Identification

Title

2021 Scallop Underwater TV Survey in the North Sea

Abstract

King scallop (*Pecten maximus*) underwater TV (UWTV) survey carried out in the North Sea by RV Cefas Endeavour in 2021. A drop frame mounted camera was used to record high definition (HD) video and numerous still photo images of the seabed for 20 minute tows. Observations of scallops were recorded by trained staff. These data are used to estimate biomass in areas that are not fished by the fishing fleet, but support populations of scallops and which may contribute to recruitment in dredged areas. This complements data collected as part of the wider scallop stock assessment in the region. Each sampling station has associated positional and ancillary data (e.g. salinity and temperature).

Resource type

dataset

Resource locator

https://data.cefas.co.uk/view/21481

name: Cefas Data Portal

description: The Cefas Data Portal contains metadata records and data sets available to download and connect to in support of our commitment to open science. Data is available in the following formats: Binary download, CSV.

function: download

Unique resource identifier

code

CEFAS21481

codeSpace

https://data.cefas.co.uk

Dataset language

eng

Spatial reference system

code identifying the spatial reference system

Classification of spatial data and services

Topic category

biota

Keywords

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

revision

effective date

2011-03-25

Keyword set

keyword value

originating controlled vocabulary

title

reference date

date type

publication

effective date

2008-06-01

Keyword set

keyword value

originating controlled vocabulary

title

reference date

date type

revision

effective date

2010-05-18

Keyword set

keyword value

originating controlled vocabulary

title

reference date

date type

publication

effective date

2012-01-11

Keyword set

keyword value

originating controlled vocabulary

title

reference date

date type

publication

effective date

2012-01-11

Geographic location

West bounding longitude

-0.50

East bounding longitude

3.00

North bounding latitude

54.75

South bounding latitude

53.25

Temporal reference

Temporal extent

Begin position

2021-05-14

End position

2021-05-21

Dataset reference date

date type

publication

effective date

2022-06-08

date type

revision

effective date

2023-08-22

date type

creation

effective date

2022-05-30

Frequency of update

notPlanned

Quality and validity

Lineage

The survey deployed the STR SEASPYDER, which is an acquisition system that allows uninterrupted recording of high definition (1920x1080 resolution at 25 frames per second) video footage along with high definition (18 megapixel) photography and interfacing telemetry data of depth, heading and altitude from the seabed. The stills camera is fitted with 18-megapixel digital single-lens reflex (SLR) camera that offers total control for all photographic parameters (focus, shutter speed and aperture) synchronised with a STR subsea strobe that provide the correct illumination to obtain the stills. The drop frame has attached six LED underwater lamps and two dot and two-line lasers used as size reference. Additionally, the drop frame has mounted a data logger that records temperature, pressure, and salinity. The data logger is plugged to a fluorometer and an optical dissolved oxygen sensor. Real-time data are transferred through a fibre optic cable mounted in a winch in the port side of the research vessel (RV) directly to the surface unit for visualisation in the ships main laboratory. This includes high definition (HD) video, photos, telemetry (depth, heading and altitude) and imaging sonar. The surface unit also has a software, used as interface for the control of a whole system, for adding an overlay to the footage. This overlay shows the ID for each station, transect and the telemetry data for their posterior analysis and visualization. Beds where scallop fishing takes place had already been defined for scallop dredge surveys. For underwater television (UWTV), survey area boundaries were defined as likely scallop ground (from habitat modelling), as well as areas considered by industry to contain scallop populations but cannot be fished due to unsuitable ground type, conservation management, or gear conflict issues. Once the un-dredged zones had been determined, random positions were selected. A random stratified sampling design was used. As it is not clear if scallop density is randomly distributed across the whole bed, it was considered important to ensure broad spatial coverage of the sampling design. Therefore, within each bed, blocks were used to represent the different strata. Broad spatial coverage is provided by ensuring that most blocks are sampled. Within each block, one valid cell was selected at random, the midpoint of which is a potential sampling position. The drop frame was towed at 0.4 knots, with a track duration of 20 minutes resulting in a distance covered of just under 250 m. An altimeter on the drop frame enabled it to be maintained at a relatively consistent depth of 0.5 m above the seabed. Field of view was determined by the view within the drop frame (~1.35 m), and determination of scale was facilitated by point lasers fitted to the camera mounts to mark a consistent distance on the seabed. The angle of the cameras to seabed was approximately 53°. Video images were viewed live on board the RV and all observed scallops counted. Digital stills were manually taken when scallops or indications of scallops were observed to provide more detailed images for subsequent count confirmation. Video footage was reviewed later by trained staff for additional verification and following a standard procedure. Median counts per transect were standardised to area.

Conformity

Conformity report

specification

title

reference date

date type

publication

effective date

2013-12-10

degree

false

explanation

See the referenced specification

Conformity report

specification

title

reference date

date type

publication

effective date

2010-12-08

degree

true

explanation

See the referenced specification

Data format

name of format

Unknown

version of format

Constraints related to access and use

Constraint set

Limitations on public access

Constraint set

Limitations on public access

Responsible organisations

Responsible party

organisation name

Centre for Environment, Fisheries and Aquaculture Science, Lowestoft Laboratory (CEFAS)

full postal address

Cefas Lowestoft Laboratory

Pakefield Road

Lowestoft

NR33 0HT

UK

email address

data.manager@cefas.co.uk

responsible party role

originator

Responsible party

organisation name

Centre for Environment, Fisheries and Aquaculture Science, Lowestoft Laboratory (CEFAS)

full postal address

Cefas Lowestoft Laboratory

Pakefield Road

Lowestoft

NR33 0HT

UK

email address

data.manager@cefas.co.uk

responsible party role

custodian

Responsible party

organisation name

Centre for Environment, Fisheries and Aquaculture Science, Lowestoft Laboratory (CEFAS)

full postal address

Cefas Lowestoft Laboratory

Pakefield Road

Lowestoft

NR33 0HT

UK

email address

data.manager@cefas.co.uk

responsible party role

distributor

Responsible party

organisation name

Department for Environment, Food and Rural Affairs (DEFRA)

email address

defra.helpline@defra.gov.uk

responsible party role

owner

Metadata on metadata

Metadata point of contact

organisation name

Centre for Environment, Fisheries and Aquaculture Science, Lowestoft Laboratory (CEFAS)

full postal address

Cefas Lowestoft Laboratory

Pakefield Road

Lowestoft

NR33 0HT

UK

email address

data.manager@cefas.co.uk

responsible party role

pointOfContact

Metadata date

2023-08-22T11:16:22

Metadata language