Development of new methods for assessment of fisheries management and spatial closures

Objectives, efforts and deliverables
The primary project objectives were to: i), identify new methods for detection of sensitive habitat-forming species and their associated communities; and ii), assess the suitability of new and existing methods to inform fisheries management and implementation of the Marine Strategy Framework Directive Descriptor 6 “Seafloor Integrity” and Descriptor 1 “Biodiversity of benthic habitats”.

The project efforts and outcomes were organised in three overarching components, which have also formed the backbone of the work packages and associated tasks in the project:
1. Field sampling of eDNA and benthic fauna of sensitive habitat-forming species, and of associated species, in areas closed and open to fisheries.
2. Modelling of distribution and density of sensitive habitat-forming species, and of the biodiversity of associated species, based on different sampling gears.
3. Development of eDNA methods for detection of identified sensitive benthic fauna species.

Based on these overarching project components, the following key deliverables were produced during the project period: i), sampling of eDNA water, sediment and fauna from 19 stations in the Northern Kattegat; ii), analyses of sensitive habitat-forming species distribution; iii), pilot analysis of density of individuals and density of species and biodiversity across sampling gears and stations; iv), detection and analyses of eDNA of sensitive species and correlation with faunal samples and v), conclusions and perspectives for suitability of monitoring methods to support fisheries and environmental management in Danish and EU waters.

Key results and conclusions
Data from a larger sediment sampler, the Van Veen grab (0.1 m 2), in combination with a towed underwater sledge recording video transects (approx. 480 m 2) provides a better representation of larger, sensitive benthic faunal species than data from the current Danish marine monitoring programme, NOVANA, which is based on the smaller HAPS corer alone (0.0143 m2). All molecular assays performed well, i.e., showed high sensitivity and potential for precise quantitative assessment of eDNA copy number. Moreover, new eDNA detection methods based on water and sediment samples provide an important supplementary sampling method, which may improve the efficiency and representativity of future monitoring of the environmental status of the investigated sensitive habitat-forming species.

Implementation and dissemination
With the above-described deliverables, the key project objectives have been met, and national stakeholders and governmental managers will profit from the project outputs: e.g., improved methods for detection of sensitive benthic faunal species as a basis for future environmental and fisheries management related to achieving Good Environmental Status (i.e., GES) in Danish marine waters. This will improve implementation of the Marine Strategy Framework Directive Development of new methods for assessment of fisheries management and spatial closures 6 Descriptor 6 “Seafloor Integrity” and associated Descriptor 1 benthic Biodiversity, especially related to future settings of GES thresholds for spatial extent and configuration of spatial closures of specific benthic Broad Habitat Types and their associated sensitive habitat forming species.

The project outcome will be disseminated through international scientific publications and via oral presentations of presented at meetings and graduate courses). Furthermore, contributions from the project have informed the work carried out in the international ICES FBIT, OSPAR and HELCOM working groups on identification and configuration of spatial closures (GES extent thresholds) and trade-offs between environmental conservation measures and fisheries resources and financial outcomes in Danish and European waters.