Do native brown trout and non-native brook trout interact reproductively?

Area of Science:

• Ecology
• Ichthyology
• Conservation Biology

Background:

• Reproductive interactions between native and non-native fish species are understudied compared to predation or competition.
• Understanding these interactions is crucial for effective conservation and management of native aquatic ecosystems.

Purpose of the Study:

• To investigate the reproductive interactions between non-native brook trout (Salvelinus fontinalis) and native brown trout (Salmo trutta).
• To assess the potential impact of these interactions on the reproductive success of both species in a Pyrenees Mountain stream.

Main Methods:

• Field observation of spawning behavior and habitat use.
• Spatial and temporal analysis of redd (nest) locations.
• Identification of hybrids through observation and potentially genetic analysis.

Main Results:

• Significant spatial and temporal overlap was found between brook trout and brown trout spawning.
• Mixed spawning groups and subordinate interspecific males were observed.
• Natural hybridization, resulting in tiger trout, was documented.

Conclusions:

• Reproductive interactions between non-native brook trout and native brown trout occur frequently.
• These interactions, particularly hybridization, pose a potential threat to the reproductive success of native brown trout.
• Non-native species can negatively impact native species through subtle reproductive interference and hybridization.