Relationships between Pacific salmon and aquatic and terrestrial ecosystems: implications for ecosystem-based...

Area of Science:

• Ecology
• Fisheries Science
• Conservation Biology

Background:

• Pacific salmon are crucial for temperate terrestrial and freshwater ecosystems.
• They facilitate nutrient dispersal and alter stream beds through spawning activities.
• Salmon also underpin significant fisheries, especially on North America's west coast.

Purpose of the Study:

• To synthesize relationships between Pacific salmon densities and ecosystem responses.
• To summarize the direction, shape, and magnitude of these ecological relationships.
• To identify potential ecosystem-based management indicators and benchmarks.

Main Methods:

• Conducted a comprehensive synthesis of 31 studies.
• Analyzed 172 distinct relationships between salmon density/abundance and ecological variables.
• Examined responses including species abundance, diversity, nutrient levels, and individual growth.

Main Results:

• Marine-derived isotopes showed the most frequent relationship with salmon density (40%).
• Few studies (5%) quantified ecosystem-level responses.
• Many relationships (46%) were non-asymptotic, indicating a lack of saturation, while 41% showed no significant relationship.

Conclusions:

• Salmon density effects on ecosystems are diverse and often non-saturating.
• Bear food consumption and freshwater fish abundance showed saturation.
• Key relationships, like bear food consumption, can inform ecosystem-based fisheries management indicators.