Intraspecific pheromone discrimination and substrate marking by atlantic salmon parr

Area of Science:

• Ichthyology
• Animal Behavior
• Chemical Ecology

Background:

• Atlantic salmon (Salmo salar L.) exhibit complex social behaviors.
• Understanding intraspecific communication is crucial for salmonid population dynamics.

Purpose of the Study:

• To investigate olfactory attraction and strain discrimination in Atlantic salmon parr.
• To identify the source and mode of transmission of intraspecific chemical cues.

Main Methods:

• Behavioral assays measuring attraction and preference to conspecific odors.
• Analysis of various tissue and fluid extracts for attractant compounds.
• Experiments using gravel treated with fish-associated materials.

Main Results:

• Salmon parr showed attraction to both familiar and unfamiliar conspecific odors.
• A significant preference was observed for odors from their own strain over unfamiliar ones.
• Attractants were found in intestinal contents and bile, suggesting hepatic origin and fecal excretion.
• Gravel extracts induced strain-related preferences, indicating substrate marking via fecal deposition.
• No strain discrimination was observed with skin mucus or blood plasma extracts.

Conclusions:

• Pheromones mediate strain recognition and preference in juvenile Atlantic salmon.
• The liver and intestinal tract are likely sources of these discriminative pheromones.
• Substrate marking, possibly through fecal material, plays a role in spatial organization and homing behaviors.