(2024). Tracing the geographic origin of Atlantic cod products using stable isotope analysis. Rapid Communications in Mass Spectrometry. INPRESS. https://doi.org/10.1002/rcm.9861, https://archimer.ifremer.fr/doc/00901/101276/
Copy this text
Tracing the geographic origin of Atlantic cod products using stable isotope analysis
Rationale
Increasing demand for fish and seafood means that the traceability of marine products is becoming ever more important for consumers, producers and regulators. Highly complex and globalised supply networks create challenges for verifying a stated catch region. Atlantic cod is one of the most commercially important species in the northeast Atlantic. Several regional fisheries supply cod into the trade network, of which some are at greater risk of overexploitation than others. Tools allowing retrospective testing of spatial origin would significantly assist sustainable harvesting of fish, reducing incentives for illegal fishing and fraud.
Methods
Here, we investigate whether stable isotope ratios of carbon, nitrogen and sulphur can be used to retrospectively identify the catch region of Atlantic cod (Gadus morhua). We measured the isotopic composition of muscle tissue from 377 cod from 10 catch regions across the northeast Atlantic and then applied three different assignment methods to classify cod by region of most likely origin. The assignment method developed was subsequently tested using independently sourced, known-origin samples.
Results
Individual cod could be traced back to their true origin with an average assignment accuracy of 70–79% and over 90% accuracy for certain regions. Assignment success rates comparable to those using genetic techniques were achieved when assigning among restricted and pre-selected regions. However, assignment accuracy to the fishery region estimated from independent samples across the whole geographic range of cod averaged ~25% overall, highlighting the need for careful application of isotope-based approaches.
Conclusion
Stable isotope techniques can provide effective tools to test for origin in Atlantic cod, but not all catch regions are isotopically distinct. Stable isotopes could be combined with genetic techniques to result in higher assignment accuracy than could be achieved using either method independently. Assignment potential can be estimated from reference datasets, but estimates of realistic assignment accuracy require independently collected data.
Full Text
| File | Pages | Size | Access | |
|---|---|---|---|---|
Publisher's official version IN PRESS | 12 | 1 Mo | ||
Data S1. Supporting Information | - | 38 Ko | ||
Figure S1 Frequency distributions of δ13C, δ15N and δ34S values from Atlantic cod caught within each of the ten sampled regions. | 1 | 1 Mo | ||
Figure S2 Carbon, nitrogen and sulfur stable isotope values for each individual cod sampled, coloured by region of origin. The 90% data ellipses are also shown for each geographic region. | 1 | 1 Mo | ||
Figure S3 Assignment results using carbon, nitrogen and sulfur stable isotope data, showing the percentage of individuals from each known location assigned to all the possible regions over 1000.... | 1 | 327 Ko | ||
Figure S4 Assignment results using only carbon and nitrogen stable isotope data, showing the percentage of individuals from each known location assigned to all the possible regions over 1000.... | 1 | 56 Ko | ||
Figure S5 Linear discriminant analysis (LD1 and LD2) using the carbon, nitrogen and sulfur stable isotope compositions measured in cod muscle tissue from each of the sampled regions. | 1 | 3 Mo | ||
Figure S6 Locations of sampling stations within ICES sub area boundaries (grey lines), and assignment success rates in each region using random forest classification with a leave-one-out cross ... | 1 | 1 Mo | ||
Figure S7 Carbon and nitrogen stable isotope values measured in cod samples collected in this study (reference samples) compared with those collected from previous years and studies (test samples),... | - | 98 Ko | ||
Figure S8 Locations where independent cod samples were collected previously by Jennings and Cogan54 compared to the locations where samples were collected for the current study in 2018 in the ... | - | 98 Ko | ||
Data S2. Supporting Information | - | 5 Mo | ||
Data S3. Supporting Information | - | 13 Ko | ||
Table S1 Total number of individual Atlantic cod collected from each geographic region, the number of stations sampled per region, and the source from which samples were obtained. | - | 15 Ko | ||
Table S2 Comparison of the mean values and uncertainties (standard deviations) in the stable isotope measurements of two internal standards measured at both laboratories where samples were analysed. | - | 14 Ko | ||
Table S3 Means and standard deviations of carbon (lipid corrected), nitrogen and sulfur stable isotope ratios from Atlantic cod caught in each of the sampled geographic regions. | - | 14 Ko | ||
Table S4 Mean percentage of individuals assigned to the correct origin region over 1000 repeat simulations using three isotopes (δ13C, δ15N and δ34S) and two isotopes (δ13C and δ15N). | - | 15 Ko | ||
Table S5 Leave-one-out cross validation results using the multivariate normal probability method, showing the number of samples assigned to each of the geographic regions as well as the percentage ... | - | 15 Ko | ||
Table S6 Assignment results to each of the geographic regions using linear discriminant analysis, showing the mean percentage over 1000 repeat simulations. The correct assignments for each region ... | - | 16 Ko | ||
Table S7 Leave-one-out cross validation results using random forest classification, showing the number of samples assigned to each of the geographic regions as well as the percentage of correct... | - | 14 Ko |
How to cite