Acipenser

Acipenser is a genus of large, ancient fishes in the family Acipenseridae, commonly known as sturgeons. The genus is distributed across the northern hemisphere, including Europe, Asia, and North America. Many Acipenser species are diadromous, moving between rivers and seas as part of their life cycles, while others remain predominantly in freshwater.

Morphology and biology: Sturgeons have elongated bodies, a long rostrum, and a mouth located on the underside. They are covered with bony scutes rather than typical scales, and their skeleton is largely cartilaginous. Their tails are heterocercal, and they possess sensory barbels near the mouth used to detect prey.

Biology and ecology: Sturgeons are long-lived and late-maturing; ages of several decades are common. They spawn in large rivers or suitable tributaries, often migrating upstream to gravel or sandy bottoms. Eggs are adhesive and hatch into larvae that drift downstream. Diet consists of invertebrates, crustaceans, and occasionally small fish.

Conservation and human use: Sturgeons have long been harvested for meat and especially caviar, leading to severe population declines in many areas. They are now protected under national laws and international agreements (including CITES) in many regions. Conservation measures include fishing quotas, habitat restoration, dam removal or bypasses, and hatchery-based stocking to support wild populations.

Taxonomy and notable species: The genus comprises several dozen species, including Acipenser baerii (Siberian sturgeon), Acipenser sturio (Atlantic sturgeon), Acipenser oxyrinchus (shortnose sturgeon), Acipenser fulvescens (lake sturgeon), and Acipenser transmontanus (white sturgeon). The precise number and limits of species are subject to ongoing taxonomic revision.