LAKE STURGEON:

Most people have never seen a sturgeon and might find them intimidating. Not to worry, because they really are gentle according to staff and fishers who have handled them. They don't have sharp teeth or spines, their skin is tough but feels like sand-paper, and they don't seem inclined to push anyone around. Small ones under 3 kg do have sharp scutes (rows of bony plates) along their body, but these become flattened over time. The only problem with large ones might be getting between them and a solid object. Biologists find it easiest to just let any six-foot long specimens stretch whenever they want.
There are 26 species of sturgeon around the world, usually in coastal rivers and inland seas of Europe.

Canada has five species, with the Lake Sturgeon being the only permanent resident of freshwater lakes and rivers. The species ranges from the St. Lawrence River, north to James Bay, south to the Mississippi River, and west into Alberta. Saskatchewan has populations in the Saskatchewan River system (including a few lakes like Candle and Turtle historically) and in the lower Churchill River.
World-wide concern about habitat loss and over-fishing of sturgeon species lead to international restrictions under the Convention for International Trade in Endangered Species (CITES). Since the spring of 1998, exports of all sturgeon species or any parts require a permit that confirms they were legally taken. The concern is driven by the high value of caviar to rich consumers and the temptation for others to provide it. Sometimes European exporters and North American enforcement agencies argue heatedly over how to take samples for testing without spoiling whole containers, and whether 'legal' species hybridize with 'protected' species. The protection of species-at-risk sometimes meets big-money commerce head-first !

Fossils show that today's sturgeon look like they did more than 150-million years ago when dinosaurs roamed western Canada. Both the scutes and bony plates on their heads likely protected them against predators. Their front 'pectoral' fins are rather rigid, suggesting that they use them to plane in currents. The top of their tail fin is elongated like a shark. Interestingly, sturgeon intestines are shiny black for some reason.

Lake sturgeon commonly live from 40 to 60 years, but they can live for a century or longer. Ages are determined from cross-sections of pectoral fin-rays, which show annual light-and-dark bands (like tree rings). In Saskatchewan, the oldest sturgeon of known age was 64 years, but larger ones that would be older have been caught.

Somehow, lake sturgeon reach 20 kg or more by feeding on bottom organisms, such as clams and aquatic insects (immature mayflies, midges, and others). They detect prey with four barbels and electro-sensory pits on their snout. The mouth lies folded up, then extends up to 10 cm or more on larger fish. They use hard tooth-plates to crush food items.

In Saskatchewan, male sturgeon take 15 years to mature and females about 25 years. Our mature females spawn only once every four to seven years. This usually means that fewer than a hundred females spawn each year in any population. Females were historically the most sought-after fish since they are generally longer and heavier.

Since their replacement rate is low, sturgeon can only handle mortality of 5 to 10% each year. Even low 'natural mortality' due to injury or disease doesn't allow much fishing. Present-day populations typically number only a few thousand sturgeon. Sustainable harvests from 2,000 are only 100 to 200 each year. If the population has declined, harvests must be even lower for recovery.

Since 1999, any sturgeon that anglers catch incidentally in Saskatchewan must be returned to the water immediately. Similar restrictions are also in effect in Manitoba and Alberta.

Biologists are also concerned about loss of habitat, since it affects populations permanently. Spawning sites are often riffles or rapids, preferably water at least ½ m deep with moderate flows over a mix of rocks and gravel. Sites can be lost (by flooding or bypasses) or made unsuitable (by low flows during spawning). Barriers to spawning migrations may be less obvious, but just as destructive.

Action has begun on sturgeon habitat protection in Saskatchewan. This can be as simple as releasing water from control structures so spawning can occur and eggs and newly hatched 'fry' do not dry out. Or decisions can be more difficult, such as for hydro-electric dams, which are usually built near rapids and change flows substantially.

An assessment of lake sturgeon for the federal species-at-risk process is underway. If they are found to be endangered or threatened, a recovery plan will be required for sturgeon populations in western Canada.