Lake Sturgeon
(Acipenser fulvescens)
Status: Endangered: Great Lakes - Upper St. Lawrence Populations, Threatened: Saskatchewan - Nelson River Populations, Special Concern: Southern Hudson Bay - James Bay Populations (ESA 2009, COSEWIC 2017)
Species Identification:
Lake Sturgeon are the largest freshwater fish in Canada. They can weigh up to 180 kg and reach lengths of over 2 m long. They are dark to light brown or grey in colour, and covered in large bony plates. These bony plates are harder to see the more the fish ages. They have a long snout and four organs that look like whiskers near their mouth. Unlike most fish, Lake Sturgeon are made up of cartilage instead of bones, and they can live for more than 100 years.
Diet:
The Lake Sturgeon eats primarily insect larvae, crayfish, molluscs, small fish, and sometimes plants. They will eat increasingly larger and more diverse species as they continue to grow, and their diet is mainly based on their size and habitat.
Habitat and Range:
Lake Sturgeon can be found only in North America. They can be found in freshwater habitats from Alberta east to Quebec, and Hudson Bay south to Alabama. The largest populations of Lake Sturgeon in Canada occur in Hudson Bay and the Great Lakes systems. They can be found in lakes and rivers in and around The Land Between such as Lake Nippising, Lake Simcoe, the Ottawa River, and the St. Lawrence river as well as its drainage rivers.
Lake Sturgeon can be found in a variety of lake and large river ecosystems. Their population structure and biology vary based on their type of habitat. Larger, deeper bodies of water with more food sources allow for larger Lake Sturgeon populations and larger fish themselves. For spawning and the first few stages of their lives, Lake Sturgeon needs fast or slow moving rivers with proper substrate. When they grow larger, Lake Sturgeon prefer the deeper waters of lakes and large rivers.
Biology and Behaviour:
Males arrive at spawning grounds upriver in the spring first and wait for the females to arrive. Preferred water temperatures for spawning are from 8-21.5°C. In fact, First Nations used to use the emergence of rose buds or poplar leaves in order to determine when Lake Sturgeon were spawning. Females will arrive anywhere within this spawning period, lay eggs and leave, whereas males will stay to mate with multiple females for the entire duration. The female will lay her eggs and soon after one or more males will arrive to fertilize them. The eggs soon develop a sticky exterior in order to stick to the substrate until the larvae can emerge. 5-20 days later, larvae will hatch and hide in the substrate until all of the yolk sack is consumed for food. The larvae must then emerge to find further food in the substrate by drifting downstream.
The larvae then grow into a stage known as age-0, where they resemble small fish and can be found in slow moving water less than 5 m deep with a sandy bottom. At this stage they will feed along the bottom of the river on benthic species like small aquatic larvae. They will head to slightly deeper water in the fall to overwinter. The habits of juveniles are not very well known, but it is expected that they will move to larger and deeper bodies of water, feeding on aquatic insects and small fish as they grow larger. Adults prefer deep lakes or rivers and will begin to also feed on larger species. While adult Lake Sturgeon generally do not have very many predators due to their size, eggs and larvae are often eaten by small fish and crustacean species.
Conservation and recovery strategies:
In areas where Lake Sturgeon are Endangered or Threatened they and their habitat are automatically protected. Special Concern populations are not protected directly, but may benefit from other species protections. Ontario, along with many other provinces, has created a recovery program for this species. This strategy aims to protect and increase Lake Sturgeon populations, maintain and enhance or restore known habitat, restore populations where they have been Extirpated, develop management strategies, increase public awareness, and fill in knowledge gaps with more research.
Government of Ontario. 2014. Lake sturgeon (Species at Risk). Retrieved from: https://www.ontario.ca/page/lake-sturgeon-species-risk
COSEWIC. 2017. COSEWIC assessment and status report on the Lake Sturgeon Acipenser fulvescens, Western Hudson Bay populations, Saskatchewan-Nelson River populations, Southern Hudson BayJames Bay populations and Great Lakes-Upper St. Lawrence populations in Canada. Committee on the Status of Endangered Wildlife in Canada. Ottawa. xxx + 153 pp. (http://www.registrelepsararegistry.gc.ca/default.asp?lang=en&n=24F7211B-1).
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