The English 3rd Quarter North Sea Groundfish Survey

Area

ICES Sub-area IV. North Sea.

Objectives

The English ground fish survey has the primary objectives to obtain information on:

• The distribution, size composition and abundance of all fish, commercial shellfish and cephalopod species.
• The age-length distribution of selected species for ICES WG input and biological studies.
• Biological parameters of selected commercial species.

Secondary objectives are to collect data regarding the benthic, sedimentary and hydrographic environments, and to collect biological data in support of Cefas projects.

History

The English ground fish survey of the North Sea began in 1977, and is carried out during August/September of each year.  Data collected on the survey has been used in the assessment of North sea stocks of cod (Gadus morhua), haddock (Melanogrammus aeglefinus), whiting (Merlangius merlangus), saithe (Pollachius virens), Norway pout (Trisopteris esmarkii), herring (Clupea harengus) mackerel (Scomber scombrus), sprat (sprattus sprattus) and plaice (Pleuronectes platessa).  The duration of the survey is between 4 - 5 weeks and extends over the whole North Sea within the 200m depth contour. Since 1991, the survey has formed part of the International Bottom Trawl Survey series, which is coordinated by the International Council for the Exploration of the Sea  (ICES).

The vessel and the gear

The vessel used for all the survey work up to 2002 was RV Cirolana. Since 2003, the survey has been conducted from RV Cefas Endeavour.  The survey has used 2 types of otter trawl over the last 22 years, the Granton Trawl and the Grande Ouverture Verticale (GOV). The Granton trawl was used up until 1991 but was then superceded by the GOV from 1992.  These trawls are both otter trawls though the GOV is considerably larger in size and volume.   In the latter years the geometry of the gear has been measured by use of SCANMAR equipment. Both gears are bottom trawls and are designed to catch fish living on or near the seabed.

Operation of the survey

The same station positions are worked each year. This combined with the use of a standard rigged gear makes the data from each year directly comparable with that of other years. 

The catch is sampled by the staff onboard to provide total catch weight and length distributions for all species caught. All the information is collected using the Cefas Electronic Data Capture system (EDC). Otoliths are taken to provide fishery independent estimates of the age composition of the stock.

Results

Current survey results can be mapped by ICES rectangle from iSEA - interactive Spatial Explorer and Administrator or full international data can be found on ICES Fishmap.