How many different species of caviar are there in the world?
The sturgeon is a type of bony fish with long spindle-shaped bodies and 5 lateral rows of bony armor called scutes. Similar to sharks, they have a heterocercal tail fin and smooth, scaleless skin. The sturgeon has 4 mustache-like sensory organs called barbels that help them sense the movement of prey in dark, murky waters. As bentonite eaters, they suck shellfish, crustaceans, and smaller fish from the sea floor using their extensible, toothless mouths.
Most sturgeons are bottom feeding anadromes that spend most of their lives eating in river deltas and estuaries, migrating upstream only in the spawning season. Some species inhabit freshwater systems exclusively while others live in coastal marine environments with access to the open ocean. Sturgeons are native to subtropical, temperate and sub-arctic rivers, lakes and coasts of Europe, Asia and North America.
Sturgeon is one of the oldest fish species in the world. They are among the oldest remaining members of the group of bony fish (Osteichthyes) with their evolution attributable to the early Triassic period, almost 250 million years ago. Sturgeons are referred to as "primitive fish" because their morphological characteristics have remained relatively unchanged since the earliest fossil records.
Sturgeon is the largest, longest-lived and slow-growing freshwater / anadromous fish in the world. While some sturgeon species only grow to a couple of feet in length, others can get quite large, usually ranging from 7 to 12 feet and up to 1,000 pounds. The largest sturgeon in the world, a female beluga, was nearly 3,500 pounds and 24 feet long. The life expectancy of a sturgeon in the wild is around 60 years, with the oldest recorded specimens being at least twice that age. In addition, they mature to adulthood much slower than other fish, taking an average of 10 years before reaching maturity.
Today, the sturgeon is one of the most valuable and sadly endangered fish in the world. Their precious eggs are the only ones acceptable to make the delicacy of "real caviar". This expensive luxury food has made the sturgeon a target for both legal commercial fishing and illegal poaching operations looking to profit from their precious eggs. Overexploitation of sturgeon species has resulted in the entire Acipenseridae family being considered endangered, making them the most endangered species group in the world. Because sturgeons have remained unchanged for hundreds of millions of years, they are also particularly vulnerable to the latest threats of pollution and habitat destruction. With their slow growth rate, it can take many years for sturgeon populations to recover to their wild habitat, and despite a slight resurgence for some species in recent years, the family as a whole remains highly threatened.
Paddlefish are closely related to the sturgeon, but technically they are not part of the sturgeon family. Paddlefish and sturgeon have common origins dating back 300 million years. Both sturgeon (family Acipenseridae) and paddlefish (family Polydontidae) have the structural traits of primitive fish: scaleless skin, heterocercal tail fin, bony features, a cartilaginous endoskeleton, no vertebral center, spiral valve intestines, and a single four heart chambers with a conical infundibulum pocket (conus arteriosus).
Instead of shields and barbels, the paddlefish developed a bony skull and a long, paddle-like snout. Most of the head and rostrum are covered with electroreceptors that help locate food. Having poor eyesight, paddlefish use a series of sensory pores extending from the gills to the tip of the snout to detect prey movement and navigate the depths of muddy rivers. Their beaks are equipped with ampoule hair cells that can pick up electrical signals from even the smallest marine creatures. While Chinese paddlefish have a protruding mouth, eat fish and bottom prey like most sturgeons, American paddlefish are filter feeders with diets consisting primarily of zooplankton, small insects, larvae, and young fish.
Paddlefish, sturgeon, African teacup, and canefish are the world's three oldest species of ray-finned fish (Actinopterygii). These "relic fish" and others such as shortfin, gar, lungfish and some shark species exhibit the same physiological traits as their ancestors from the Mesozoic era.
Paddlefish and sturgeon are the only remaining Acipenseriformes and are some of the last condi fish on our planet. Sturgeon, paddlefish, and a large number of relatives of the Chondrostei suborder dominated water systems during the Triassic and early Jurassic periods with some of the greatest diversity of any group of species at the time. Most of the Condorites became extinct in the late Cretaceous; the only survivors are the paddlefish, the sturgeon and the teacup.
Just like sturgeon and teacup, paddlefish has remained virtually unchanged over the past 70 million years. This, coupled with the growing value of paddlefish meat and roe in specialty markets, has resulted in wild paddlefish populations facing the same modern threats (overfishing and environmental collapse) that have endangered wild sturgeon populations. .
There are 27 species of Acipenseriformes living today. This is made up of 2 species of paddlefish and 25 true species of sturgeon; about 9 species of sturgeon and 1 species of paddlefish are native to North America. The exact number of sturgeon, sturgeon subspecies, and sturgeon hybrids surviving in their natural habitats remains unknown. The IUCN believes that 85% of the Acipenseridae family is in danger of extinction and that up to 4 species may already be extinct.
The table below shows all accepted species and subspecies for a total of 28 different sturgeons: Acipenser baerii (Siberian) is divided into 3 subspecies, oxyrinchus is separated into 2 subspecies and Acipenser multiscutatus (Japanese) has been removed because it is synonymous with Acipenser schrenckii ( Amur) commonly accepted as the same fish. As it is difficult to obtain exact data on how many fish of each species exist in the wild, IUCN hazard levels are sometimes scrutinized for inaccuracy. Worldwide today, fewer than half of the 26 sturgeon species are fished or bred commercially for their caviar. Even in this modern age, with most of the sturgeon caviar coming from fish eggs raised on farms of only 10-12 different species, most of the Acipenseridae family is at risk of extinction in the wild. Only in regions where sturgeon species are properly regulated and protected from man-made threats do they begin to recover slowly.
These 25 sturgeon species are grouped into four genera: Acipenser, Huso, Scaphirhynchus, and Pseudoscaphirhynchus. Each genus consists of mostly endangered specimens. Of the 28 true species and subspecies of sturgeon, 18 are classified as "critically endangered", 3 as "endangered", 3 as "vulnerable", 2 as "near threatened" and 2 as "low risk / least concern".
The two closely related non-sturgeon species, Polyodon spathula (American paddlefish) and Psephurus gladius (Chinese paddlefish) are also endangered. The American paddlefish population, listed as "vulnerable," has benefited from US regulation and sustainable fishing practices in recent decades. However, the "endangered" Chinese paddlefish has not received similar protections, has not been seen in the wild for decades and is thought to be extinct. The fossil record indicates that another 4 different species of paddlefish went extinct in the last era.
Of the remaining 25 estimated wild sturgeon species and 2 wild paddlefish species, none have been definitively listed as having a stable population. Looking ahead, many scientists and government officials are working hard to protect local Acipenseriformes so their numbers can increase and prevent their extinction.
Kingdom: Animalia (animals) | Phylum: Chordata (chordates) | Subphylum: Vertebrata (vertebrates) | Class: Actinopterygii (ray-finned fish) | Subclass: Chondostrei (paddlefish, paddlefish sturgeon) Order: Acipenseriformes (paddlefish, sturgeon) | Sub order: Acipenseroidei ...
Genus: Acipenser | Species: Acipenser naccarii (Adriatic), Acipenser schrenckii (Amur / aka Japanese {Acipenser multiscutatus}), Acipenser oxyrinchus oxyrinchus (Atlantic), Acipenser sinensis (Chinese), Acipenser sturio (Common), Acipenser nudiventris (Fringebenser medic green) ), Acipenser oxyrinchus desotoi (Gulf), Acipenser fulvescens (Lake), Acipenser persicus (Persian), Acipenser gueldenstaedtii (Russian), Acipenser mikadoi (Sakhalin), Acipenser brevirostrum (Shortnose), Acipenser baerii [subspecies siberian) , Acipenser baerii baicalensis (Baikal), Acipenser baerii stenorrhynchus (River Lena)], Acipenser stellatus (starry), Acipenser ruthenus (Sterlet), Acipenser transmontanus (white), Acipenser dabryanus (Yangtze).
Genre: Huso | Species: Huso huso (Beluga), Huso dauricus (Kaluga).
Subfamily: Scaphirhynchinae
Genus: Scaphirhynchus | Species: Scaphirhynchus suttkusi (Alabama), Scaphirhynchus albus (Pale), Scaphirhynchus platorynchus (Shovelnose).
Genus: Pseudoscaphirhynchus | Species: Pseudoscaphirhynchus kaufmanni (Amu Darya), Pseudoscaphirhynchus hermanni (Dwarf), Pseudoscaphirhynchus fedtschenkoi (Syr Darya).
Family: Polydontidae (paddlefish)
Genus: Psephurus | Species: Psephurus gladius (Chinese paddlefish)
Genre: Polydon | Species: Polydon spathula (American paddlefish)
