A future for seafood point-of-origin testing using DNA and stable isotope signatures

Demand for seafood products is increasing worldwide, contributing to ever more complex supply chains and posing challenges to trace their origin and guarantee legal, well-managed, sustainable sources from confirmed locations. While DNA-based methods have proven to be reliable in verifying seafood authenticity at the species level, the verification of geographic origin remains inherently more complex. Both genetic and stable isotope analyses have been employed for determining point-of-origin with varying degrees of success, highlighting that their application can be effective when the right tool is selected for a given application. Developing an a priori prediction of their discrimination power for different applications can help avoid the financial cost of developing inappropriate reference datasets. Here, we reviewed the application of both techniques to seafood point-of-origin for 63 commercial finfish species certified by the Marine Stewardship Council, and showed that, even for those species where baseline data exist, real applications are scarce. To fill these gaps, we synthesised current knowledge on biological and biogeochemical mechanisms that underpin spatial variations in genetic and isotopic signatures. We describe which species’ biological and distribution traits are most helpful in predicting effectiveness of each tool. Building on this, we applied a mechanistic approach to predicting the potential for successful validation of origin to three case study fisheries, using combined genetic and isotopic methodologies to distinguish individuals from certified versus non-certified regions. Beyond ecolabelling applications, the framework we describe could be reproduced by governments and industries to select the most cost-effective techniques

A future for seafood point-of-origin testing using DNA and stable isotope signatures

Demand for seafood products is increasing worldwide, contributing to ever more complex supply chains and posing challenges to trace their origin and guarantee legal, well-managed, sustainable sources from confirmed locations. While DNA-based methods have proven to be reliable in verifying seafood authenticity at the species level, the verification of geographic origin remains inherently more complex. Both genetic and stable isotope analyses have been employed for determining point-of-origin with varying degrees of success, highlighting that their application can be effective when the right tool is selected for a given application. Developing an a priori prediction of their discrimination power for different applications can help avoid the financial cost of developing inappropriate reference datasets. Here, we reviewed the application of both techniques to seafood point-of-origin for 63 commercial finfish species certified by the Marine Stewardship Council, and showed that, even for those species where baseline data exist, real applications are scarce. To fill these gaps, we synthesised current knowledge on biological and biogeochemical mechanisms that underpin spatial variations in genetic and isotopic signatures. We describe which species’ biological and distribution traits are most helpful in predicting effectiveness of each tool. Building on this, we applied a mechanistic approach to predicting the potential for successful validation of origin to three case study fisheries, using combined genetic and isotopic methodologies to distinguish individuals from certified versus non-certified regions. Beyond ecolabelling applications, the framework we describe could be reproduced by governments and industries to select the most cost-effective techniques. Graphic abstract: [Figure not available: see fulltext.

Moult location and diet of auks in the North Sea inferred from coupled light-based and isotope-based geolocation

Many pelagic seabirds moult their feathers while at sea, which is an energetically costly behaviour. Mortality rates during moult can be high, so spatial and trophic ecology during this critical period is important for understanding demographic patterns. Unfortunately, individual foraging behaviours specifically linked to at-sea moulting are commonly unclear. This paper combines 2 different approaches to geolocation: data from bird-borne geolocation loggers and stable-isotope assignment using carbon and nitrogen isotope maps (isoscapes). Coupling 2 geolocation processes allows some uncertainties associated with isotope-based assignment to be constrained. We applied this approach to quantify species-specific foraging locations and individual trophic variability during feather regrowth in 3 sympatric auk populations breeding on the Isle of May, Scotland (common guillemot Uria aalge, razorbill Alca torda and Atlantic puffin Fratercula arctica). Inferred foraging areas during moult differed between species and feather types. Guillemots likely underwent moult within the southern North Sea, razorbills along the east coast of England and into the southern North Sea and puffins off the east coast of Scotland. Estimates of individual trophic position varied considerably within feather types (up to 1 trophic level difference between individuals), among feather types grown during different time periods and across the 3 species, with guillemots consistently foraging at higher trophic positions than razorbills and puffins. Used in combination, these methods better constrain foraging areas during moulting, and provide a technique to explore individual differences and flexibility in foraging strategy, which is valuable information for both seabird conservation and marine spatial planning

An environmental (pre)history of European fishing: past and future archaeological contributions to sustainable fisheries.

This paper explores the past and potential contribution of archaeology to marine historical ecology. The primary focus is European fishing of marine and diadromous taxa, with global comparisons highlighting the wider applicability of archaeological approaches. The review illustrates how study of excavated fish bones, otoliths and shells can inform our understanding of: (a) changes in biogeography, including the previous distribution of lost species; (b) long-term fluctuations in the aquatic environment, including climate change; (c) the intensity of exploitation and other anthropogenic effects; (d) trade, commodification and globalisation. These issues are also relevant to inform fisheries conservation and management targets. Equally important, the long (pre)history of European fishing raises awareness of our ecological heritage debt, owed for centuries of wealth, sustenance and well-being, and for which we share collective responsibility. This debt represents both a loss and a reason for optimism, insofar as it is a reservoir of potential to be filled by careful stewardship of our rivers, lakes, seas and oceans

Effects of body size, sex, parental care and moult strategies on auk diving behaviour outside the breeding season

Information on seabird foraging behaviour outside the breeding season is currently limited. This knowledge gap is critical as this period is energetically demanding due to post‐fledging parental care, feather moult and changing environmental conditions. Based on species’ body size, post‐fledging parental strategy and primary moult schedule we tested predictions for key aspects of foraging behaviour (Maximum Dive Depth (MDD), Daily Time Submerged (DTS) and Diurnal Dive Activity (DDA)) using dive depth data collected from three seabird species (common guillemot Uria aalge, razorbill Alca torda and Atlantic puffin Fratercula arctica) from the end of the breeding season (July) to mid‐winter (January). We found partial support for predictions associated with body size; guillemots had greater MDD than razorbills but MDD did not differ between razorbills and puffins, despite the former being 35% heavier. In accordance with sexual monomorphism in all three species, MDD did not differ overall between the sexes. However, in guillemots and razorbills there were sex‐specific differences, such that male guillemots made deeper dives than females, and males of both species had higher DTS. In contrast, there were no marked sex differences in dive behaviour of puffins in July and August in accordance with their lack of post‐fledging parental care and variable moult schedule. We found support for the prediction that diving effort would be greater in mid‐winter compared to the period after the breeding season. Despite reduced daylight in mid‐winter, this increase in DTS occurred predominantly during the day and only guillemots appeared to dive nocturnally to any great extent. In comparison to diving behaviour of these species recorded during the breeding season, MDD was shallower and DTS was greater during the non‐breeding period. Such differences in diving behaviour during the post‐breeding period are relevant when identifying potential energetic bottlenecks, known to be key drivers of seabird population dynamics

The retrospective relocation of free-living marine organisms using stable isotopes

Isoscapes are spatially explicit models describing isotopic variability due to spatial differences in physical, chemical and biological processes across natural environments. Marine isoscapes are being increasingly developed to address a range of ecological questions, from better understanding space use and foraging behaviours to determining individual trophic feeding positions and assigning animals or animal products to their origin. However, many marine isoscapes lack suitable data coverage and resolution or explicit measures of variance, necessary for assignment. This research aims to advance isoscape prediction methodologies and develop isoscape assignment techniques to benefit marine conservation and management.I have demonstrated two different methods of isoscape prediction. The first, ordinary kriging of in situ δ13C and δ15N measurements of lion’s mane jellyfish (Cyanea capillata) across the North Sea, producing highly accurate isoscapes. The second, a Bayesian hierarchical modelling approach incorporating multiple species of in situ jellyfish samples and additional environmental data to produce highly precise δ13C, δ15N and δ34S UK shelf sea isoscapes. Both techniques provided greater than 80% assignment accuracy to areas representing 40% of each isoscape. North Sea assignments were comparable to light based data loggers and UK shelf sea assignment accuracy was approximately 80% when assigning to ICES subareas. I also demonstrated marine isoscape use in seabird foraging behaviour research, by refining over winter feeding positions during the vulnerable moult period of UK breeding guillemots (Uria aalge), razorbills (Alca torda) and Atlantic puffins (Fratercula arctica). The three sympatric species frequented slightly different areas and fed over different trophic positions, with high individual variability. Foraging responses also differed between winters with contrasting environmental conditions, with razorbill and puffin populations displaying different adaptation strategies.This study addresses current limitations of sample collection constraints in marine isoscape predictions and highlights the potential of animal assignments to isoscapes as a useful tool to aid conservation, fisheries management and traceability

The retrospective geolocation of free-living marine organisms using stable isotapes

Isoscapes are spatially explicit models describing isotopic variability due to spatial differences in physical, chemical and biological processes across natural environments. Marine isoscapes are being increasingly developed to address a range of ecological questions, from better understanding space use and foraging behaviours to determining individual trophic feeding positions and assigning animals or animal products to their origin. However, many marine isoscapes lack suitable data coverage and resolution or explicit measures of variance, necessary for assignment. This research aims to advance isoscape prediction methodologies and develop isoscape assignment techniques to benefit marine conservation and management. I have demonstrated two different methods of isoscape prediction. The first, ordinary kriging of in situ 13C and 15N measurements of lion’s mane jellyfish (Cyanea capillata) across the North Sea, producing highly accurate isoscapes. The second, a Bayesian hierarchical modelling approach incorporating multiple species of in situ jellyfish samples and additional environmental data to produce highly precise 13C, 15N and 34S UK shelf sea isoscapes. Both techniques provided greater than 80% assignment accuracy to areas representing 40% of each isoscape. North Sea assignments were comparable to light based data loggers and UK shelf sea assignment accuracy was approximately 80% when assigning to ICES subareas. I also demonstrated marine isoscape use in seabird foraging behaviour research, by refining over winter feeding positions during the vulnerable moult period of UK breeding guillemots (Uria aalge), razorbills (Alca torda) and Atlantic puffins (Fratercula arctica). The three sympatric species frequented slightly different areas and fed over different trophic positions, with high individual variability. Foraging responses also differed between winters with contrasting environmental conditions, with razorbill and puffin populations displaying different adaptation strategies. This study addresses current limitations of sample collection constraints in marine isoscape predictions and highlights the potential of animal assignments to isoscapes as a useful tool to aid conservation, fisheries management and traceability

Data from: Stable isotope-based location in a shelf sea setting: accuracy and precision are comparable to light-based location methods

Retrospective determination of location for marine animals would facilitate investigations of migration, connectivity and food provenance. Predictable spatial variations in carbon and nitrogen isotopes in primary production across shelf seas provide a basis for stable isotope-based location. Here, we assess the accuracy and precision that can be obtained through dietary-isotope-based location methods. We build isoscapes from jellyfish tissues and use these to assign scallops of fixed and known individual location, and herring with well-understood population-level distributions in the North Sea. Accuracy and precision for retrospective isotope-based location in the North Sea were of a similar order to light-based location devices, with 75% of individual scallops assigned correctly to areas representing c. 30% of the North Sea, with a mean linear error on the order of 102 km. Applying assignment methods to an alternative migratory species (herring) resulted in ecologically realistic assignments consistent with fisheries survey data. Location methods based on dietary isotopes such as carbon and nitrogen recover the spatial origin of nutrients assimilated into tissues, and this may not correspond directly to the physical location if either the test animal or its prey is highly migratory. Stable isotope-based location can be applied to any marine-feeding organism or derived food product, but the ecological meaning of any assigned area will be more difficult to interpret for large, high trophic level, migratory animals with relatively slow isotopic assimilation rates.,TableS1 Stable isotope results C. capillataLatitude, Longitude, Weight, Bell diameter, stable isotope (d15N, d13C) and CN ratio for individual C. capillata sampled across the North Sea in Sept 2015TableS1.txtTableS2 Stable isotope data from herring from the North SeaLocations of capture (lat, long) and stable isotope (d13C d15N) values for herring caught across the North Sea in Sept. 2011TableS2.txtJennings.2001Stable isotope data (lipid corrected d13C, d15N) from queen scallops published in Jennings &amp;amp; Warr 2003 and Barnes et al., 2009,</span

Seasonal carbon and nitrogen isoscapes in the Southern Ocean

We produced carbon and nitrogen isoscapes across the entire Southern Ocean (>40°S) using surface particulate organic matter isotope data, collected over the past 50 years. We used Integrated Nested Laplace Approximation -based approaches to predict mean annual isoscapes and four seasonal isoscapes using a suite of environmental data as predictor variables