Dinaric karst water systems support 25% of the total of 546
fish species in Europe, many
endemic. The Neretva River, together with four other areas in the
Mediterranean, has the largest number of
threatened freshwater fish species. The degree of
endemism in the karst ecoregion is greater than 10%. Multiple fish species have small habitats and are
vulnerable, so they are included on the
Red List of endangered fish . The Adriatic basin has 88 species of fish, of which 44 are Mediterranean endemic species, and 41 are Adriatic endemic species. More than half of the Adriatic river basin species of fish inhabit the Neretva, the Ombla, the Trebišnjica, the
Morača Rivers and their tributaries, and more than 30 are endemic.
Invasive species A
pike perch (
Sander lucioperca Linnaeus 1758) (also see
Sander) population in the Neretva River watershed was observed in 1990 for the first time. The Rama River, a right tributary of the Neretva, and its
Rama Lake received an unknown quantity of this
allochthonous species. Population estimates have increased in the Neretva accumulation lakes. This fact confirms previous scientific assumptions of Škrijelj (1991, 1995), who predicted the possibility of pike perch
displacement (migration) from Ramsko Lake to the Rama River and then further downstream to the river and its lakes. In 1990 the perch population made up 1.95% of the fish population in Rama Lake. Within a decade this rose to 25.42% in the nearby
Jablaničko Lake. The fast pace of pike perch population growth and displacements is expected to match the environmental conditions from the mid-ecological valence of this fish. In this sense, it is the established continuous and accelerated growth of the population dynamics of pike perch in Jablaničko Lake, a relatively good representation in
Salakovačko Lake and the beginning of growth of population in
Grabovičko Lake. Parallel with the increase in pike perch is a decrease in endemic
indigenous species like
European chub also white chub (
Squalius cephalus), and the disappearance of rare and endemic species like
Adriatic Dace also Balkan dace (
Squalius svallize also
Leuciscus svallize Heckel & Kner 1858),
Neretvan softmouth trout (
Salmothymus obtusirostris oxyrhinchus Steind.) and
marble trout (
Salmo marmoratus Cuv.). Pike perch causes clearly visible, negative effects on the autochthonous species in
Jablaničko Lake. In Salakovačko Lake these effects are in progress, although less visible, while in Grabovičko Lake it is not yet clearly visible.
Salmonids Salmonid fish from the Neretva basin show considerable variation in
morphology,
ecology and behaviour. Among most
endangered are three endemic species of
trout:
Neretvan softmouth trout (
Salmothymus obtusirostris oxyrhinchus Steind.),
Toothtrout (Salmo dentex) and
marble trout (Salmo marmoratus Cuv.). All three endemic trout species of the Neretva are endangered, mostly due to the
habitat destruction or construction of large/major dams ("large" is higher than 15–20 m; "major" is over 150–250 m).
Cyprinids The most
endangered cyprinids (family Cyprinidae) are endemic. Especially interesting are five
Phoxinellus (sub)species that inhabit isolated
karstic plains (fields) of eastern as well as western
Herzegovina in Bosnia and Herzegovina, which eventually reach the Neretva watershed and/or coastal drainages of south-eastern
Dalmatia. • Karst minnow (
Phoxinellus metohiensis) is considered
Vulnerable (VU). • South Dalmatian minnow (
Phoxinellus pstrossii) is
threatened, but was marked
Data Deficient (DD) and was not designated on
IUCN Red List of Threatened Species Version 2009.1. • Dalmatian minnow (
Phoxinellus ghetaldii) is considered vulnerable. • Adriatic minnow (
Phoxinellus alepidotus) is endemic to Bosnia and Herzegovina and Croatia and occurs in lowland water bodies with little current. It is
threatened due to
pollution and
habitat destruction. It is considered endangered. • Spotted minnow (
Phoxinellus adspersus), is endemic in the Tihaljina River, which is fed by underground waters from
Imotsko field and is connected to the
Trebižat river via the Mlada River. It also occurs in Mostarsko Blato wetlands. Fish were found in the source of the Norin River, a right-hand tributary of the lower Neretva at
Metković, in Croatia, at Kuti Lake, a left-hand tributary of the lower Neretva, at Imotsko field in
Red Lake (Croatia) and the
Vrljika river drainage and near
Vrgorac in the Matica River system. It is considered vulnerable. •
Minnow-nase (
Chondrostoma phoxinus) is considered
Endangered (EN) • Neretvan nase (also Dalmatian nase and Dalmatian soiffe) (
Chondrostoma knerii) is endemic to the Neretva. Neretvan nase is mainly distributed in the lower parts and delta, the Krupa River, Nature Park Hutovo Blato wetlands and Neretva Delta wetlands. It occurs in water bodies with little current. It is threatened by habitat destruction and pollution. It is considered
Endangered (EN). • Adriatic dace also Balkan dace (
Squalius svallize also
Leuciscus svallize Heckel & Kner 1858) is a vulnerable endemic, although also found in
Montenegro and
Albania. Adults inhabit water bodies on the low plains, with little current and in lakes. They feed on invertebrates. It is threatened due to pollution, habitat destruction and due to introduction of other species. • Illyrian dace (
Squalius illyricus also
Leuciscus illyricus Heckel & Kner 1858) inhabits karstic waters of Bosnia and Herzegovina, Croatia and Albania. It occurs in water courses on low plains, with little current. It feeds on invertebrates. It is stressed by habitat destruction, pollution and introduced species. It is considered
Near Threatened (NT). • Turskyi dace (
Leuciscus turskyi also
Squalius turskyi turskyi and
Telestes turskyi) inhabits karstic waters, lake
Buško Blato and the
Krka and
Čikola rivers. It occurs on the low plains, with little current and in lakes. It feeds on invertebrates. Threats include water abstraction and pollution. It is considered
Critically Endangered (CR). •
Dalmatian barbelgudgeon (
Aulopyge hugeli) inhabits karstic streams of
Glamocko field,
Livanjsko field and
Duvanjsko field, lakes Buško Blato,
Blidinje and
Cetina,
Krka and
Zrmanja river drainages. It occurs in
lentic waters and feeds on plants. The fish is threatened by water pollution and habitat destruction and is considered endangered. It is migratory in
Livanjsko field.
Cobitidae The
Neretvan spined loach (
Cobitis narentana Karaman, 1928) is an Adriatic watershed endemic that inhabits a narrow area of the Neretva watershed in Croatia and Bosnia and Herzegovina. In Bosnia and Herzegovina it inhabits only the lower Neretva and its smaller tributaries like the
Matica River. In Croatia it is a strictly
protected species and inhabits only the Neretva delta and its smaller tributaries, the (
Norin) and lake systems of the Neretva delta (
Baćina lakes, Kuti,
Desne,
Modro oko). It is considered
Vulnerable (VU).
Neretva delta endemics The Neretva delta hosts more than 20 endemic species, of which 18 are endemic to the Adriatic watershed, along with three endemic species in Croatia. Nearly half (45%) of the total number of species that inhabit this area are included in one of the categories of threat and are mainly endemic. == Hydroelectric controversy ==