| Popis: |
Over the past few centuries, sturgeons have experienced decline and, in some cases, extinction worldwide caused primarily by habitat loss stemming from human activities and overfishing. The vulnerability of sturgeons to climate change and anthropogenic impacts is associated with their life characteristics, e.g., long life span, slow growth, late maturation, and specific spawning habitat requirements. Acipenser oxyrinchus Mitchill inhabited the Baltic Sea from at least 5,000 years before the Common Era until the twentieth century. It spawned in Latvia rivers and migrations during the Bronze Age and Middle Ages were intense. As early as the eighteenth century, single sturgeon catches are found in records, and these were identified as extraordinary cases. Although fisheries in river spawning grounds can lead to stock decline, the decline of sturgeons in Latvian waters was more likely determined by climate change, probably cooling or the so-called Little Ice Age that lasted from 1550 until 1850. Our records suggest that at the end of seventeenth and the beginning of the eighteenth centuries, the Northern border of sturgeon distribution moved southward. Latvian marine and freshwaters become the northern border of the species’ areal, while it was still fished in Poland and Germany before its complete extinction in the twentieth century. |
