Genomic evidence for fisheries-induced evolution in Eastern Baltic cod

Area of Science:

• Marine Biology
• Evolutionary Genetics
• Fisheries Science

Background:

• Overfishing exerts significant evolutionary pressure on marine populations.
• Selective fishing practices can lead to rapid phenotypic changes.
• The genetic underpinnings of these trait changes are often unclear.

Purpose of the Study:

• To investigate growth trends in Eastern Baltic cod over 25 years of heavy fishing.
• To identify potential genetic changes associated with fisheries-driven trait alterations.
• To explore the genomic basis of growth impairment in an overexploited fish stock.

Main Methods:

• Analysis of a 25-year time series data for Eastern Baltic cod (Gadus morhua) growth.
• Genome-wide association study to identify genetic loci linked to growth performance.
• Examination of allele frequency changes and genetic differentiation signals.

Main Results:

• A significant 48% decrease in asymptotic body length was observed from 1996 to 2019.
• Genome-wide analysis identified outlier loci and candidate genes associated with reduced growth.
• These loci exhibited signals of directional selection and genetic differentiation.

Conclusions:

• Fisheries-driven overfishing has a discernible genomic basis for growth impairment in cod.
• The findings highlight the adaptive potential and evolutionary consequences for marine populations under fishing pressure.
• Implications for conservation policy and sustainable fisheries management are underscored.