Fish Movements in Toronto Harbour Associated with Upwelling Events

Fish habitat selection and movements are influenced by a suite of environmental variables. Water temperature is one of the most studied due to the intrinsic effect of this variable on the biological processes of organisms. Littoral fish are particularly influenced by fluctuations in water temperatures, mainly during the summer where this process is more common. The Toronto Harbour exhibits such temperature fluctuations, or upwellings, with changes of around 10-16^oC in relatively short time periods. This type of event can occur several times during the summer, and with different intensities, such that the effects can be spread to relatively protected areas of the inner harbour. Fish that inhabit these areas of the lake have to cope with the rapid changes in temperature; therefore their movements should be influenced by the irregular environmental process. This study explores fish movements in the Toronto Harbour during three upwelling events of 2012. Fish were tagged with acoustic transmitters, released and tracked with an array of receivers that covered the area of the harbour. Water temperatures were recorded throughout the duration of the study. This research will help understand the habitat selection for resident and non-resident fish during environmental disturbances such as the upwelling events