Reconstructing History: Scale Analysis Reveals Long-Term Changes in Age-Related Growth of a Coregonid Fish

Area of Science:

• Ecology
• Ichthyology
• Environmental Science

Background:

• Long-term data on individual animal growth in natural populations are scarce.
• Understanding growth drivers requires integrating environmental factors and life-history trade-offs.

Purpose of the Study:

• To reconstruct age-specific growth histories of coregonid fish (Coregonus sp.) over 22 years.
• To evaluate the influence of lake phosphorus concentrations and spring temperatures on fish growth.
• To investigate age-specific responses to environmental changes and life-history strategies.

Main Methods:

• Scale analysis was used to reconstruct individual fish age and growth histories.
• Linear mixed-effects models were applied to analyze growth trends and environmental drivers.
• Coregonid fish from Lake Starnberg, Germany, were studied over a 22-year period.

Main Results:

• Coregonid growth remained stable or increased in younger fish (ages 1-2) but significantly declined in mature fish (age 3).
• Lake phosphorus concentrations decreased, indicating reduced nutrient availability.
• Temperature effects on growth varied by age class, despite no significant long-term temperature trend.

Conclusions:

• Mature fish growth decline aligns with life-history theory, suggesting a shift towards reproductive investment.
• Environmental changes interact with intrinsic life-history strategies, causing age-specific growth variations.
• This study provides rare empirical evidence of long-term growth dynamics in a natural fish population.