CEFAS02fafc97-688e-4315-83bb-7503317a550f
English
dataset
Centre for Environment, Fisheries & Aquaculture Science
Data Manager
+44 (0)1502 562244
Cefas Lowestoft Laboratory
Pakefield Road
Lowestoft
Suffolk
NR33 0HT
UK
data.manager@cefas.co.uk
pointOfContact
2017-01-23T14:20:25
MEDIN Discovery Metadata Standard
Version 2.3.7
urn:ogc:def:crs:EPSG::4326
OGP
2010 - 2010 Centre for Environment, Fisheries & Aquaculture Science (Cefas) Bristol Channel 100mm codend trials 2010/11 - Fisheries Science Partnership
FSP Bristol Channel 100mm codend trials
2017-01-23
publication
CEFAS02fafc97-688e-4315-83bb-7503317a550f
http://www.cefas.co.uk/
This work was carried out as part of the Fisheries Science Partnership (FSP),
a Defra-funded collaborative programme of scientific research between the UK
fishing industry and scientists. Local trawlermen working in the Bristol
Channel in a mixed demersal fishery wanted to know whether an increase in
codend mesh size would be effective in reducing the levels of discards, and
whether its use would result in the loss of marketable fish.
Centre for Environment, Fisheries & Aquaculture Science
Data Manager
+44 (0)1502 562244
Cefas Lowestoft Laboratory
Pakefield Road
Lowestoft
Suffolk
NR33 0HT
UK
data.manager@cefas.co.uk
originator
Centre for Environment, Fisheries & Aquaculture Science
Data Manager
+44 (0)1502 562244
Cefas Lowestoft Laboratory
Pakefield Road
Lowestoft
Suffolk
NR33 0HT
UK
data.manager@cefas.co.uk
custodian
unknown
NDGO0005
Fish
Biota abundance, biomass and diversity
SeaDataNet P021 parameter discovery vocabulary
2011-03-25
revision
Species distribution
GEMET - INSPIRE themes, version 1.0
2008-06-01
publication
Public data (Crown Copyright) - Open Government Licence Terms and Conditions apply
otherRestrictions
Public data (Crown Copyright) - Open Government Licence Terms and Conditions apply
English
biota
SeaVoX Vertical Co-ordinate Coverages
2010-05-18
revision
Water column
-5
-2
51
52
2010-07-01T00:00:00.000Z
2010-10-31T00:00:00.000Z
http://data.cefas.co.uk/#/View/643/order
dataset
The gear used for the trials was a pair of twin-rig box trawls with 18 m
footropes, rigged on 10 and 12 inch rockhoppers. The trawls were coupled to 15
fathom split bridles which in turn were attached to a short length of sweep
(~5 fathoms). A set of A1, 6 foot otterboards were used to spread the trawls.
New codends were used in the trial for both the 80 mm control codends and the
100 mm test codends. Both the test and control codends were constructed of 4
mm diameter polyethylene twine and were of a standard length of 100 meshes. To
keep the cut-offs at the same length, the cut off rope was placed 30 meshes
from the last round on the test codend and 36 meshes from the last round on
the control codend. The mesh sizes of the codends were checked with the Omega
net-measuring gauge.
To account for seasonal variability in the catch, the fishing trials took
place over a period of four months, between July and October 2010. Four trips
of 1.5–3 days each were conducted. The trials followed the vessel’s normal
fishing pattern and were carried out in both daylight and darkness. Haul
duration was kept at 4 h where possible, to simulate normal fishing patterns.
Hauls were conducted off the North Devon coast, including Bideford Bay, West
of Lundy, and in the North and South Bristol Channel. The 80 mm and 100 mm
codends were fished simultaneously side-by-side on the twin-rig trawls. Cefas
scientific staff measured the lengths of all the fish caught in each haul,
with the catch from each codend measured separately. The crew sorted the catch
as they would normally do, and the retained fraction and discard fraction were
sampled separately. When catch volumes were high, a known fraction was
measured (i.e. the catch was sub sampled) and raised to provide an estimate
for the haul.