- Thumbnail
- Resource ID
- e70cfee2-68ab-11ec-8524-0242ac1c0006
- Title
- NAM CSR Fishing intensity for deep sea red crab fishing vessels
- Date
- Dec. 29, 2021, 1:33 p.m., Publication
- Abstract
- Fishing intensity of deep sea red crab fishing vessels
METHODS:
· VMS point location data for all vessels in each of the nine fisheries were collated for the
period 2014 – 2017. The data were cleaned, including removal of clear errors (e.g. points
on land) and clipped to the study area.
· Points were converted into a raster density layer, using a kernel density approach. This
used a 0.005° cell size and a 0.075° search distance using planar units.
· Density layers were then iteratively explored using a quantile based approach to identify
the cut-off for very low density use areas and areas used for transit only, which for all
industries identified the bottom 10% - 15% of used areas as being low use or transit only.
The calibration was done on an expert basis. It identified the mean density of transit only
zones, and then rounded this value up to the next 5 percentile mark. For the next steps
only values above this threshold were evaluated.
· Remaining areas were then split into 10 quantiles, from lower intensity use to highest
intensity use.
· The raster was then converted to a polygon layer.
· Isolated port and anchorage polygons (which would have had high intensity values as
vessels are often found there) were manually identified and exclude from the datasets.
· The above approach gives a set of 10 intensity of use categories from lower intensity use
(1) to highest intensity use (10). The areas deliberately exclude very low use areas.
- Edition
- --
- Responsible
- Anja
- Point of Contact
- Kreiner
- Anja.Kreiner@mfmr.gov.na
- Purpose
- --
- Maintenance Frequency
- None
- Type
- not filled
- Restrictions
- None
- License
- Public Domain
- Language
- eng
- Temporal Extent
- Start
- --
- End
- --
- Supplemental Information
- No information provided
- Data Quality
- --
- Extent
-
- x0: -798138.125000000000000
- x1: -85496.382812500000000
- y0: 6668096.000000000000000
- y1: 8134266.000000000000000
- Spatial Reference System Identifier
- EPSG:32734
- Keywords
- no keywords
- Category
- Fisheries
- Regions
-
Namibia