eDNA based bycatch assessment in pelagic fish catches

Area of Science:

• Marine biology
• Fisheries science
• Environmental DNA (eDNA) analysis

Background:

• Pelagic fish like herring, sardines, and mackerel are vital global food sources.
• Sustainable fisheries management relies on accurate bycatch estimation methods.
• Current bycatch assessment methods can be imprecise or costly.

Purpose of the Study:

• To experimentally validate the use of eDNA for quantitative bycatch assessment.
• To investigate the eDNA method's efficacy in Baltic Sea sprat fisheries with herring bycatch.
• To assess the full eDNA pipeline from sampling to species weight fraction estimation.

Main Methods:

• Sampling of production water from fishing vessels and processing factories.
• Controlled mixture experiments to correlate eDNA signals with known herring biomass.
• Quantitative PCR (qPCR) and metabarcoding for eDNA signal analysis.
• Comparison of eDNA-based estimates with visual reporting data.

Main Results:

• A strong, seasonally consistent linear relationship was observed between eDNA signal and herring weight fractions.
• The relationship's strength varied depending on the molecular method (qPCR or metabarcoding).
• eDNA-based estimates showed higher precision compared to visual reporting across four analyzed sprat landings.
• Variability in herring bycatch biomass estimates was noted between different molecular methods.

Conclusions:

• eDNA-based bycatch assessment is a promising tool for improving accuracy and cost-effectiveness in pelagic fisheries.
• This method has the potential to enhance the sustainability of marine resource management.
• Further refinement of molecular methods can optimize eDNA-based bycatch assessment.