ObsBio, the collection of individual biological parameters such as size, weight, sex, age are necessary data to know by elevation, the share of the populations in the recruitment of young fish, in the natural mortality and in the mortality by fishing

The number of inhabitants according to official statistics by age group (<20 years, >=65 years, >=80 years) and by administrative entity (region, province, district and municipality) for Flanders and the Brussels Capital Region

The number of inhabitants according to official statistics by age group (<20 years, >=65 years, >=80 years) and by administrative entity (region, province, district and municipality) for Wallonia