Seasonal movements of lake sturgeon in Lake of the Woods and the Rainy River, Ontario

Abstract

Lake sturgeon (Acipenser fulvescens) inhabiting the southern portion of Lake of the Woods and the Rainy River, a north-temperate watershed straddling the Canada – United States border, were studied to test hypotheses concerning seasonal movement patterns, including spawning migrations, and habitat use. We implanted radio transmitters into 26 fish and monitored seasonal movements during 3 consecutive years. Data indicated the existence of two discrete populations of sturgeon in this watershed, differentiated by seasonal habitat use, movement patterns and rates, and timing of spawning. The "lake" population, a designation suggested by a consistent preference for lentic winter habitat, appeared to spawn and initiate extensive spring and summer movements later than the "river" population, which consistently inhabited the river during the winter months. Overall, movement rates were significantly greater in the spring and summer months than at other times of the year and decreased with water temperature. General preferences exhibited by lake sturgeon for certain habitat types at different times of the year appeared to be linked to foraging behaviour. The results suggest that population differentiation may be prevalent for this species inhabiting large lake–river systems, given some diversity in habitat structure and spawning cues. In management efforts, this potential should be taken into consideration and reflected.

Movement of Lake Sturgeon, <em>Acipenser fulvescens</em>, in a Natural Reach of the Ottawa River

“…Homing or site fidelity by Lake Sturgeon has previously been described (Threader and Brousseau 1986;Fortin et al 1993;Rusak and Mosindy 1997;Auer 1999;Caswell et al 2004). This area of the river is characterized by a sandy, clay substrate, which should be productive for benthic invertebrates, the primary source of prey for sturgeon.…”

“…This is comparable to a 2 -6 m preference by Lake Sturgeon in the Groundhog River in northern Ontario (Seyler 1997) and depths < 2.5 m in the Mattagami River (McKinley et al 1998). Lake Sturgeon, however, were most frequently located in water depths > 6 m in Rainy Lake (Rusak and Mosindy 1997). Lake Sturgeon usually inhabit waters from 4 to 9 m (Houston 1987).…”

Reintroduction of Lake Sturgeon (Acipenser fulvescens) into the St. Regis River, NY: Post- Release Assessment of Habitat Use and Growth

“…comm.). Rusak and Mosindy (1997) observed segregation of lake and river populations based on the commencement of spawning migrations and winter habitat preferences in the absence of physical barriers in the Lake of the Woods.…”

“…Spawning migrations of over 100 km have been recorded (Scott and Crossman 1998). However, there is thought to be strong site fidelity with spawning fish returning to the same sites year after year, although the occasional fish may wander from lake to lake to spawn (Swanson et al 1991;Rusak and Mosindy 1997). In the Moose River, juveniles and adults appear to occupy the same areas and there is no evidence of juvenile dispersion (Seyler 1997a).…”

Lake Sturgeon, <em>Acipenser fulvescens</em>, Movements in Rainy Lake, Minnesota and Ontario

“…However, in the past decade, Lake Sturgeon movements have been studied at an increasing rate throughout much of the species' range (Rusak and Mosindy 1997;McKinley et al 1998;Auer 1999;Borkholder et al 2002;Knights et al 2002). Lake Sturgeon have been found to move large distances for purposes such as spawning (Threader and Brosseau 1986;Fortin et al 1993;Rusak and Mosindy 1997;Auer 1999) while maintaining smaller ranges in other systems (Bassett 1982*). Such movement patterns make Lake Sturgeon management difficult, particularly for multiple agencies dealing with border waters of substantial size.…”