Using genetic methods for analysis of fish meals and feeds employed in Greek mariculture

Abstract

Large quantities of high protein fish meals are needed to sustain cultured species and thus the impact to marine ecosystem has been highly discussed. The aim of this study was to apply a PCR-cloning methodology for a robust insight into the composition of commercial fish meals and feeds for farmed species of the Greek mariculture, assessing the risk posed by aquaculture to marine ecosystems but also the risk posed by commercial fish feeds to the increase in trophic level of species farmed in Greece. 89% of the sequences were identified to species level and only 11% to genus/family level. Overall, a total of 49 taxa were identified (44 fish species/taxon, five non-fish species/taxon). Even though small pelagic fish like Engraulis sp. were the main portion, a wide range of species constituted the fish meals and feeds. Plant and animal species were also detected as an alternative protein source. Feed products employed in Greek mariculture still contain large portions of fish meals which increase the mean trophic level of farmed species causing a farming up trend. The results emphasize that such molecular methodologies are needed to certify aquafeeds allowing fish feed producers to demonstrate their commitment to sustainable aquaculture. K E Y W O R D S16s rRNA gene, fish feed, fish meal, PCR-cloning

Genetic Identification and Traceability of Insect Meals

“…As mentioned above, the PCR-cloning methodology has been used successfully to analyze the composition of both fish and insect meals [40,42]. This approach allows for the species identification of individuals used for the preparation of insect meals; therefore, it allows for the control of their composition.…”

“…Non-targeted approaches based on cloning and next-generation sequencing (NGS) protocols allow for the analysis of the species composition, and sometimes, they can provide a quantitative aspect, even in processed products [40,41]. As regards insects, few cloning and NGS protocols have been developed to identify species in foods and feeds [42,43].…”

Applying global best practices for estimating unreported catches in Norwegian fisheries under a discard ban

“…On-board fishmeal production or offal processing facilities can also be used to intentionally hide illegal catches. Methods for identifying the species composition of highly processed products require genetic techniques which are rapidly developing, but the detection of low-represented species is still particularly difficult and costly, rendering it currently unfeasible to routinely screen landed fishmeal (Vlachavas et al 2019).…”

“…General applications of design-based estimators have been adapted for estimating discards and bycatches, producing best practice guidelines for various types of sampling (e.g. Anon 2003;ICES 2007a;Vigneau 2006). They acknowledge that the optimal procedure is highly case-specific, meaning there cannot be a simple, straight-forward method applicable generally.…”