These large fish can take up to 18 years to reach sexual maturity and even then will only spawn once in every 2 to 4 years (2). Adults migrate upstream in the spring or autumn to spawn in shallow pools; a single female can produce between 300,000 and 7.5 million eggs, which are attached to stones on the pool floor (2). Once they have emerged, juveniles migrate downstream to the sea (2).
The fleshy barbels in front of the mouth are used to search for prey on the seafloor and riverbed (5); juveniles feed mainly on small invertebrates whereas adults tend to consume fish such as anchovy, gobies and herring (2). Belugas spend the majority of their time in the lower reaches of the water column, near to the substrate (3).