Italian nase  (Chondrostoma soetta)

The Italian nase is classified as Endangered (EN) on the IUCN Red List (1).

Once common in Italy, Switzerland and Slovenia, the Italian nase (Chondrostoma soetta) is now considered to be threatened with extinction (1). This medium-sized fish has a sideways-compressed body, a small, conical head and a forked tail with two pointed lobes. It has a prominent mouth with rigid lips, used principally for eating algae. The Italian nase is typically grey, with silver sides dotted with black and a white abdomen. The dorsal fin is silver-green, while the other fins range in colour from light pink to orange or yellow (3).

Today, the Italian nase can only be found in northern Italy and in the southern part of Switzerland. It is now extinct in Slovenia and in the Isonzo River basin in Italy, due to the introduction of the common nase (Chondrostoma nasus) (1).

The preferred habitats of the Italian nase are deepwater lakes (1) and the lower and middle reaches of large rivers, with a moderate current (2). It prefers clear waters, with gravel bottoms and a large amount of vegetation. During the summer, the Italian nase can be found hiding behind big rocks or aquatic plants situated in well-oxygenated rapids, while in winter it usually migrates to deeper and warmer waters (3).

The Italian nase is an omnivorous fish, with a diet comprising algae, organic debris and some invertebrates (mainly snails) (2) (3).

A gregarious fish, the Italian nase lives in schools, sometimes with other cyprinids (fish in the Cyprinidae family). The spawning season begins at the end of April, when the Italian nase usually migrates to small streams or creeks, where each female lays up to 100,000 green eggs. The eggs hatch after fifteen days, and the Italian nase reaches sexual maturity at three to four years of age (3) (4).

Pollution and the extraction of river waters, mainly due to agricultural activities, are posing a serious threat to the survival of this fish, as is the introduction of some non-endemic species, including the wels catfish (Silurus glanis), the common nase (Chondrostoma nasus) and the common roach (Rutilus rutilus) (1). These species are generally introduced for sport-fishing, a popular activity with Italian people (3).

Since the Italian nase needs to migrate to suitable places to spawn during spring, dams and other barriers also represent a threat to the survival of this animal. Predation by cormorants (Phalacrocorax carbo) is also of concern, as cormorants are becoming a serious pest and taking large numbers of fish in some locations in Italy (1).

Climate change also poses a long-term threat to the Italian nase (1), as an increase in global temperatures is predicted to result in a decrease in freshwater in the Mediterranean basin region (7).

The Italian nase is protected in Europe under Appendix III of the Convention on the Conservation of European Wildlife and Natural Habitats (also known as the Bern Convention) (5). Restoration projects are being discussed in Italy, which would recreate suitable zones in rivers and lakes in which freshwater fishes could live.  Creating ‘safe passages’ so that the Italian nase can migrate easily between lakes and spawning sites, avoiding any dams or other barriers, would be a solution to the problem of population fragmentation (6).

To learn about efforts to protect freshwater ecosystems see:

• The Nature Conservancy:
  http://www.nature.org/initiatives/freshwater
• Conservation International:
  http://www.conservation.org/learn/freshwater
• Zoological Society of London:
  http://www.zsl.org/conservation/regions/uk-europe/fish-net,1334,AR.html