Characteristics of a Lake Sturgeon Spawning Population Sampled a Half Century Apart

A lake sturgeon spawning assessment study conducted in the late 1940s below a dam on the Ottawa River, Canada was repeated over a 3-year period in 2001-2004. The objectives of the survey were to determine whether lake sturgeon, a long-lived species, continue to congregate at this location during the spawning period and to assess changes in the characteristics of the spawning population since 1949. Eighty-three lake sturgeon were caught, including 10 recaptures, over the 3-year survey with the majority of sturgeon sampled in 2003. The Schnabel population estimate for the 2003 spawning stock was 202 (93-378; 95% C.I.). Mean size of lake sturgeon sampled in the current survey (118.0 ± 12.8 S.D.) was greater than in the historical survey (101.7 ± 11.5 S.D.). However, lake sturgeon < 110 cm TL comprised only 31.1% of the sturgeon sampled in this survey whereas they comprised the majority of the catch in 1949 (69.9%), suggesting the population is experiencing a recruitment problem. Weight-length relationships of lake sturgeon did not vary between studies. Growth differed between studies which may be a function of aging error.