WORKING GROUP ON NEPHROPS SURVEYS (WGNEPS ; outputs from 2020)

The Working Group on Nephrops Surveys (WGNEPS) is the international coordination group for Nephrops underwater television and trawl surveys within ICES. This report summarizes the na-tional contributions on the results of the surveys conducted in 2020 together with time series covering all survey years, problems encountered, data quality checks and technological improve-ments as well as the planning for survey activities for 2021.ICE

Objective analysis of a coastal ocean eddy using satellite AVHRR and in situ hydrographic data

A common characteristic of the interaction between the coastal topography and eastern boundary currents (EBC) is the appearance of cold filaments and mesoscale eddies. Hydrographic and satellite temperature data obtained during a cruise on board R/V Point Sur off Point Arena, California, in May 1993 were analyzed to study a particular eddy field in this area. The hydrographic data was first used to verify the remotely sensed surface temperature field, using three dimensional data visualization. Selected vertical levels from each hydrographic station were then interpolated into a broader, finer resolution grid domain in preparation for an eventual model initialization, using multiquadric interpolation. The results verify the existence of the eddy and show its signature in the vertical to about 300 meters depth. A sensitivity study of interpolation parameters was performed to evaluate approximately the optimal set of parameters, showing that the multiquadric interpolation resolves very well the temperature field in the upper levels and introduces small amplitude, small scale noise in the deeper levels. This noise can be eliminated by a more thorough parameter sensitivity study.http://archive.org/details/objectiveanalysi00chumLieutenant, Portuguese NavyApproved for public release; distribution is unlimited

Kinematics and dynamics of a cyclonic eddy off Pt. Arena, California

In situ hydrographic data and remotely sensed sea surface temperature data were analyzed to describe the kinematics and dynamics of a cyclonic eddy observed off Point Arena, California, in May 1993. The hydrographic data were first objectively analyzed using multiquadric-biharmonic interpolation (M%B) to obtain a three- dimensional field of density. This was then used in a primitive equation (PE) model with a digital filter initialization method to arrive at the dynamically balanced three-dimensional velocity field, including the vertical motion. Several aspects related to geostrophic adjustment, to data analysis and to the lack of exact synopticity in the observations were examined; these include the effects of internal tides, eddy rotation and MQ-B parameters sensitivity analysis. The results reveal a cyclonic circulation with meanders in the otherwise nearly circular flow, and maximum horizontal speeds of about 40-5O cm/s at the surface. The meanders have associated patterns of radially aligned patches of sinking and rising motion, extending coherently to about 500 m depth, with maximum vertical velocities of 2022 m/day between 100 and 150 m depth. Because of the strong horizontal currents and the short horizontal length scales involved, the particle vertical excursions are very small.http://archive.org/details/kinematicsnddyna1094542791Portuguese Navy authorApproved for public release; distribution is unlimited

Outside the Academia

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ResourceCODE framework: A high-resolution wave parameter dataset for the European Shelf and analysis toolbox

Resource mapping is a key element in the planning and consequent deployment of Offshore Renewable Energy (ORE) converters. A proper characterization of the environmental forcing enables the optimization of energy extraction and a more accurate assessment of the structural loading. This contributes to improving reliability and extending the operational life of devices at a given extraction site. Providing an accurate characterisation of the environmental loading is subjected to the availability and quality of relevant datasets, which are either obtained from measurements, in-situ or via remote sensing, or from numerical models. Then, the adequate use of these datasets relies on the analysis’ tools and selected methods which allow an appropriate description of the underlying physics. This paper presents the high-resolution wave hindcast database extending across European waters and developed to be the reference dataset of the ResourceCODE Marine Data Toolbox, designed to provide a full suite of tools to support ocean energy analytics.

New monitoring technologies to produce ancillary data on Nephrops stock assessment

Working Group on Nephrops Surveys (WGNEPS), 6-8 November 2018, Lorient, France.-- 2 pages, 2 figuresCurrent stock assessment based on UWTV surveys counts of Nephrops burrows (and thus inhabiting individuals) based on the peculiar morphological traits of these structures within the substrate. Three major uncertainties have been identified in this methodology: i. burrow occupancy which is currently assumed to be of one individual >17mm carapace length per identifiable burrow system; ii. burrow system size and the “edge effect” which could bias the estimates of effective area surveyed; iii. Burrow identification because other sympatric fish and decapod species construct tunnels with morphology similar to those of Nephrops. It is therefore of relevance to produce data on burrow emergence to validate or improve the assumptions made in the UWTV assessment methodology. New in situ technological applications should be used to monitor burrowing behavior producing data on the following key aspects: i. Burrow persistence related to the death and opportunistic occupation by other species; ii. Burrow emergence rhythms at different time-scales which oblige to perform surveys in specific time windows (tidal, day and seasons); iii. Emergence duration that varies according to the hunger state (predation-scavenging), predator presence (visual contact, odor plumes, noise) and intraspecific interactions (territoriality); and finally, iv. emergence range, identifying how many holes belong to a single anima

New monitoring technologies assisting deep-water and deep-sea crustacean decapods stock assessment

The Crustacean Society Mid-Year Meeting (TSC 2019), 26-30 May 2019, Hong Kong.-- 1 pageThe stock assessment of Norway lobster (Nephrops norvegicus) is made by fishery-dependent (i.e. trawl catches) or fishery-independent (i.e. burrow counts) methods. In both cases, important methodological assumptions affect the validity of derived population demographic estimates. Here, we provide a description of cabled underwater sensor networks in relation to the production of ancillary data for stock assessment of deep-sea highly commercially exploited decapods, whose fishery is in decline in the Mediterranean Sea. Specifically, two 20 m depth cabled video-observatories belonging to the European Multidisciplinary Seafloor and water column Observations (EMSO) network (SmartBay, in Ireland and OBSEA in Spain) are being used for in situ high-frequency time-lapse video and oceanographic monitoring of the burrow emergence of individuals. This monitoring will be used to quantify inter-individual variability in frequency and duration of emergence as a product of ecological and environmental forcing, and inform population level estimates of emergence (and hence availability to trawling) and burrow occupancy. Obtained data will serve as cross validation for acoustic tagging trials (i.e. animals bearing frequency-specific emitters, operating in tandem with listening hydrophone stations). Emissions and silences will be proxy of emergence timing and duration. A shallow water trial performed at OBSEA will serve as test-bed for acoustic mooring placement at 350-400 m depth, in the no take zone off Blanes Canyon (Spain)The present work was supported by RESBIO (TEC2017-87861-R) and RESNEP (CTM201782991-C2-1-R) as well as TNAs: ADVANCE (H2020-INFRAIA-2014-2015 under the Grant Agreement no. 654410, JERICO-NEXT) and SmartLobster (EMSO-LINK)

The potential of video imagery from worldwide cabled observatory networks to provide information supporting fish-stock and biodiversity assessment

15 pages, 4 figures, supplementary material https://doi.org/10.1093/icesjms/fsaa169.-- There are no new data associated with this article. No new datawere generated or analysed in support of this researchSeafloor multiparametric fibre-optic-cabled video observatories are emerging tools for standardized monitoring programmes, dedicated to the production of real-time fishery-independent stock assessment data. Here, we propose that a network of cabled cameras can be set up and optimized to ensure representative long-term monitoring of target commercial species and their surrounding habitats. We highlight the importance of adding the spatial dimension to fixed-point-cabled monitoring networks, and the need for close integration with Artificial Intelligence pipelines, that are necessary for fast and reliable biological data processing. We then describe two pilot studies, exemplary of using video imagery and environmental monitoring to derive robust data as a foundation for future ecosystem-based fish-stock and biodiversity management. The first example is from the NE Pacific Ocean where the deep-water sablefish (Anoplopoma fimbria) has been monitored since 2010 by the NEPTUNE cabled observatory operated by Ocean Networks Canada. The second example is from the NE Atlantic Ocean where the Norway lobster (Nephrops norvegicus) is being monitored using the SmartBay observatory developed for the European Multidisciplinary Seafloor and water column Observatories. Drawing from these two examples, we provide insights into the technological challenges and future steps required to develop full-scale fishery-independent stock assessmentsThis work was funded by the following project activities: ARIM (Autonomous Robotic sea-floor Infrastructure for benthopelagic Monitoring; MartTERA ERA-Net Cofound), ARCHES (Autonomous Robotic Networks to Help Modern Societies; German Helmholtz Association), RESBIO (TEC2017-87861-R; Ministerio de Ciencia, Innovación y Universidades, Spanish Government), RESNEP (CTM2017-82991-C2-1-R; Ministerio de Ciencia, Innovación y Universidades, Spanish Government), and SmartLobster (EMSO-LINK Trans National Access-TNA). The EMSO_SmartBay cabled observatory was funded by Science Foundation Ireland (SFI) as part of a SFI Research Infrastructure Award Grant No. 12/RI/2331With the funding support of the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019-000928-S), of the Spanish Research Agency (AEI