42 SEPTEMBER 2013 • WORLD AQUACULTURE • WWW.WAS.ORG of the Danube River. Aquaculture ponds enhance the population density of otters, which leads to migration and recolonization of areas once inhabited by otters. Now, the total population of otters in Lower Austria is roughly 300 to 500 individuals (Kranz and Polednik 2008). In addition to examination of the otter population by spraints and tracks, some information about the presence and distribution of otter can be gained from the reports of damage in carp ponds (Fig. 3), undoubtedly caused by otter. Northern Austria contains more than 1,800 ponds within 4,600 km2. The recovery FIGURE 2. Carp harvesting in autumn from a pond in Lower Austria near the border with the Czech Republic (Photo: Federal Agency for Water Management). FIGURE 3. Common carps killed by otters at a wintering pond (Photo: Federal Agency for Water Management).
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