Nutrient footprint versus EPA + DHA security in land-locked regions-more of local pond farmed, imported marine fish or fish oil capsules?

EPA + DHA intake in land-locked central Europe (CE) is barely fulfilled. Imported marine fish/farmed salmonids are likely the backbone of an ailing EPA + DHA security. Supplementing with captured marine fish oil capsules (~0.5 g up to 1.6 g CO2-eq. mg EPA + DHA-1) could be comparable in GHG emissions with fish consumption itself (~1 g to as low as 0.6 g CO2-eq. mg EPA + DHA-1). But synergistic benefits of EPA + DHA intake by consuming fish protein need consideration too. Taking semi-intensive pond carp and intensively farmed salmon as models, we analyzed footprint, eco-services, and resource use efficiency perspectives of achieving EPA + DHA security in a CE region. Despite a lower production footprint, pond-farmed fish greatly lag in EPA + DHA supply (carp 101-181 mg 100 g-1 < salmon 750-1300 mg 100 g-1). It doubles-to-quadruples footprint 'per mg' of EPA + DHA: nitrogen (carp 18.3 > salmon 8.7 mg N), phosphorus (carp 6.8 > salmon 1.6 mg P), and climate change (carp 1.84 > salmon 0.8 g CO2-eq.). With enhancements in pond carp (>300 mg EPA + DHA 100 g-1), these differences may cease to exist. Harnessing EPA + DHA bioaccumulation pathways active in ponds, finishing feeding strategies, and polyculture, the EPA + DHA content in pond fish may be increased. Ecosystem services with EPA + DHA mining from pond food web or high EPA + DHA output-to-input ratio (pond carp 1-200 > RAS salmon 0.75) make ponds an eco-efficient system. As fish consumption in CE must improve, pond-farmed fish would be needed to complement (but not substitute) salmonid/marine fish/oil capsules consumption. Achieving EPA + DHA security with minimum pressure on the environment or global resources.

Determination of trace element and fatty acid levels in tissues of mirror and scaly carp (Cyprinus carpio L., 1758) living in Keban Dam Reservoir (Elazig)

This study investigated the concentrations of some accumulated trace metals (iron, manganese, zinc and copper) and fatty acids in liver and muscle tissues of mirror and scaly carp varieties (Cyprinus carpio L., 1758) living in Keban Dam Reservoir (Elazig), which is the second-largest artificial lake in Turkey that hosts commercially valuable and preferred fish varieties for human consumption. The inductively coupled plasma mass spectrometry (ICP-MS) method was used to analyse the concentrations of trace elements. Fatty acid levels were measured in a gas chromatography mass spectrometry (GC-MS) device, using a flame ionization detector (FID). Considering the two fish varieties and tissues that were studied, the mean metal concentrations (μg g^-1 ) were found in the following ranges: Fe 12.32-49.97, Mn 0.12-0.62, Zn 10.45-86.59 and Cu 2.74-11.86. Although the lowest levels were detected in the muscle tissue for all the metals examined, the levels in the liver tissue were significantly higher. According to the results of the analyses on fatty acid concentrations, the mean total saturated fatty acid levels in the muscle tissue of the scaly carp and mirror carp varieties were found to be 31.07 and 31.43 (%), respectively, whereas these values for the liver tissue were consecutively 22.36 and 22.08 (%). Successively, the mean total levels of unsaturated fatty acids were determined as 68.93 and 68.40 (%) in the muscle tissue and 77.64 and 77.92 in the liver tissue. This study, with the finding that the trace (metallic) element accumulation rates were below the upper limits of the tolerable range, and the examined fish varieties were rich in fatty acids, shows that mirror carp and scaly carp living in Keban Dam Reservoir are highly nutritious for human diets.

Nutritional Characterisation of European Aquaculture Processing By-Products to Facilitate Strategic Utilisation

Sustainability analyses of aquaculture typically ignore the fate and value of processing by-products. The aim of this study was to characterise the nutritional content of the common processing by-products (heads, frames, trimmings, skin, and viscera) of five important finfish species farmed in Europe; Atlantic salmon (Salmo salar), European seabass (Dicentrarchus labrax), gilthead seabream (Sparus aurata), common carp (Cyprinus carpio), and turbot (Psetta maxima) to inform on best utilisation strategies. Our results indicate a substantially higher total flesh yield (64–77%) can be achieved if fully processed, compared to fillet only (30–56%). We found that heads, frames, trimmings and skin from Atlantic salmon, European seabass, gilthead seabream and turbot frames showed medium to high edible yields, medium to high lipid, and medium to high eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) content, indicating significant potential for direct use in human food. By-products which are unattractive for use in food directly but have low ash content and medium to high crude protein, lipid and EPA and DHA content, such as viscera, could be directed to animal feed. Skin showed interesting nutritional values, but has more potential in non-food applications, such as the fashion, cosmetic and pharmaceutical industries. The results indicate potential to increase the direct food, animal feed and non-food value of European aquaculture, without an increase in production volumes or the use of additional resources. The importance of changing consumer perceptions and addressing infrastructure and legislative barriers to maximise utilisation is emphasised.