Review and compilation of existing knowledge has been complemented with new data and analytical outputs. This includes establishing the main predator species and preys of mesopelagic species. Results show that mesopelagic fish species can feed on a high diversity of resources, and numerous trophic interspecific segregations appear to structure oceanic food webs. Species that appear to be close taxonomically or morphologically appear to have adopted different feeding strategies. It has been further obtained how all top predators depend to varying degrees on mesopelagic resources.
Reducing the uncertainty of the biomass estimations will require the combination of different methods. A “How to estimate mesopelagic biomass” guide has been produced. Using models, an estimation of the global biomass gives us a result that is 10-fold lower than previous estimations.
We have presented the first direct comparison of three key components of the Biological Carbon Pump at contrasting sites. Regarding these active fluxes it has been obtained that migratory mesopelagic fish are responsible for 9-28% of the total export of carbon to the twilight zone.
Novel insights into the identity and biogeography of potential microbial omega-3 producers has been developed based on metagenomic data mining. However, the exact products of the putative omega-3 biosynthetic gene clusters identified should be assessed further to verify their ability to produce these fatty acids. Most of the identified candidates remain uncultured, which implies that this is not a short-term route to obtain microbial PUFA suppliers. The mesopelagic layer is an interesting niche to find novel bioactive compounds. Furthermore, the gut microbiome of some mesopelagic fish species is dominated by potential omega-3 fatty acid producers, which could represent alternatives for omega-3 production relevant in the fields of nutraceuticals and aquaculture. Finally, we obtained how although technically feasible, financially processing fishmeal and oil or hydrolysates from mesopelagic fishes seems complex.
An economic analysis of whether it is worth exploiting or not the OTZ has been performed.
Through a literature review it has been screened the potential regulatory framework of fishing mesopelagics, both under the scope of RFMOs, high seas treaties, and under the EU fishing regulatory framework.
SUMMER partners have published 90 peer-reviewed articles. 103 data resources were published complying with the FAIR approach, including georeferenced data archived, genetic resources, and data and code. A school in which new scientists were trained in all aspects of the SUMMER research program, from data obtention to data treatment, including different techniques and on producing advice. In addition to the normal dissemination procedures through social media, we released the “Metropelagic” exhibition. At different metro stations in Bilbao, pictures of the mesopelagic diversity were exhibited. A symposium was organized, in where the main outputs of SUMMER were presented. A workshop with the industry was held in which interesting discussions around a potential mesopelagic fishery took place.
