Seafloor litter - Density per trawl per year (Nb Items/km²)

This visualization product shows the density of seafloor litter per trawl per year.

EMODnet Chemistry included the gathering of marine litter in its 3rd phase. Since the beginning of 2018, data of seafloor litter collected by international fish-trawl surveys have been gathered and processed in the EMODnet Chemistry Marine Litter Database (MLDB). The harmonization of all the data has been the most challenging task considering the heterogeneity of the data sources, sampling protocols (OSPAR and MEDITS protocols) and reference lists used on a European scale. Moreover, within the same protocol, different gear types are deployed during fishing bottom trawl surveys.

To calculate the density, the swept area of the trawl is required. The swept area is calculated from the wingspread (which depends on the fishing gear type) and the distance trawled. In the cases were the wingspread and/or the trawled distance are unknown, effective values were calculated from available information, when possible, specifically, the distance:
Distance =Haul duration Ground speed While the calculation of the effective wingspread is based in a general formula (van Hal, 2017) which considers other parameters known of the net, thus introducing some inaccuracies: Wingspread=doordpread0.18870+5.87280 Doorspread = 14.2 * log(Depth) = 16.72 * log(Warp_length) + 18.49 This method may be improved in the future. The used formula for the swept area and density is: Density (number of items per km²)= (∑number of items)/(Swept area)

Percentiles 50, 75 & 95 have been calculated taking into account data from all years.

More information is available in the document attached.

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    Seabed litter - Density (Nb. Items/km2)

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    Seabed litter - Density (Nb. Items/km2)

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Additional Info
Field Value
access_constraints ["Usage is subject to mandatory citation: \"This resource was generated in the framework of EMODnet Chemistry, under the support of DG MARE Call for Tender EASME/EMFF/2016/006 - lot4.\""]
bbox-east-long 22.2
bbox-north-lat 61.756
bbox-south-lat 36.0183
bbox-west-long -15.397
contact-email office@alpha.rmri.ro
coupled-resource
[]
dataset-reference-date
[{"type": "creation", "value": "2019-03-05"}]
frequency-of-update
graphic-preview-file https://sextant.ifremer.fr/geonetwork/srv/api/records/afe2d718-41e6-4bb4-95f5-ad836a45c891/attachments/seabed_abondance.JPG
GUID afe2d718-41e6-4bb4-95f5-ad836a45c891
licence []
metadata-date 2019-07-11T10:09:12
metadata-language eng
point_of_contact 1 office@alpha.rmri.ro
point_of_contact 2 sismer@ifremer.fr
point_of_contact 3 nodc@ogs.trieste.it
point_of_contact 4 morgan.le.moigne@ifremer.fr
progress
resource-type series
responsible-party
[{"name": "IFREMER / STATION DE SETE", "roles": ["originator"]}, {"name": "IFREMER / IDM / SISMER - Scientific Information Systems for the SEA", "roles": ["resourceProvider"]}, {"name": "UNKNOWN", "roles": ["originator"]}, {"name": "National Institute for Marine Research and Development \"Grigore Antipa\"", "roles": ["originator"]}, {"name": "OGS (Istituto Nazionale di Oceanografia e di Geofisica Sperimentale), Division of Oceanography", "roles": ["resourceProvider"]}, {"name": "Ifremer / VIGIES (Information Valuation Service for Integrated Management and Monitoring)", "roles": ["resourceProvider"]}]
spatial {"type": "Polygon", "coordinates": [[[-15.397, 36.0183], [22.2, 36.0183], [22.2, 61.756], [-15.397, 61.756], [-15.397, 36.0183]]]}
spatial-data-service-type
spatial-reference-system WGS 84 (EPSG 4326)
spatial_harvester true
system:type Series
temporal-extent-begin 2006-10-01
temporal-extent-end 2018-08-16
topic_category oceans
Management Info
Field Value
Author EMODnet Chemistry
Maintainer bluebridge_catalogue_one
Last Updated 24 December 2019, 00:14 (CET)
Created 24 December 2019, 00:14 (CET)