Tracing the geographic origin of Atlantic cod products using stable isotope analysis

Area of Science:

• Marine Biology
• Fisheries Science
• Analytical Chemistry

Background:

• Growing demand for seafood necessitates robust traceability systems.
• Globalized supply chains complicate verification of marine product origins.
• Atlantic cod (Gadus morhua) is a commercially vital species in the Northeast Atlantic, with regional fisheries facing varying exploitation risks.

Purpose of the Study:

• To assess the efficacy of stable isotope ratios (carbon, nitrogen, sulfur) for retrospectively identifying the catch region of Atlantic cod.
• To develop and test assignment methods for classifying cod by origin using isotopic data.

Main Methods:

• Muscle tissue from 377 Atlantic cod across 10 Northeast Atlantic regions was analyzed for stable isotope composition (δ¹³C, δ¹⁵N, δ³⁴S).
• Three distinct assignment algorithms were employed to determine the most probable region of origin.
• The developed assignment method was validated using independent samples of known origin.

Main Results:

• Average assignment accuracy for individual cod to their true origin ranged from 70% to 79%.
• High accuracy (over 90%) was achieved for specific, well-defined regions.
• Overall assignment accuracy across the entire geographic range, using independent data, averaged approximately 25%.

Conclusions:

• Stable isotope analysis is a viable tool for verifying Atlantic cod origin, though not all regions are isotopically distinguishable.
• Integrating stable isotope techniques with genetic methods can enhance traceability accuracy beyond individual approaches.
• Accurate estimation of assignment potential requires validation with independently collected datasets.