1996 - Centre for Environment, Fisheries & Aquaculture Science (Cefas) Nephrops underwater TV Surveys - VHS and DVD footage
Nephrops burrow counts
Underwater TV (UWTV) surveys are carried out in the Eastern Irish Sea and North Sea to record the occurrence of Nephrops ( *Nephrops* *norvegicus* ) burrows. This information forms the basis of the Nephrops assessment to develop fishery independent indicators of stock size, exploitation status and catch advice. The standard methodology involves the use of a sledge mounted camera to film the seabed at a fixed set of stations conducting TV tows for 10 minutes.
dataset
http://data.cefas.co.uk/#/View/3020/
function: order
CEFAS7c66106f-2073-437a-8470-0fc8e59fb91a
http://www.cefas.co.uk/
eng
OGP
urn:ogc:def:crs:EPSG::4326
oceans
revision
2011-03-25
publication
2008-06-01
publication
2008-06-01
-4.5
4
55.75
53.5
revision
2010-05-18
revision
2010-05-18
1996
2016-07-14T12:28:10.100
publication
2016-07-14
annually
The full dataset consists of approximately 160+ VHS tapes (1996 to 2002) and 260+ DVD discs (2003 to present) plus additional back-up tapes. The DVD discs are kept for reference and quality-control purposes at Cefas, Lowestoft, for a period of 5 years, after which they may be disposed of. The VHS tapes are now obsolete but will be retained until January 2017 at which time they may be disposed of. Material can be made available upon request (please contact data steward for more information). Linked below is a training presentation and video used by Cefas as an example of the format and quality of the footage. Two additional metadata records entitled 'Nephrops underwater TV Surveys in the Eastern Irish Sea (video data and database)' and 'Nephrops underwater TV Surveys in the North Sea (video data and database)' describe region-specific data. In line with SGNEPS (Study Group on Nephrops Surveys) recommendations all scientists are trained/re-familiarised using training material and validated using reference footage (measured by Linn’s concordance correlation coefficient (CCC)) prior to recounting each survey footage. A limit of 0.5 is used to identify counters who need further training. On completion of this process, all survey recounts are conducted, as blind counts, by two persons during the survey. Here, the number of Nephrops burrow systems and the activity in and out of the burrows are counted by each minute block (for 7 clear minutes). In cases where the field of view became obscured by cloud, the number of seconds obscured are recorded and all minute blocks with more than 20 seconds obscured are rejected for analysis. After all counts completed again the Linn’s CCC is again applied to check which stations needed to be revisited and were a 3rd or 4th counter needed to be added. Whilst reviewing the videos, the visibility, ground type, trawl marks, occurrence of bio-fauna, ground contact of the sledge, cloud and any other interference is recorded during each one-minute intervals, using a classification key.
Public data (Crown Copyright) - Open Government Licence Terms and Conditions apply
Public data (Crown Copyright) - Open Government Licence Terms and Conditions apply
Data Manager
Centre for Environment, Fisheries & Aquaculture Science
Cefas Lowestoft Laboratory
Pakefield Road
Lowestoft
NR33 0HT
UK
+44 (0)1502 562244
originator
Data Manager
Centre for Environment, Fisheries & Aquaculture Science
Cefas Lowestoft Laboratory
Pakefield Road
Lowestoft
NR33 0HT
UK
+44 (0)1502 562244
custodian
Data Manager
Centre for Environment, Fisheries & Aquaculture Science
Cefas Lowestoft Laboratory
Pakefield Road
Lowestoft
NR33 0HT
UK
+44 (0)1502 562244
pointOfContact
2016-07-14T12:28:23