Lake Sturgeon Early Life History

Lake Sturgeon eggs take between 5 and 14 days to hatch. Eggs and larvae are eaten by many other fish species, so newly hatched larvae avoid light and actively search for cover (between rocks or other hiding spots) on the water’s bottom. Larvae have a yolk sac on their belly which provides them with nourishment for 9-18 days after hatching. Around 14 days after hatching, larvae start to look like baby Sturgeon, and they typically begin to feed after 16 days. At this time, larvae begin to rise off the bottom at night to drift downstream to suitable ‘nursery areas’ which, in Manitoba, appear to be located in deep water with low to moderate water velocities.

Lake Sturgeon are most vulnerable to natural mortality during their first year (at this age they are called Young-Of-Year, or YOY). For successful reproduction, there needs to be suitable environmental conditions for spawning, egg fertilization, egg incubation, and larval drift. To transition from the yolk sac to feeding on their own the larvae must be able to find suitable foraging habitat and avoid being eaten while competing for food. Young that survive their first winter are pretty tough and many of these fish may live to become adults.

For a more detailed explanation, please refer to section 1.1.2 of the KSNC Stewardship Plan (2016) .

Lake Sturgeon Juveniles and Sub-Adults

In Northern Manitoba, most Lake Sturgeon less than 80 cm long and younger than 10 years old are immature. These juvenile and sub-adult Sturgeon can be found in a variety of habitats that offer them suitable currents, bottom types, and food resources. In the Nelson River, juvenile and sub-adult Lake Sturgeon have been caught strictly in deep (≥ 5 m) water habitats, similar to those where YOY sturgeon have been caught. In the Burntwood River (Manitoba), juvenile and sub-adult Lake Sturgeon have also been caught in deep-water habitats (8-17 m), in water velocities ranging from about 0.2-0.5 m/s, and over clay, gravel and sand substrates. York Factory First Nations and others have reported catching sub-adult sturgeon in relatively shallow habitat at the mouth of the Hayes River.

Juveniles are protected from predation by sharp bony scutes on their back and sides that make them difficult for other species to catch and eat.

For a more detailed explanation, please refer to section 1.1.3 of the KSNC Stewardship Plan (2016) .

Lake Sturgeon Over-wintering

During winter, juvenile, sub-adult and adult Lake Sturgeon generally occupy deep water habitat if it is available. In the Nelson River between Clark Lake and Gull Rapids, most adult Lake Sturgeon tagged with acoustic transmitters congregated in deep (> 8 m), low-moderate water velocity habitats in Gull Lake, but some overwintered in the river between Clark Lake and Gull Lake. In Stephens Lake, juvenile sturgeon were found most often in deep water habitat (> 10 m) with a silty bottom. In the lower Nelson River, Lake Sturgeon are known to over winter in Angling Lake, in the Nelson estuary near Jackfish Island.

Gilbert Beardy (York Factory First Nation) noted that “In the winters they (sturgeon) go all over the place feeding in the shallows.”

For a more detailed explanation, please refer to section 1.1.4 of the KSNC Stewardship Plan (2016) . 

Lake Sturgeon Foraging

As Lake Sturgeon grow, their dietary (food) preferences change. Age-0 Lake Sturgeon typically prefer aquatic macroinvertebrates (larger bugs) like dipterans (two-winged insects), trichopterans (caddis flies), ephemeropterans (may flies) and nematodes (round worms). Stomach contents of YOY Lake Sturgeon captured from the lower Nelson River by Jackfish Island were comprised primarily of amphipods (freshwater shrimp or scuds).

Juvenile Lake Sturgeon can eat larger food items (prey) from a wider variety of ordersthan the YOY, such as crustaceans (crayfish, shrimp) and mollusks (clams, snails). However, depending on prey availability, juveniles can eat smaller prey like ephemeropterans, dipterans, and trichopterans. Stomachs of juvenile sturgeon captured near Jackfish Island on the lower Nelson River contained mostly amphipods, trichopterans and chironomids.

As juveniles grow, they eat more large prey items like crayfish and mussels. Adult Lake Sturgeon are habitat generalists and are more flexible in their habitat selection and diet than juveniles or sub-adults.

For a more detailed explanation, please refer to section 1.1.5 of the KSNC Stewardship Plan (2016) .

Lake Sturgeon Movements

Lake Sturgeon movements can be studied using scientific methods (various tagging and tracking methods), although traditional knowledge holders within an area often understand the historical movement patterns of a species through observing their seasonal presence. Gilbert Beardy (York Factory First Nation) noted that, “Sturgeon prefer the fast deep water…sturgeon stay around the deep waters during the summer… when it’s warm they won’t go many places.”

In the lower Nelson River, adult Lake Sturgeon can travel distances of >50 km. Using the Nelson/Hayes shared estuary as a movement corridor, Nelson River individuals have been relocated in the Gods River (a tributary of the Hayes River) >340 km from where they were marked.

For a more detailed explanation, please refer to section 1.1.6 of the KSNC Stewardship Plan (2016).