International Bottom Trawl Survey Working Group (IBTSWG). ICES Scientific Reports, 04:65

The International Bottom Trawl Survey Working Group (IBTSWG) coordinates fishery-independent bottom trawl surveys in the ICES area in the Northeast Atlantic and the North Sea. These long-term monitoring surveys provide data for stock assessments and facilitate examina-tion of changes in fish distribution and relative abundance. The group also promotes the stand-ardization of fishing gears and methods as well as survey coordination. This report summarizes the national contributions in 2021–2022 and plans for the 2022–2023 surveys coordinated by IBTSWG

The contribution of mesh opening angle to the drag of netting panels

Highlights • a high-fidelity RANS CFD method is used to simulate the flow through netting panels. • The influence of netting solidity, twine diameter, mesh opening angle and incident angle is examined. • Mesh opening angle, solidity and angle of incidence greatly influence the hydrodynamic force coefficients and efficiency. To ensure the economic and environmental sustainability of the fisheries and aquaculture industries, it is necessary to address issues related to fuel consumption, environmental degradation, and fish welfare. Hence, we need a thorough understanding of the filtration efficiency and the hydrodynamic forces acting on towed fishing gears and netting structures. Here we apply a Reynolds-averaged Navier-Stokes (RANS) CFD method to model the flow through netting panels, where we vary the operational and design parameters of flow speed, netting solidity, twine diameter, mesh opening angle and the incidence angle of the flow to the panel. Thus, we create a simulated data set which we analyze to provide a fundamental understanding of the functional relationships for the pressure drop and tangential drag coefficients, and the flow deflection in terms of these parameters. We pay particular attention to the effect of mesh opening angle, a parameter that has not received much attention in the literature. We demonstrate that it has a large influence on the drag and lift coefficients and consequently on the hydrodynamic efficiency of netting panels. These results will be particularly useful for reducing the hydrodynamic forces on netting structures and improving the fuel efficiency of towed fishing gear operations

Workshop on the Further Development of the New IBTS Gear (WKFDNG). ICES Scientific Reports. 4:18

The standard gear for the International Bottom Trawl Survey (IBTS), a fisheries-independent research survey originating from the 1960s, will be replaced. The long-term monitoring pro-vides data on commercial pelagic and demersal fish species for stock assessments and facili-tates examination of changes in fish distribution and abundance. The remit of this Workshop on the Further Development of the New IBTS Gear (WKFDNG) was to design a simple gear, as standardised as possible, robust, and easy to maintain. Additionally, the workshop was tasked to provide input for the roadmap towards implementation of the new gear