Description and characteristics
The zander (Sander lucioperca, also known as Stizostedion lucioperca) is a large predatory fish with an elongated, laterally compressed body. It has large, characteristic eyes for low-light hunting and sharp teeth. The colouration is grey-green on the back and silvery on the flanks, with light olive mottling. The most distinctive features are the small, rough scales and a well-marked lateral line.
Habitat and distribution
The zander prefers clear, relatively deep water with hard bottoms, but is also found in the lakes, arms and canals of the Danube Delta. It avoids very turbid or densely vegetated waters, looking for areas where it can hunt schooling fish efficiently. It is sensitive to water quality and oxygen content.
Diet and behaviour
It is a piscivorous predator feeding almost exclusively on fish (bleak, roach, bream, perch, etc.). Thanks to its excellent vision, it frequently hunts at dusk and at night, detecting prey at long distances. It often lives solitarily or in small groups.
Reproduction
Spawning takes place in spring when the water temperature reaches 10–14°C. The female lays eggs on hard bottoms, vegetation or roots, disguising them for protection. Growth is fast, and zander reaches sexual maturity at about 3–4 years.
Economic and ecological importance
The zander is one of the most appreciated predatory fish of the Danube Delta, both for sport and professional fishing. Its flesh is white, firm and highly prized. Ecologically, it controls prey fish populations.
Threats and conservation
The main threats are pollution, overfishing and habitat alteration. Protection measures include catch limits, legal minimum sizes and protection of spawning areas.
Fishing and legal minimum size
Being a large predator, the zander is a premium catch for sport anglers. In the table of minimum legal sizes, the zander (Stizostedion sp.) has a minimum legal size of 40 cm.
Conclusion
The zander is an example of a top predator contributing to the balance of the aquatic ecosystems of the Danube Delta, while also representing a valuable resource for local communities.