Lake sturgeon
Lake Sturgeon (Acipenser fulvescens )
The lake sturgeon (Acipenser fulvescens ) is a species from the genus of sturgeon (Acipenser ), which occurs in North America in rivers and lakes. It is fished commercially and by sports fishermen.
Features
The Lake Sturgeon has the typical elongated body of the sturgeon. The snout carries four barbels smooth and is pointed in young animals, but with increasing age duller and wider. Along the body run five rows of bony plates, one along the back, one on mid-height of the edge and one at the edge of the abdomen. In young animals, the plates are large and designed to sharply pointed hook, the skin is rough. With age, the scales blunt and shrink to almost complete disappearance, the skin becomes smoother. The first plate of the back row touches the top plate. The back row has 9 to 15 plates on which side rows 29 to 42 and the ventral rows 7 to 12 One to two bone plates can also be found behind the dorsal and anal fins, but both are not accompanied by bone plates. Juveniles are reddish brown and have irregular black spots on. Adult animals are greenish - olive-brown or greyish without drawing. The dorsal fin has 35 to 45, the anal fin 25 to 30 soft rays on. The arches of the gills Reuse carry 25 to 40 rays. Adult animals reach a length of 1.80 meters and an average of one to a maximum of 2.7 meters and a weight of up to 125 kg. The age limit should be up to 152 years.
Occurrence
The lake sturgeon comes in Saint Lawrence River, the Great Lakes, Lake Champlain, the Hudson Bay before, the Saskatchewan River and the river system of the Mississippi River to North Louisiana and South -South Dakota. Between the stocks in the Great Lakes and Western Canada and those of the Mississippi probably no exchange takes place.
Way of life
The species lives at the bottom of lakes and large rivers. It penetrates into brackish water occasionally, but not the salt water before. Food is tracked at the base using the barbels. Lake sturgeon are a little finicky omnivores that feed among other insects, molluscs, fish and worms. Partially hikes of more than 1000 kilometers to be made between different feeding and spawning grounds.
The mating season begins in the spring when the water temperature 9-15 ° C is reached. While the males reproduce every two to four years, the females spawn only once every three to seven years. The up to 7,000,000 eggs per female are stored in stony shore areas of lakes and rivers. Sexual maturity is reached by males 14 to 16 years old and about 114 cm in length, females with only 24 to 26 years and 140 cm length.
Use and threats
While the catch of lake sturgeon is banned in the USA for commercial purposes, the species is fished in Canada for their meat and caviar. The sport fishing is permitted in some U.S. states at certain times. Because of the long generation times of the species is prone to failure. In the CITES Convention, the lake sturgeon is listed in Annex II, the IUCN estimates the stock is currently a no impairment (Least Concern ).