Asian carp spawning success: Predictions from a 3-D hydrodynamic model for a Laurentian Great Lake tributary

Abstract

Asian carps are threatening to establish in the Great Lakes basin and the examination of factors leading to spawning success is vital for preventive efforts. Hydrodynamic modelling can determine if successful hatching of carp eggs can occur in a tributary, by predicting egg movement during a spawning event to see if hatching can occur before eggs settle. A 3-D hydrodynamic model, coupled with a Lagrangian particle tracker, was used to assess hatching rates of three Asian carp species (bighead, grass, and silver carps) in different temperature and flow scenarios in the east Don River, a potential spawning tributary to Lake Ontario. In-river hatching rates were highest in scenarios with warmer summer water temperatures (23–25 °C) and flow magnitudes of 15–35 m3/s, which occur at least once every year. Using a 3-D hydrodynamic model allowed the inclusion of low-velocity zones where eggs become trapped in lower flow scenarios, thereby reducing modelled hatching success. In-river hatching rates were significantly reduced when the spawning location was moved close to the mouth of the river, with no modelled hatching if spawning occurred in the lower 8 km of the Don River, indicating that preventing Asian carp movement upstream would viably reduce the chances of successfully spawning occurring in this tributary. The magnitude of reduction in spawning success caused by limiting Asian carp passage upstream can guide preventative strategies and the method of using a 3-D hydrodynamic model as a predictive tool could be applied in similar tributaries across the Great Lakes basin.