Sturgeons are bottom-feeders whose diet revolves around invertebrates: worms, insect larvae, crustaceans, mollusks, and occasionally small fish. Because there are roughly 27 recognized sturgeon species spread across rivers, lakes, estuaries, and coastal ocean shelves in the Northern Hemisphere, the specifics vary quite a bit depending on which species you’re looking at and where it lives. What ties them all together is a shared set of feeding tools and a benthic lifestyle, meaning they cruise along the bottom of whatever body of water they inhabit, rooting through sediment for prey they detect largely by touch, taste, and even electrical signals rather than by sight.
How Sturgeons Find and Eat Their Food
To understand what sturgeons eat, it helps to understand how they eat, because their anatomy limits and directs their diet in ways that set them apart from most other large fish. A sturgeon’s mouth sits on the underside of its head, behind a set of four fleshy whisker-like projections called barbels. Those barbels are packed with taste buds and tactile sensors that drag along the bottom as the fish swims, essentially scanning the sediment for anything edible. When the barbels detect prey, the sturgeon deploys a mouth that is highly protrusible, meaning it extends downward like a tube to vacuum up sediments containing clams and other buried organisms.1ResearchGate. Ingestion in Fish The fish doesn’t bite or chew in any conventional sense. It sucks in a mouthful of substrate, sorts out the edible items, and expels the rest through its gills.
Sturgeons also possess another sensory system that most people don’t associate with fish: electroreception. Sturgeons belong to a group of ancient fishes that can detect weak electric fields in the water using specialized organs called ampullae, structures similar to those found in sharks and rays.2ResearchGate. The functional roles of passive electroreception in non-electric fishes Every living organism produces faint bioelectric signals, and sturgeons can pick up on those signals to locate prey buried under mud or sand, even in murky or dark water where vision is useless. This makes them remarkably effective at finding food in environments where other predators would struggle.
The combination of barbels, electroreception, and a vacuum-like mouth means sturgeons are superbly adapted for a specific ecological role: extracting small, soft-bodied creatures from soft substrates. They are not pursuit predators. They don’t ambush prey from cover. They methodically work their way across the bottom, and the composition of whatever invertebrate community lives in that sediment is essentially the sturgeon’s menu.
What Young Sturgeons Eat
A sturgeon’s diet shifts substantially as it grows, and the youngest fish eat a markedly different set of organisms than adults do. Research on first-feeding larval and young-of-the-year white sturgeon in the lower Columbia River found that even fish as small as 15 millimeters fed primarily on tiny amphipods, specifically a genus called Corophium.3Northwest Science. Diet of first-feeding larval and young-of-the-year white sturgeon in the lower Columbia River As the young sturgeon grew, amphipods became even more dominant in the diet, and the size of amphipods they consumed increased in step with their own body length. At the very onset of feeding, the smallest larvae also ate copepods, midge larvae (chironomids), and other tiny fly larvae and pupae, presumably because these were the smallest prey items available and matched the gape size of a newly hatched sturgeon.
This pattern of starting with the tiniest available invertebrates and progressively adding larger prey is common across sturgeon species. It’s a function of mouth size, suction power, and the ability to process different types of prey. A larval sturgeon simply cannot vacuum up a large worm or a clam, so it subsists on what fits. As the fish matures and its protrusible mouth becomes more powerful, the dietary options widen considerably.
Freshwater River Diets
For sturgeon species that spend most or all of their lives in rivers, aquatic insect larvae are the dietary backbone. Shovelnose sturgeon, one of the smaller North American species, provide a clear example. A study of shovelnose sturgeon in the lower Platte River in Nebraska found that aquatic insect larvae and nymphs made up more than 99 percent of the diet by number.4Journal of Applied Ichthyology. Diet composition and feeding patterns of adult shovelnose sturgeon (Scaphirhynchus platorynchus) in the lower Platte River, Nebraska, USA Midge fly larvae from the family Chironomidae dominated overwhelmingly, composing roughly 97 to 98 percent of the diet across two years of sampling. Beyond chironomids, the fish also ate mayfly nymphs and caddisfly larvae, but in much smaller quantities. Other aquatic insects, terrestrial invertebrates, and fish showed up only rarely.
The specific chironomid genera that dominated the shovelnose sturgeon diet are ones typically found on sandy substrates, which tells researchers something about where these fish are actually foraging. The sturgeon aren’t randomly grazing across the river bottom; they are preferentially working sandy habitats where their preferred prey is most abundant. This makes habitat type a major driver of diet composition. A sturgeon living over gravel or cobble would encounter a different invertebrate community than one foraging over sand or silt, even within the same river.
What Sturgeons Eat in Estuaries and the Ocean
Sturgeons that move between freshwater and saltwater, or that spend substantial time in coastal marine environments, shift to a diet dominated by marine invertebrates. The difference from a freshwater river diet can be dramatic. Instead of insect larvae, marine-phase sturgeons rely heavily on polychaete worms, which are segmented worms that live in tubes or burrow through marine sediment.
Studies of Atlantic sturgeon feeding on the intertidal mudflats of the Bay of Fundy found that polychaetes were the single most important prey group by occurrence, abundance, and weight.5Journal of Applied Ichthyology. Feeding ecology of Atlantic sturgeon, Acipenser oxyrinchus oxyrinchus Mitchill, 1815 on the infauna of intertidal mudflats of Minas Basin, Bay of Fundy Several genera of polychaetes appeared in the stomachs, including bloodworms. Crustaceans like amphipods and mysid shrimp played a secondary role, and a handful of other organisms, including sand shrimp and isopods, turned up in trace amounts.
Research off the central New Jersey coast painted a similar picture for the same species. Polychaetes were again the primary prey group, though an isopod species was the single most important individual prey item consumed.6Transactions of the American Fisheries Society. Food habits of Atlantic sturgeon off the central New Jersey coast Mollusks and fish contributed very little. The study also noted seasonal variation in how important different prey groups were: the relative contribution of polychaetes, isopods, and amphipods in the diet shifted over the course of the year, likely tracking seasonal changes in prey availability on the seafloor.
The common thread across marine settings is that sturgeons eat whatever soft-bodied or small-shelled invertebrates are living in or on the sediment. They don’t specialize on one prey type so much as they specialize on a foraging strategy: vacuuming the bottom. The prey composition then follows from whatever community of organisms happens to live in that particular patch of mud, sand, or silt.
When Invasive Species Rewrite the Menu
One of the more striking findings in recent sturgeon diet research is how quickly these fish can adapt their feeding when new food sources appear. Lake sturgeon in the Great Lakes region have traditionally eaten a mix of invertebrates, but the arrival of round goby, an invasive fish from Eurasia, changed things in a big way. A study of lake sturgeon in the Niagara River and western Lake Ontario found that round goby had become the single most important prey item, making up 86 percent of the diet by weight.7Biological Invasions. Invasive species alter ontogenetic shifts in the trophic ecology of Lake Sturgeon (Acipenser fulvescens) in the Niagara River and Lake Ontario The researchers confirmed this dietary shift using chemical signatures in the sturgeon tissue, which matched what you’d expect from a diet dominated by goby rather than traditional invertebrate prey.
This is a genuinely unusual finding for a group of fish generally characterized as invertebrate specialists. Round gobies are small, bottom-dwelling fish that happen to occupy the same benthic habitats sturgeons forage in, so from the sturgeon’s perspective, they’re just another bottom item to vacuum up. The researchers concluded that this dietary shift may actually benefit lake sturgeon population growth, since gobies are energy-dense compared to most invertebrate prey. It’s an ironic twist: an invasive species that has caused serious ecological damage to many native fish communities appears to be providing a caloric windfall for a native species that is itself endangered or threatened across much of its range.
White sturgeon in the Pacific Northwest have also experienced changes in the prey community thanks to invasive species. The introduction of non-native invertebrates and the displacement of native benthic organisms have altered the composition of what’s available on the bottom, and white sturgeon diets have shifted in response.8Marine Ecology Progress Series. Ancient fish and recent invaders: white sturgeon Acipenser transmontanus diet response to invasive-species-mediated changes in a benthic prey assemblage Whether these changes ultimately help or hurt the sturgeon depends on whether the new prey community is as nutritionally valuable as the old one.
Feeding Sturgeons in Aquaculture
Sturgeon aquaculture is a significant global industry, driven largely by the production of caviar but also of sturgeon meat. Feeding captive sturgeon well enough to support fast growth and healthy development requires replicating, at least nutritionally, what wild sturgeons get from their natural diet. Since wild sturgeon eat a protein-rich mix of invertebrates, formulated aquaculture feeds tend to be heavy on animal protein sources.
A formulated diet tested for juvenile lake sturgeon included a mix of menhaden fishmeal, casein, squid meal, wheat gluten, and a blend of soy oil, fish oil, and lard, among other ingredients.9North American Journal of Aquaculture. Evaluation of Formulated Feed for Juvenile Lake Sturgeon Based on Growth Performance and Nutrient Retention The feed also incorporated algal powder, vitamin and mineral premixes, and binding agents. Getting the protein content and fat ratio right is critical because sturgeons in the wild are eating high-protein prey almost exclusively, and a captive diet that skimps on protein or provides the wrong fat profile can lead to poor growth, liver problems, or reduced immune function.
One challenge in sturgeon aquaculture is that very young fish often resist formulated pellets at first. In the wild, larval sturgeon transition from yolk-sac nutrition to live prey items like copepods and tiny insect larvae, and that initial feeding period can be difficult to replicate with artificial feed. Many hatcheries start larvae on live food such as brine shrimp or bloodworms before gradually weaning them onto pellets. Getting through that transition smoothly is one of the trickiest parts of raising sturgeon from eggs.
Why Habitat Quality Matters More Than Any Single Prey Species
Because sturgeons are generalist bottom-feeders rather than specialists dependent on one specific prey organism, the health of the invertebrate community in their habitat matters more than the presence of any single prey species. A river with clean sand substrates, moderate flow, and a diverse community of insect larvae will support shovelnose sturgeon. A coastal estuary with healthy mudflats and abundant polychaete populations will feed Atlantic sturgeon. Remove those habitats or degrade them, and the food base collapses regardless of which particular worm or insect is lost.
Dam construction, channel dredging, and pollution can all reduce or eliminate the benthic invertebrate communities that sturgeons depend on. Dams alter flow regimes and change sediment dynamics, often armoring the riverbed with coarser material that supports fewer of the soft-sediment invertebrates sturgeons prefer. Agricultural runoff can cause eutrophication and oxygen depletion in bottom waters, killing off the very organisms sturgeons need to eat. These habitat-level threats are arguably more dangerous to sturgeon populations than the loss of any one prey type, because sturgeons can switch among prey items as long as the overall invertebrate community remains intact.
Contaminants and the Cost of Eating From the Bottom
A bottom-feeding lifestyle comes with a downside: contaminants tend to accumulate in sediments, and sturgeons are constantly ingesting sediment along with their prey. Metals and persistent organic pollutants that settle into river or estuary mud get taken up by the small invertebrates living there, and when a sturgeon vacuums up those invertebrates, it ingests the contaminants as well. Research on endangered European sturgeon exposed to sediments from the Garonne and Dordogne rivers in France found that metals including cobalt, copper, iron, selenium, vanadium, and zinc accumulated in liver tissue over time.10ScienceDirect. Effects of metals and persistent organic pollutants on the fitness and health of juveniles of the endangered european sturgeon Acipenser sturio exposed to water and sediments of the Garonne and Dordogne rivers Muscle tissue tended to accumulate fewer metals than the liver, though arsenic concentrations in muscle increased over time under river-sediment conditions.
This bioaccumulation pattern has implications both for sturgeon health and for human consumers of sturgeon products. For the fish themselves, chronic exposure to contaminated sediments can impair growth, reproduction, and immune function. For people eating sturgeon meat or caviar, the question of what contaminants have accumulated in the fish’s tissues is a food safety concern, particularly for species harvested from industrialized waterways. The same feeding habits that make sturgeons ecologically fascinating also make them sentinels for sediment pollution: a sturgeon’s body essentially records the chemical history of the bottom it feeds on.
How Researchers Figure Out What Sturgeons Have Been Eating
Studying the diet of a large, long-lived, often endangered fish isn’t straightforward. You can’t simply catch and kill hundreds of sturgeons to check their stomach contents, especially when some species are protected. Researchers use a mix of traditional and modern methods. Stomach content analysis, where a fish is either sacrificed or has its stomach lavaged (flushed with water to extract contents without killing it), gives a direct snapshot of recently consumed prey but only captures what the fish ate in the last few hours or days. Prey items may also be partially digested and hard to identify.
Stable isotope analysis has become a valuable complementary tool. By measuring the ratios of certain chemical isotopes (particularly carbon and nitrogen) in sturgeon tissues, researchers can infer what the fish has been eating over longer time scales, from weeks to months depending on the tissue sampled. This approach was used alongside stomach content analysis in the lake sturgeon/round goby study mentioned above, where isotope signatures confirmed that gobies were a major long-term dietary component, not just an occasional meal. One practical question for this method is whether you can use a small fin clip instead of a plug of muscle tissue, since fin clips are less invasive. Research on lake sturgeon found that pectoral fin clips and dorsal muscle samples track each other reasonably well for both nitrogen and carbon isotope values, with the relationship for carbon improving substantially when lipids are chemically extracted from the samples first.11ScienceDirect. Non-lethal sampling of lake sturgeon for stable isotope analysis: Comparing pectoral fin-clip and dorsal muscle for use in trophic studies This means researchers can study sturgeon diets over time without harming the animals, which matters enormously for threatened populations where every individual counts.
Environmental DNA, or eDNA, is a newer frontier that may eventually allow diet studies from water samples or fecal material alone. For now, the combination of gut content analysis and stable isotope work provides the most complete picture of what these ancient fish are finding on the bottom.