
Hybridization with foreign trout stocked for angling. Water extraction and pollution. In Bosnia and Herzegovina main threats are habitat loss (habitat destruction) due to constructed of five large dams on the Neretva river and plans for construction of several new dams on the upper course of the Neretva, water pollution, overfishing (sportfishing, food, including poaching) and hybridisation  with introduced species

Introduced species

An introduced species — or neozoon, alien, exotic, non-indigenous, or non-native species, or simply an introduction, is a species living outside its indigenous or native distributional range, and has arrived in an ecosystem or plant community by human activity, either deliberate or accidental...

 of trout.

All eight remaining genetically pure marble trout populations were found in remote streams of the River Soča

Soca

The Soča or Isonzo is a 140 km long river that flows through western Slovenia and northeastern Italy. An Alpine river in character, its source lies in the Trenta Valley in the Julian Alps in Slovenia, at an elevation of around 1,100 metres...

 basin. From these populations the Tolmin

Tolmin

Tolmin is a small town and municipality in the Littoral region of Slovenia.-Geography:Tolmin, the old town that gave the name to the entire area , is the largest settlement in the Upper Soča Valley , as well as its economic, cultural and administrative centre. It is located on a terrace above the...

Angler's Society launched a reintroduction programme.