Status and progress in WP2 by month 36

Summary

In work package 2, Survey and sampling technology development, the partners have focused on development, implementation and field testing of new technology and methodology for accurate quantification of mesopelagic macroplankton and micronekton resources. Experiences from this work, as well as the collected field data, will form an important basis for the future works toward defining a protocol for monitoring of mesopelagic resources.

Highlights from the field data so far include new information on acoustic properties of mesopelagic scatterers, as well as novel data on organismal densities inside and outside of the deep scattering layers. In this second reporting period the work in WP2 included a field and literature study of the behaviour of mesopelagic species to trawls and submersible platforms like towed vehicles. The protocol for abundance estimation of biomass and diversity in the mesopelagic zone was finalized. The protocol constitutes a large work on methods for scientific assessment of abundance and biomass in the mesopelagic zone, with focus on both common and specific pitfalls and uncertainties introduced by the different methodologies. Traditional as well as new technologies were reviewed. Besides public videos on best survey and capture practices this has also included production of a public e-Learning-webinar-video on vertical capture strategies which discusses different capture strategies for quantifying mesopelagic resources.

Highlights

• High resolution acoustic data sampled at mesopelagic depths provide insight into densities and acoustic properties of mesopelagic micronekton.
• Direct acoustic estimation of mesopelagic biomass has been demonstrated using a novel combination of broadband acoustic data and a theoretical scattering model.
• Non-graded trawl designs developed allow more accurate survey sampling of mesopelagic micronekton.
• Improved trawl instrumentation allows a better understanding of results from trawl sampling.
• The behaviour of mesopelagic species to trawls and submersible platforms.
• Protocol for abundance estimation of biomass and diversity in the mesopelagic zone.
• Webinars on capture strategies for quantifying mesopelagic resources.