Fish and fishing
Since antiquity the lake has been well stocked with fish, and fishing has always been an important resource for the local economy as well as the basis for the local diet.
Fish which have always been present in the lake are eel, pike, smelt, rudd, tench and chub. Among the crustaceans are prawn and river crab. Other species such as stickleback, shad, loach, roach and Alburnus alborella, which are rarely seen today, are probably native.
All of these species, even those which are irrelevant from a commercial point of view, are still important because they contribute to the richness and the balance of the entire ecosystem. In fact, the more varied an environment, rich in many well-distributed species, the better it can support the inevitable impact of human activity.
Which fish have been recently introduced into the lake?
The lake doesn’t have any tributaries and only one small outflow, the Marta river. The populating of new species of fish, rather than by natural means, has happened principally by the work of man, whether with voluntary targeted introductions, or through campaigns of re-population carried out in a non-controlled way, in particular those carried out for sport fishing. The species introduced by man for professional fishermen are lake whitefish – introduced for the first time at the end of the 1800s – and European perch.
Other species, introduced primarily for sport fishing but also for the fight against mosquitoes – or simply through carelessness – are black bass, pumpkinseed, catfish, carp, crucian carp and gambusia.
Are there any risks to lake fishing?
The non-native species listed above are by now naturalised and in relative balance with the native. Particular risks are posed by the presence of the Louisiana red prawn (the so-called ‘killer prawn’, aggressive and voracious) and turtles of the genus trachemys. For the fish the principal risks can be connected to the introduction of carnivorous species or scavenger fish like the Wels catfish.
The eutrophication of the water, coming from the anthropisation of the lake banks and from a too lax control policy that allows the immission of nutrients into the lake, results in the reduction of the biodiversity of the fish fauna, particularity the most sensitive species. The oligotrophic lake is characterised by the prevailing presence of Salmonidae like whitefish, while the stage of mesotrophia allows the dominance of Percidae like perch and others. The Cyprinidae group like carp and tench dominates eutrophied lakes. Eutrophication presents a particular risk to whitefish because it lays its eggs in fresh, well-oxygenated low water. As has been seen in other lakes, its reproduction can be interrupted by the depletion of oxygen at the lake bottom.
Climate change can affect the reproductive cycle of animals; an increase in temperature can disturb the reproductive processes in cold freshwater species.
Other problems?
One major problem is our insufficient knowledge of the fish fauna of the lake.
How many fish are there?
Of which species?
What are the characteristics of their reproductive cycles?
How much is caught?
What is the evolution of these figures over time?
This makes vain every attempt at planning, even of re-population (valid only for extraordinary intervention, in case of environmental emergency).
What are the prospects for fishing on the lake?
The prospects are tied to the development of the product. The species most fished are today whitefish, pike, tench and eel. A winning strategy, one which will also protect the environment, could be to spread knowledge of the product. Having a regulation that integrates all the activities and techniques of artisan and sustainable fishing would protect the catch with a mark of authenticity, “fish of the lake”.
