Brook trout are an important fishery across eastern North American. Brook trout reproduction in lakes relies on spawning in tributaries or along lake shorelines with upwelling groundwater. Sizeable tributaries are often limited in small lakes, typical of the Adirondack mountains of New York and other regions. In these cases, brook trout rely solely on areas of discharging groundwater along the shoreline. While groundwater is usually well buffered relative to lake ecosystems, we have documented acidic groundwater discharging into brook trout redds in a small lake in the western Adirondacks with poor wild brook trout reproduction (Warren et al. 2005). How prevalent is this phenomenon? What are some of the watershed conditions that may promote acid groundwater? How can it be mitigated?

We are also interested in how changing climate conditions influence fish in these headwater ecosystems. Long-term assessments of spawning in one of our study lakes demonstrated reduced spawning activity and delayed fall spawning in years with hot summers (Warren et al. 2012). We are currently exploring this phenomon across multiple lakes with varying morphology and thermal refuge.

Brook trout are not restricted to their native range. While efforts in the eastern US focus on brook trout protection, efforts in the western US, where brook trout are invasive often focus on brook trout removal. Brook trout were historically stocked into numerous mountain lakes across the western US to provide fishing in remote wilderness areas (and they still are in many system). The ability for brook trout to effectively reproduce using discharging groundwater along lakes shorelines has lead to sustained brook trout populations in many lakes that would otherwise be fishless. The impacts of brook trout on these previously fishless systems can be striking as they exert top-down controls on lake food webs. The effects of brook trout in Oregon lakes remains surprisingly understudied though. I am beginning to explore this issue in Cascade Mountain Lakes in central Oregon.

Collaborators

• Daniel Josephon
• Clifford Kraft
• Jesse Lepak
• Jason Robinson
• Stephen Sebestyen
• Daniel Sheldon
• Peter Stevens