The return of the otter

Sicily was once one of the Italian regions where the European otter (Lutra lutra) flourished, until a combination of climatic and human-driven changes drove it to local extinction. No official scientific record confirms the otter’s historical presence in Sicily with certainty, yet numerous references in the literature point to a coherent and reliable picture. Between the 18th and 19th centuries, scholars such as Doderlein and Cavazza reported direct observations of the species in well-documented locations, including the former Lentini marshes. In light of this evidence, it is reasonable to regard the otter as a stable component of Sicilian river ecosystems. (Find more info here)

To understand how to act in the future, we first need to understand the otter’s trajectory in the past. In the 18th and 19th centuries, Mediterranean rivers, and Sicilian ones in particular, were highly dynamic systems, marked by frequent shifts in course and flow and closely connected to the environments around them. They were far less polluted, with none of the pesticides or heavy metals found today, and still largely untouched by artificial structures such as dams and weirs. Their banks were rich in riparian vegetation, which is essential for sustaining biodiversity. These ideal conditions supported a great variety of animal life, including the native fish communities that are so important, trophically, to the species we are concerned with here: the European otter (Lutra lutra).

This favourable situation lasted roughly until the end of the 19th century, after which both river habitats and the otter began to decline. The main factors were:

• Physical modification: dams, weirs, channelisation and land reclamation, which fragmented rivers, destroyed habitat and drained wetlands.
• Land use: water abstraction, unsustainable flow management and intensive agriculture, which increased pollution.
• Biological alteration: the introduction of non-native species, competition with native species and disruption of the food web.
• Direct pressure: hunting, persecution and road mortality.

Together these pressures hit the otter hard. A more fragile ecosystem, with fewer fish and degraded habitats, made survival increasingly difficult and ultimately led to its disappearance.

The relationship between human communities and rivers is a socio-ecological system, in which natural dynamics and human activity continually shape one another. The Simeto is a particularly telling case, showing how human intervention can transform a river ecosystem from the ground up. Once an ideal habitat, it was gradually altered by intensive water use, land reclamation and the construction of barriers, steadily losing its natural character. One recent focus is the Passo Martino weir, which breaks the river’s continuity. It blocks fish migration, alters the distribution of organisms and encourages the spread of non-native species. The result is a simplified food web and a loss of biodiversity, leaving the environment increasingly unsuitable for sensitive species. Changes like these show that people do not merely use rivers; they reshape their ecological balance.

A more integrated approach to river management is now emerging, one that tries to reconcile human needs with biodiversity conservation. For the Simeto, the first step would be to restore river continuity by removing the Passo Martino weir, followed by the rehabilitation of habitats. (Source)

Returning to the otter: around 800–1000 individuals now live in Italy. That is well below the minimum viable population of 4000–5000, but still encouraging, given that by the end of the 1990s only 220–260 remained. Whereas the species was once confined to central and southern Italy, absent from the islands and the north, it has now expanded into the northern regions such as Piedmont and neighbouring areas. This has been made possible by the ecological corridors par excellence: rivers.

It is precisely because rivers matter so much that several projects share the ultimate goal of river rewilding:

• HOLRIVERMED: ecological models to predict the positive and negative effects on both river systems and human activity.
• FLUMEN: the impact of environmental change on river dynamics, with a particular focus on the hydromorphology of Eurasian rivers.

Any reintroduction in Sicily has to start from the otter’s needs:

1. It is a semi-aquatic river mammal, so it requires clean water free of pollutants, an unbroken river course and a varied habitat that offers both deep water for hunting and calm, dry areas for resting and shelter.
2. It is an apex predator, roughly 75% predominately piscivorous, and functions as a quasi-keystone species. Studies of its scat show that the otter plays a fundamental role in regulating the river’s trophic balance: where both native and non-native species are present, it preys preferentially on the non-native ones, helping to restore the natural food web and biodiversity.
3. It is crepuscular, a trait linked to lower human disturbance at night and greater hunting success.
4. It needs shelter along the banks: dense vegetation, natural cavities, exposed tree roots and unmodified banks.

Yes. The reintroduction of the otter to Sicily is now considered feasible, thanks to a combination of favourable ecological and management factors. Despite historical degradation, some river systems still retain characteristics that suit the species, or that could be restored. With its strong dispersal ability and adaptability, the otter could recolonise these environments on its own, especially as part of a functioning ecological network. Given sustainable management, the otter’s return to Sicily becomes a concrete, achievable goal, one that could drive river restoration while opening up opportunities for local development.

A few further questions are worth asking. What were the key drivers behind the otter’s disappearance? Have they really been overcome, or do they persist today? Is the otter absent only from Sicily’s rivers, or also from the memory and cultural identity of local communities? And can that connection be rebuilt by bringing together conservation, local communities and a sense of place?