status: Endangered, IUCN
Description and biology
The Danube salmon, also known as the Huchen huchen, is the largest member of the salmon family. It can grow to almost 6 feet (1.8 meters) long and weigh 155 pounds (70 kilograms). It has a slender, cigar-shaped body. Its broad mouth contains a dense arrangement of teeth. This fish is highly predatory, feeding on fish, amphibians, reptiles, waterfowl (water birds), and small mammals.
Male Danube salmons become sexually mature at the age of four; females become sexually mature a year later. In the spring, females spawn (lay eggs) on the gravel bottoms of mountain rivers. After hatching, the young salmons develop very fast. After one year, they measure about 5 inches (12.7 centimeters) in length; by the end of their second year they have grown to almost 12 inches (30.5 centimeters) in length.
Habitat and current distribution
The Danube salmon was common in almost all rivers of the Danube watershed (the entire region drained by the Danube River). The salmon now breeds and spawns in only a few rivers in Austria, the Czech Republic, Slovakia, and Germany. It is found elsewhere in its range in only fragmented populations.
Danube salmons prefer cold, freshwater streams rich in oxygen and containing both rapid sections and deep pools lined with pebbles.
History and conservation measures
The greatest threat to the Danube salmon is the destruction of its habitat. Throughout its range, dams and canals have been built, preventing the fish from swimming to spawning grounds. Its habitat has been poisoned in many areas as sewage and industrial wastes have been pumped into rivers and streams. The runoff of pesticides from nearby farms has also poisoned many waterways.
Overfishing is a secondary threat to this salmon. Even though it cannot be taken without a permit and the fishing season has been shortened, the salmon's numbers continue to decline.
To help save the Danube salmon from extinction, conservationists urge that sewage dumping and pesticide use be controlled throughout the fish's range.