Status of Fishery Discards and By-Products in Greece and Potential Valorization Scenarios towards a National Exploitation Master Plan.

The valorization of aquaculture/fishery processing by-products, as well as unavoidable/unwanted catches and discards in Greece, is currently an underutilized activity despite the fact that there are several best practices in Northern Europe and overseas. One of the main challenges is to determine whether the available quantities for processing are sufficient to warrant the valorization of discards and fish side streams. This is the first attempt to systematically record and analyze the available quantities of fish by-products and discards in Greece spatially and temporally in an effort to create a national exploitation Master Plan for the valorization of this unavoidable and unwanted biomass. A thorough survey conducted within the VIOAXIOPIO project unveiled a substantial biomass of around 19,000 tonnes annually that could be harnessed for valorization. Furthermore, the production of various High-Added-Value Biomolecules (HAVBs) was investigated and experimental trials were conducted to assess the potential yields, with the collected data used to formulate four valorization scenarios.

Metals in sardine and anchovy from Greek coastal areas: Public health risk and nutritional benefits assessment.

Concentrations of 26 metals and elements were measured in sardine (Sardina pilchardus) and anchovy (Engraulis encrasicolus) sampled from 6 Greek coastal areas in order to assess public health risks and benefits. Nutritional benefits seem to outweigh the potential risks arising from fish metal content, since various parameters (Safety Standards, Estimated Daily Intake, Maximum Safe Consumption, Hazard Quotient, Metal Pollution Index, As Carcinogenic Risk, Mercury toxicity - Selenium benefits, Nutrient Reference Values) indicated mostly safe consumption of the studied species. Weekly consumption of 480.76 g of sardine and anchovy poses minor risks (due to increased levels of essential metals like Fe and Zn in some cases) but great benefits regarding intake of essential elements like Mg, Fe, Cu, Zn, Mo, Ca, P, Se. The traces of inorganic As detected were well below all safety limits. Hg toxicity symptoms are not likely to appear and Se benefits are not likely to be compromised.

Metals and elements in sardine and anchovy: Species specific differences and correlations with proximate composition and size.

Species - specific differences in the levels of 26 metals and elements in sardine and anchovy are investigated and the factors of proximate composition (proteins, lipids, ash) and body size (length, weight) that may affect the metal and elemental concentrations in fish are explored. Statistical analysis revealed that levels of metals and elements in fish seem to strongly depend on species. Significantly higher levels of most of the metals and elements studied have been observed in anchovy compared to sardine at each of six different sites. The observed species-specific differences in metal content could be attributed to different proximate composition and size among other factors. The significant (positive or negative) correlations found between lipids, proteins, ash, weight, length and metals or elements, suggest that higher levels of most of the metals and elements studied can be associated with lower lipid content, greater protein and ash content and smaller size.

Interannual Changes in Biomass Affect the Spatial Aggregations of Anchovy and Sardine as Evidenced by Geostatistical and Spatial Indicators.

Geostatistical techniques were applied and a series of spatial indicators were calculated (occupation, aggregation, location, dispersion, spatial autocorrelation and overlap) to characterize the spatial distributions of European anchovy and sardine during summer. Two ecosystems were compared for this purpose, both located in the Mediterranean Sea: the Strait of Sicily (upwelling area) and the North Aegean Sea (continental shelf area, influenced by freshwater). Although the biomass of anchovy and sardine presented high interannual variability in both areas, the location of the centres of gravity and the main spatial patches of their populations were very similar between years. The size of the patches representing the dominant part of the abundance (80%) was mostly ecosystem- and species-specific. Occupation (area of presence) appears to be shaped by the extent of suitable habitats in each ecosystem whereas aggregation patterns (how the populations are distributed within the area of presence) were species-specific and related to levels of population biomass. In the upwelling area, both species showed consistently higher occupation values compared to the continental shelf area. Certain characteristics of the spatial distribution of sardine (e.g. spreading area, overlapping with anchovy) differed substantially between the two ecosystems. Principal component analysis of geostatistical and spatial indicators revealed that biomass was significantly related to a suite of, rather than single, spatial indicators. At the spatial scale of our study, strong correlations emerged between biomass and the first principal component axis with highly positive loadings for occupation, aggregation and patchiness, independently of species and ecosystem. Overlapping between anchovy and sardine increased with the increase of sardine biomass but decreased with the increase of anchovy. This contrasting pattern was attributed to the location of the respective major patches combined with the specific occupation patterns of the two species. The potential use of spatial indices as auxiliary stock monitoring indicators is discussed.