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Swept Area Ration and interannual Variation (2012-2016)


Metadata
File Identifier: 42F8623B-72EF-4A2A-8734-2FF60E7EFDB1-MS
Metadata Language: English
: utf8
Resource Type: Service
Responsible Party:
Individual Name: Ulrike Kleeberg
Organisation Name: HZG Helmholtz-Zentrum Geesthacht
Role: Point Of Contact
Contact Info:
E-Mail Address: ulrike.kleeberg@hzg.de
Responsible Party:
Individual Name: Rabea Diekmann
Organisation Name: Thünen Institut
Role: Point Of Contact
Contact Info:
Delivery Point: Herwigstraße 31
City: Bremerhaven
Administrative Area: Bremen
Postal Code: 27572
Country: DE
E-Mail Address: Rabea.Diekmann@ti.bund.de
Metadata Date: 2018-02-15
Metadata Standard Name: INSPIRE Metadata Implementing Rules: Technical Guidelines based on EN ISO 19115 and EN ISO 19119
Metadata Standard Version: V. 1.2
Service Identification
Abstract: The footprint of bottom trawling was estimated from Vessel monitoring by satellite (VMS) data, linked to the corresponding logbook information (German fleet) or the European fleet register (international fleet), respectively. It is quantified as annual swept area ratio, which is the ratio between the cumulative area touched by trawls and the size of the respective grid cell (0.05°*0.05°). Thus, a swept area ratio of 1 means that an area equivalent to the size of the grid cell was fished over one year. We considered the gear-specific footprints of four major gear groups: otter trawls, demersal seines, beam trawls and dredges. Further the swept area ratio is averaged over a period from 2012-2016 and thus represents the overall picture of fishing pressure to the seafloor in those years.The second map illustrates the coefficient of variation of annual swept area ratios from 2012-2016. It thus corresponds to the map “Footprint of bottom trawling in the German EEZ of the North Sea (2012-2016)” and represents the interannual variation in fishing pressure by bottom trawling.
Purpose: Footprint of bottom trawling in the German EEZ of the North Sea (2012-2016) and interannual variation in the footprint of bottom trawling in the German EEZ of the North Sea (2012-2016)
Thumbnail:
Browse Graphic: https://coastmap.hzg.de/server/rest/directories/thumbs/TI_SAR.png
Citation:
Title: Swept Area Ration and interannual Variation (2012-2016)
Date:
Date: 2018-02-05
Date Type: Creation Date
Date:
Date: 2018-02-15
Date Type: Publication Date
Identifier: 42F8623B-72EF-4A2A-8734-2FF60E7EFDB1-DS
Individual Name: Rabea Diekmann
Organisation Name: Thünen Institut
Role: Principal Investigator
Contact Info:
Delivery Point: Herwigstraße 31
City: Bremerhaven
Administrative Area: Bremen
Postal Code: 27572
Country: DE
E-Mail Address: Rabea.Diekmann@ti.bund.de
Point Of Contact:
Individual Name: Rabea Diekmann
Organisation Name: Thünen Institut
Role: Processor
Contact Info:
Delivery Point: Herwigstraße 31
City: Bremerhaven
Administrative Area: Bremen
Postal Code: 27572
Country: DE
E-Mail Address: Rabea.Diekmann@ti.bund.de
Keyword Collection:
Keyword: Swept Area Ratio
Keyword: fishery
Keyword: pressureKey5
Keyword: TI
Keyword: NOAH
Keyword: Coefficient Variation
Keyword: Live Data and Maps
Service Type: ESRI ArcGIS Mapping Service
Service type version: 1.1.3
Extent:
West Bounding Longitude: 3.312577
East Bounding Longitude: 9.031055
North Bounding Latitude: 55.944878
South Bounding Latitude: 53.378681
West Bounding Longitude: 3.312577
East Bounding Longitude: 8.511855
North Bounding Latitude: 56.003605
South Bounding Latitude: 53.531742
Constraints: The swept area ratio can only be an approximate value to quantify the pressure of bottom trawling on the seafloor. The map should be interpreted together with information about the interannual variation (CV).
Legal Constraints:
Access Constraints: Restricted
Use Constraints: Restricted
Other Constraints: not to be used without prior consultation of the point of contact
Distribution
Distribution Format:
Format Name: ArcGIS Service
Format Version: 10.5.1
Transfer Options:
URL: http://coastmap.hzg.de/server/rest/services/NOAH_geoDB/TI_SAR/MapServer
Protocol:
Application Profile:
Function: Information
Transfer Options:
URL: http://coastmap.hzg.de/server/services/NOAH_geoDB/TI_SAR/MapServer/WMSServer?
Protocol:
Application Profile:
Function: Information
Quality
Scope: Dataset
Conformance Result:
Validation Performed: true
Explanation:
Specification:
Title: INSPIRE Directive 2007/2/EC
Date:
Date: 2018-02-28
Date Type: Publication Date
Lineage: The swept area ratio was calculated with data from three different sources: The Vessel Monitoring by Satellite (VMS), German logbook data and the European Fleet Register (http://ec.europa.eu/fisheries/fleet/index.cfm). Within the German EEZ, VMS data from all vessels larger than 12m length is accessible (since 2012). In order to distinguish between gear types, either logbook information or the primary gear of each ship was taken from the fleet register as well as ship length and engine power. VMS-data were analysed using the VMStools package (Hintzen et al., 2012), which is available as add-on package for the R software (R Core Team 2013), and only position data, which were associated to fishing activities were used in the mapping process. Notes and Limitations: The swept area ratio can only be an approximate value to quantify the pressure of bottom trawling on the seafloor. First of all, calculations were based on the assumption that all vessels, where logbook information was missing, used exclusively their primary gear listed in the fleet register. Because gear designs differ not only in their size, which is considered as gear width, but also in their bottom contact (e.g. by tickler chains), the physical trawling impact is not equivalent to the swept area ratio. Further, the swept area is not equivalent to the proportion of the cell that was impacted by the gear (unless fishing tracks do not overlap at all). Here data were averaged over a period of five years (2012-2016). Any long-term changes, such as area closures due to construction of offshore windfarms, may be not yet visible. The map should be interpreted together with information about the interannual variation (CV).
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