1987 - 1987 Centre for Environment, Fisheries & Aquaculture Science (Cefas) North Sea Plankton Survey - RV Clione 06/87
A series of five surveys were carried out between May and September of 1987 in the North Sea off the north-east coast of England to undertake stock assessment by the egg production method. The species targeted were *Nephrops norvegicus* (Norway lobster) and *Homarus gammarus * (European lobster) with plankton samples being collected at each site on a planned survey grid. The data described here consists of the numbers of eggs and larvae, along with associated positional and ancillary data and volumes filtered.
dataset
http://data.cefas.co.uk/#/View/3784/
function: order
CEFASca7c4ea8-a872-476d-9537-b4d46be55832
http://www.cefas.co.uk/
eng
OGP
urn:ogc:def:crs:EPSG::4326
biota
revision
2011-03-25
publication
2008-06-01
publication
2008-06-01
-2
1
56.5
54.25
revision
2010-05-18
1987-05-08
1987-05-13
publication
2020-01-30
notPlanned
Gear used for these cruises were: 76cm high speed tow net (HSTN) with a 40cm diameter nose cone, MIK net and neuston net, Sampler deployment: The HSTN sampler was deployed in a double oblique tow from the surface to within 2 m of the seabed. Veering and hauling speeds were manually adjusted to ensure that each depth band was sampled equally. At shallow stations, multiple double oblique dives were necessary to enable a sufficient volume of water to be filtered. A minimum sampler deployment time of 15 minutes was aimed for. On recovery, the net was carefully washed down and the sample collected from the end bag. Each sample was then fixed using buffered formaldehyde solution and transported to the participating laboratories for sorting and identification. Sample analysis: Fish eggs and larvae were picked out from all samples by eye and, whenever practicable, the whole sample was sorted. However sub-sampling was at times necessary. Sub-sampling was carried out using a Folsom splitter. Fish larvae were readily identified unless they had been badly damaged during collection or were prematurely hatched. For some groups such as the sandeels (Ammodytidae) and the group of Gadidae commonly called rocklings, individuals were not identified to the species level. Fish eggs were initially split into three groups on the basis of the presence or absence of oil globules. Those containing either a single or many oil globules could usually be identified to the species level. Eggs with no oil globules were more difficult to identify. Some of these species such as cod ( *Gadus morhua* ), sprat ( *Sprattus sprattus* ), long rough dab ( *Hippoglossoides platessoides* ), dragonet ( *Callionymus* spp.) and plaice ( *Pleuronectes platessa* ) were identified because of their size or unique features. Unidentified eggs in this group were recorded as egg diameters. Data storage: The raw data were stored on an Access database. The various data files were stored on the database in a series of tables linked by having the content of certain fields in common. All routine calculations, calibration changes and conversions were carried out on the database. The data tables (but not queries etc.) have now been extracted into text files. Plankton data are normally expressed as either number of organisms per m3 or per m2. The number per m3 is obtained by dividing the numbers per sample by the volume filtered, calculated from the sampler flowmeters. Number per m2 is obtained by multiplying the number per m3 by the mean sampled depth during a deployment.
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
2020-01-30T12:47:52