Title

Nautical area scattering coefficient (NASC) values attributed to anchovy in 2019

Date (Creation)

2023-06-01

Date (Publication)

2024-01-19

Citation identifier

https://sextant.ifremer.fr/record/4e0c8b6e-9050-4816-a5f3-457dae10c72d

Abstract

This map presents NASC values (Nautical Area Scattering Coefficient) attributed to anchovy (Engraulis encrasicolus) in 2019, highlighting the regional abundance gradient of this species. The map was created through IDW interpolation applied to the results of the MEDIAS surveys (MEDiteranean International Acoustic Survey) conducted in the Mediterranean in 2019.

Detailed information on the methodology for acquiring and processing acoustic data is available in the MEDIAS handbook. Additionally, details on the interpolation method used are provided in the report of the 16th working group meeting.

Credit

MEDIAS Working Group

Point of contact

Organisation name	Individual name	Electronic mail address	Role
IFREMER	Hattab Tarek	Tarek.Hattab@ifremer.fr	Local service desk
Mediterranean Acoustic Surveys in the framework of European Data Collection Regulation	MEDIAS		Author
IFREMER		sextant@ifremer.fr	Publisher
Mediterranean Acoustic Surveys in the framework of European Data Collection Regulation	MEDIAS		Production Unit

Thèmes Sextant

• /Biological Environment/Species/Fish Species of Commercial Interest

GEMET - INSPIRE themes, version 1.0

• Species distribution

Use limitation

CC-BY-NC-SA (Creative Commons - Attribution, No commercial usage, Sharing under the same conditions)

Access constraints

Copyright

Use constraints

Copyright

Spatial representation type

Grid

Language

English

Character set

UTF8

Topic category

• Oceans
• Biota
• Environment

Begin date

2019-06-10

End date

2019-10-31

Unique resource identifier

EPSG:4326

Number of dimensions

2

Dimension name

Column

Dimension size

977

Dimension name

Row

Dimension size

326

Cell geometry

Area

Transformation parameter availability

Distribution format

Name	Version

OnLine resource

Protocol	Linkage	Name
OGC:WMS	https://sextant.ifremer.fr/services/wms/medias_project	Regional_Anchovy_Map_2019
WWW:LINK	http://www.medias-project.eu	medias-project.eu
WWW:LINK	http://www.medias-project.eu/medias/website/handbooks-menu.html	MEDIAS_handbook
WWW:LINK	http://www.medias-project.eu/medias/website/meetingrep/func-startdown/235/	16th_report_working_group_meeting
FILE		Regional_Anchovy_Map_2019

Hierarchy level

Dataset

Statement

Split-beam echo-sounders were used for echo-sampling, operating at a frequency of 38 kHz and a pulse duration of 1 ms. The Elementary Distance Sampling Unit (EDSU) for echo integration was set at 1 nautical mile. Echoview or alternative Movies 3D software was employed for preprocessing acoustic data and conducting echo-integration.

Fish sampling was an essential component during surveys to obtain representative samples of the fish population for echo identification. Echo partitioning into species was based on echogram visual scrutinization, achieved either by direct allocation through the identification of individual schools or allocation based on representative fishing stations.

For the spatial interpolation of NASC values, the Inverse Distance Weighting (IDW) method was considered. Various values for the parameters p (power used in weighting) and n (number of nearest observations used for estimation) were tested. The optimal result was achieved with p=2 and n=10. Finally, to enhance the visibility of the local pattern on the interpolated surface, the color scale was developed using the "quantile" method.

Metadata

File identifier

4e0c8b6e-9050-4816-a5f3-457dae10c72d

Metadata language

Français

Other language

Language	Character encoding
English	UTF8

Character set

UTF8

Hierarchy level

Dataset

Date stamp

2024-05-21T08:53:13.626Z

Metadata standard name

ISO 19115:2003/19139 - SEXTANT

Metadata standard version

1.0

Metadata author

Organisation name	Individual name	Electronic mail address	Role
IFREMER	Hattab Tarek	Tarek.Hattab@ifremer.fr	Local service desk