Lake Sturgeon, Acipenser fulvescens
Identifying Characteristics: (Native Fish) A notable characteristic is the five rows of bony plates (scutes) that are well developed in young fish but less distinguishable in adults. The scutes of young fish feel prickly and provide protection during vulnerable life-stages but become smooth in adults when the protection is no longer necessary. Lake Sturgeon have a large protrusible, suctorial mouth on the bottom side of the head with four barbels in front of the mouth and beneath the snout. The barbels are sensory organs that assist the sturgeon in finding prey on the river and lake bottoms. Lake Sturgeon have a single dorsal fin located far back near the caudal (tail) fin. The tail is heterocercal with the upper lobe much larger than the rounded lower lobe. Lake Sturgeon have scales but not the cycloid scales associated with most bony fishes, rather they are covered by the much stronger ganoid scales. Juvenile Lake Sturgeon are a sandy brown color with black mottling and spots, while adults are olive-brown to grey with white underneath.
Lake Sturgeon inhabit large river and lake systems primarily in the Mississippi River, Hudson Bay and Great Lakes basins. This species has and continues to represent an important biological and cultural component of the Great Lakes ecosystem. By the early 1900's many populations of Lake Sturgeon throughout their range had been greatly reduced or extirpated as a result of overfishing, habitat loss, the construction of dams and pollution. Lake Sturgeon are listed as a threatened species in Michigan and are either threatened or endangered in 19 of the 20 states within its original range in the U.S. This ancient family of fishes has been recognized since the Upper Cretaceous period (136 million years ago), at a time when dinosaurs were at the height of their development. Lake Sturgeon have retained primitive internal structures such as a cartilaginous vertebrae and a notochord, instead of calcified bone as found in modern fish.
Lake Sturgeon are the only sturgeon species endemic to the Great Lakes basin and are the largest freshwater fish indigenous (native) to that system. Lake Sturgeon often occupy nearshore habitats but have also been found in deep, offshore water. Lake Sturgeon are benthivores (meaning they eat prey from the bottom of waterbodies), feeding mostly on small invertebrates such as insect larvae, crayfish, snails, clams and leeches.
Life history characteristics of Lake Sturgeon are unique with respect to other Michigan fishes. Sexual maturity in females is reached between 14 and 33 years, most often from 24 to 26 years and 12 to 17 years for males. Generally, female Lake Sturgeon spawn once every three to seven years while males spawn every one to four years. Spawning occurs on clean, gravel shoals and stream rapids from mid-April to late May in preferred water temperatures of 55 to 64 degrees F. Female Lake Sturgeon may lay 4,000 to 7,000 eggs per pound of fish. The typical life-span of Lake Sturgeon is 55 years but individuals over 100 years old have been found. The current state record for a legally harvested Lake Sturgeon is 193 pounds taken from Mullett Lake (Cheboygan County). Sturgeon greater than 300 pounds have been observed in the Great Lakes Basin.
Habitat selection by Lake Sturgeon varies widely throughout their range and environment they inhabit. Some adult Lake Sturgeon have been found to remain in a small territory during the summer months, while others have been observed long distances from their original capture site one year later. Adult sturgeon are known to intermix in the Great Lakes during non-spawning periods, but habitually return to spawn in streams where they were born (homing behavior), often migrating long distances up rivers in the spring. After hatching, some young Lake Sturgeon have been observed to remain in their natal rivers for their first summer of life. Because of this homing ability many of the sturgeon populations in the Great Lakes Basin have been found to be genetically distinct.
Efforts are currently underway in the Great Lakes Basin to restore sturgeon populations and reclaim the historic connection between this fish and people. Since the early-2000's Federal, State and Tribal agencies have partnered in rehabilitating Lake Sturgeon through the use of Streamside Rearing Facilities. In these facilities sturgeon eggs and larvae are reared in the waters which they will be released with hopes the fish will imprint and home back to their natal waters. In each facility sturgeon are reared to a size where they are likely to survive and be less vulnerable to predators. Each year thousands of sturgeon are released during public ceremonies and gatherings.
Learn more about Lake Sturgeon in Michigan on their dedicated website: www.michigan.gov/sturgeon.
Lake Sturgeon graphic courtesy of Joseph R. Tomelleri and copyrighted.