Family ACIPENSERIDAE 



THE STURGEON FAMILY 



The sturgeons are the remnants of an ancient and primitive group of 

 fishes in which the primitive cartilaginous skeleton is retained and bony 

 plates have appeared in the skin. Sturgeons are found throughout north- 

 ern Europe, Asia, and North America. Some species are marine, others 

 ascend rivers periodically to spawn, and others are landlocked. In North 

 America two species are found on the Atlantic Coast. Two other 

 species occur on the Pacific Coast, one of which, Acipenser transnion- 

 taniis Richardson, has been reported as weighing nearly a ton. In the 

 Mississippi Valley there are two species of sturgeons, both present in 

 Minnesota and neighboring states. These species are the rock, or lake, 

 sturgeon and the hackleback, or shovelnose, sturgeon. 



Sturgeons are distinguished by their shovellike snout, on the under 

 side of which is a protractile, subterminal mouth with thick papillose 

 lips extensible for sucking up food. Four barbels in a transverse row are 

 present under the snout, anterior to the mouth. No teeth are present 

 except in the very young. The internal skeleton is composed of cartilage 

 and retains a well-developed notochord. The head is covered by bony 

 plates, and rows of shieldlike plates occur on the sides. The gills are four 

 in number. There are no branchiostegal rays; the gill-membranes are 

 joined to the isthmus (p. 57) . The dorsal and anal fins are inserted far 

 back. The tail or caudal fin is heterocercal. 



Key to Common Species of Family ACIPENSERIDAE 



Snout pointed, sub-conic; small spiracle present; lateral bony plates not meeting 



on tail Rock Sturgeon, Acipenser julvescens, Rafinesque 



Snout rounded, shovel-shaped, depressed above; spiracle absent; lateral bony 



plates meeting and covering tail 



Hackleback, Scaphirhynchus platorynchus (Rafinesque) 



GENUS Acipenser Linnaeus 



The genus Acipenser is represented in North America by five species, 

 most of which are marine and anadromous, i.e., ascend rivers to 

 spawn. These fishes are characterized by a small spiracle and by a 

 short, pointed snout. Many of them reach a very large size. 



ROCK STURGEON (Lake Sturgeon, Red Sturgeon, Nah-way 

 of the Red Lake Chippewas) 



Acipenser julvescens Rafinesque 



The rock, or lake, sturgeon (Figure 4A) is the largest of the native 

 fishes of Minnesota and neighboring states. Individuals weighing over 



75 



