The emergence of the invasive perch fish, which is not native to this region, has been detected in the watercourses of Pljevlja, suggesting a direct human impact.

This statement comes from Milorad Mitrović, the executive director of the Breznica Ecological Society.

“A recent unexpected catch of perch at Lake Otilovići by a fisherman from Pljevlja caught the attention of local anglers, generating significant concern among them and other nature enthusiasts. The sighting of perch (Sander lucioperca), a predatory species, in Lake Otilovići and Lake Borivičko, along with its recent reported presence in the watercourses of Ćehotina, Breznica, and Vezišnica, as well as its tributaries, has alarmed fishermen, biologists, and local residents alike. This species is not naturally found in these waters, and previously, it was not part of the fish population in these ecosystems. The perch, being an allochthonous species, indicates human intervention—either through illegal introduction or poor management practices lacking proper ecological evaluations,” Mitrović stated.

He warns that the introduction of perch to these habitats could endanger native and already vulnerable fish species, such as brown trout, brook trout, grayling, and roach, which are sensitive to ecosystem changes and the introduction of new predators.

“Perch primarily preys on other fish, and its predatory nature, adaptability to various environments—including murky waters—and its high reproductive rate make it a formidable competitor for food and space. Younger individuals of native fish, which are easy targets for perch, are especially threatened, particularly in low-flow and eutrophic conditions of lake systems. Such an introduction—if not properly managed or scientifically validated—constitutes an ecological crisis. It may stem from illegal stocking by individuals, often motivated by sport fishing without understanding the ecological balance, or from failures in oversight by managing authorities. In either scenario, relevant institutions such as the Water Administration of Montenegro, the Ministry of Agriculture, Water Management and Forestry, and the managing body for fishing areas, SRK ‘Lipljen’, must act promptly to identify responsibility, curb the spread of this invasive species, and implement control and eradication measures,” the noted ecologist asserted.

Moreover, he emphasizes that the introduction of invasive and non-native species into drinking water sources poses a direct risk to the environment and public health.

“The law imposes penalties for both intentional and unintentional actions of this nature, acknowledging the importance of conserving natural resources. Such offenses should be treated with utmost seriousness, particularly in sensitive areas like drinking water sources. The Criminal Code of Montenegro explicitly outlines—within Articles 303 and 312a—criminal acts against the environment, making it a punishable offense to introduce, spread, cultivate, reproduce, transport, use, exchange, or market invasive species designated as such by the relevant authorities. We express our grave concern regarding the presence and spread of this predator in our watercourses and urge all relevant institutions to initiate biological monitoring of lakes and tributaries to assess the population of this invasive species, engage experts in formulating a remediation plan, identify those responsible for this introduction, and enforce penalties against them. Furthermore, clear protocols must be established for future stocking and the protection of native species,” Mitrović concluded.

He also reminisces about how, until the end of the last century, the waterways of Pljevlja were among the most biodiverse and species-rich in Europe, as documented during the Austro-Hungarian period. However, over the past fifty years, these ecosystems have been severely depleted and transformed into profit-driven ventures involving exploitation and destruction.

“It’s time to halt the longstanding practices of destruction and mismanagement, and to move towards better protection against such reckless and illegal actions driven by irresponsible and uninformed individuals, which can lead to unpredictable and lasting consequences,” Mitrović emphasized.

News