Reproductive strategy, spawning induction, spawning temperatures and early life history of captive sicklefin chub Macrhybopsis meeki-Data

Macrhybopsis reproduction and propagule traits were studied in the laboratory using two temperature regimes and three hormone treatments and which methods produced the most spawns. Only sicklefin chub (M. meeki) spawned successfully although sturgeon chub (M. gelida) released unfertilized eggs. All temperature and hormone treatments produced M. meeki spawns, but two treatments had similar success rates at 44 and 43%, consisting of a constant daily temperature with no hormone added, or daily temperature fluctuations with hormone added to the water. Spawns consisted of multiple successful demersal circular swimming spawning embraces interspersed with circular swims without embraces. The most spawns observed for one female was four and on average, 327 eggs were collected after each spawn. The water-hardened eggs were semibuoyant and nonadhesive, the first confirmation of this type of reproductive guild in the Missouri River Macrhybopsis sp. From spawn, larvae swam vertically until 123 accumulated thermal units (ATU) and 167 ATU for consumption of first food. Using average water velocity and laboratory development time, the predicted drift distance for eggs and larvae could be 468 to 592 km in the Lower Missouri River. Results from this study determined the reproductive biology and early life history of Macrhybopsis spp. and provided insight into their population dynamics in the Missouri River.