Identification

Title

2020 - 2020 Centre for Environment, Fisheries & Aquaculture Science (Cefas) Testing cod end and square mesh panel configurations in the English SW otter trawl fishery 2020/21 - Fisheries Science Partnership

Alternative title(s)

Report_67_ SW_demersal_trawl_selectivity _2020_21

Abstract

This work was carried out as part of the Fisheries Science Partnership (FSP) programme. The primary objective of the project was to obtain data on the differences between the currently permitted and proposed new trawl configurations, principally to move from the widespread use of 80mm mesh cod end to a default of 100mm. This information will help to provide evidence on the performance of more selective trawl configurations to inform on proposed changes to technical measures regulations in the southwest otter trawl mixed fishery. For this purpose, two trials lasting 6 days each took place in ICES Division 7e on the twin-rig otter trawler Rockfisher (SU6) in the months of October to December 2020. The vessel conducted simultaneous comparative tows of the control gear and two experimental gears. The first trial compared two trawls, both with 100mm cod ends, and one with an 80mm square mesh panel (SMP) and the other with 100mm SMP. A total of 19 paired hauls were collected for this trial. The second trial compared 100mm cod end with an 80mm SMP to an 80mm cod end with an 80mm SMP (as normally used by the vessel). A total of 14 paired hauls were completed for the second trial. At each station sampled, shot and haul, positional, times, depths and towing speed information were recorded, and for all species of fish length distribution data were taken, including collecting data on the benthic component of the catch.

Resource type

dataset

Resource locator

Unique resource identifier

code

CEFAS5efa0e00-6a3e-4e8f-b75d-49d7bbacbc2e

codeSpace

http://www.cefas.co.uk/

Dataset language

eng

Spatial reference system

authority code

OGP

code identifying the spatial reference system

urn:ogc:def:crs:EPSG::4326

Classification of spatial data and services

Topic category

Keywords

Keyword set

keyword value

Keyword set

keyword value

originating controlled vocabulary

title

reference date

date type

revision

effective date

2011-03-25

Keyword set

keyword value

originating controlled vocabulary

title

reference date

date type

publication

effective date

2008-06-01

Geographic location

West bounding longitude

-4

East bounding longitude

-0.5

North bounding latitude

51

South bounding latitude

50

Extent

Extent group

authority code

title

reference date

date type

revision

effective date

2010-05-18

code identifying the extent

Temporal reference

Temporal extent

Begin position

2020-09-10

End position

2020-01-31T23:00:00.000Z

Dataset reference date

date type

publication

effective date

2022-01-19

Frequency of update

notPlanned

Quality and validity

Lineage

A fixed routine for handling and sorting the catch was maintained throughout the trials. Catches from the two cod ends were always kept separate and were processed as either the retained or discarded fraction. Cefas observers sampled using standard techniques. For each haul, all fish species caught were measured to the nearest cm below. Sub sampling was necessary on occasions when the fish catch was large, and raising factors were calculated accordingly. Additionally, benthos was separated from the discarded fish, identified down to group level, and counted. The results were compiled in Excel and plotted graphically in R.

Conformity

Data format

name of format

version of format

Constraints related to access and use

Constraint set

Use constraints

Public data (Crown Copyright) - Open Government Licence Terms and Conditions apply

Constraint set

Limitations on public access

Public data (Crown Copyright) - Open Government Licence Terms and Conditions apply

Responsible organisations

Metadata on metadata

Metadata point of contact

contact position

Data Manager

organisation name

Centre for Environment, Fisheries & Aquaculture Science

full postal address

Cefas Lowestoft Laboratory

Pakefield Road

Lowestoft

NR33 0HT

UK

telephone number

+44 (0)1502 562244

email address

data.manager@cefas.co.uk

responsible party role

pointOfContact

Metadata date

2022-01-19T14:40:30

Metadata language