Lake Garda Alborella in Decline: Ecosystem Imbalance and Conservation Efforts

After the carpione, even the aola is in crisis. The decline of alborella presence in the waters of Italy’s largest lake dates back at least to 1995. And despite a recent partial recovery, the aola continues to remain a species under close watch. In fact, besides the initiatives by the provinces bordering Garda, the Ministry of Environment has also taken an interest in this small, silvery fish.

Ministry Interventions and Data on the Alborella Status

Hon. Edo Ronchi, just days before leaving his position as minister, responded to a parliamentary question posed by lake senator Massimo Wilde, who urged him to address the issue of whether continuing to introduce hundreds of millions of coregonids into Garda is still appropriate. Wilde asked if the rapid increase in vimba has been causing an imbalance in the Benaco ecosystem, with the consequence that another valuable fish, namely the carpione, would also suffer.

According to data and reports from ichthyologists, the alborella is experiencing a decline almost everywhere in Italy. In the large pre-Alpine lakes, the phenomenon, which began in the early 1990s, has been very pronounced; however, localized reports suggest there has been some recovery of the species.

Veronese ichthyologist Ivano Confortini, advisor to the Verona Provincial Administration, states that in Garda, the alborella has suffered a decline of between 95-98%. Prior to this, catches across the entire lake hovered around 100 tons, even reaching 200 tons in some years. In 1997, fishing forecasts were around 4-5 tons.

Causes and Motivations Behind the Alborella Decline

What are the causes of this phenomenon? While the Ministry of Environment has acknowledged that the issue exceeds its direct jurisdiction, it has nonetheless addressed the matter based on information provided by the Province of Verona. The ministry confirms that alborella has experienced significant decline starting from 1995.

Although in the past the species showed periodic fluctuations in population density, never before had such a sharp decrease been observed…

The causes behind this situation in Lake Garda are still unknown, although it is not hard to hypothesize that they are linked to altered balances among the various fish species occupying the same ecological niche and to changed environmental conditions.

There is skepticism about attributing the cause to predators such as pike and perch, which were indeed present in greater numbers in the past compared to today.

The quality of water has come under scrutiny; it is good and does not appear to create problems, nor do the lake levels. Among the potential disturbances, phytoplankton or mucilage are cited, which could cover and suffocate eggs on shallow bottoms.

Furthermore, the increased presence of waterfowl that feed on the eggs is considered, by experts, a minor cause.

Instead, the Ministry’s report emphasizes the rapid increase of vimba as a key factor, which, according to the minister’s response—quoting directly—”is causing an imbalance in the Garda ecosystem.”

The species most affected are the carpione and perhaps the alborella, which partly shares the same type of diet.

Moreover, the aola is not suitable for restocking initiatives, and measures to contain its decline are currently being evaluated.