CEFAScdfa14e9-4509-4e81-a30e-ebe06a998113 English dataset Centre for Environment, Fisheries and Aquaculture Science, Lowestoft Laboratory (CEFAS) Cefas Lowestoft Laboratory Pakefield Road Lowestoft Suffolk NR33 0HT UK data.manager@cefas.co.uk pointOfContact 2019-10-29T10:09:34 EPSG Geodetic Parameter Registry 2022-01-07 revision WGS 84 Northern North Sea Saithe (and Cod) Survey 2008/09 - Fisheries Science Partnership FSP Northern North Sea Saithe 2016-11-14 publication 2019-10-29 revision 2016-11-10 creation CEFAS18215 https://data.cefas.co.uk A programme set up in 2007/2008 which described the fine scale distribution and abundance in time and space of saithe (primarily) and cod, including specific information on the 2005 and 2006 year-classes of saithe, and the 2006 and 2007 year-classes of cod. Centre for Environment, Fisheries and Aquaculture Science, Lowestoft Laboratory (CEFAS) Cefas Lowestoft Laboratory Pakefield Road Lowestoft Suffolk NR33 0HT UK data.manager@cefas.co.uk originator Centre for Environment, Fisheries and Aquaculture Science, Lowestoft Laboratory (CEFAS) Cefas Lowestoft Laboratory Pakefield Road Lowestoft Suffolk NR33 0HT UK data.manager@cefas.co.uk custodian Centre for Environment, Fisheries and Aquaculture Science, Lowestoft Laboratory (CEFAS) Cefas Lowestoft Laboratory Pakefield Road Lowestoft Suffolk NR33 0HT UK data.manager@cefas.co.uk distributor Centre for Environment, Fisheries and Aquaculture Science, Lowestoft Laboratory (CEFAS) data.manager@cefas.co.uk owner Department for Environment, Food and Rural Affairs (DEFRA) defra.helpline@defra.gov.uk owner notPlanned Fish Biota abundance, biomass and diversity SeaDataNet P03 parameter discovery vocabulary 2011-03-25 revision Species distribution GEMET - INSPIRE themes, version 1.0 2008-06-01 publication Water column SeaVoX Vertical Co-ordinate Coverages 2010-05-18 revision Marine Environmental Data and Information Network MEDIN metadata record availability 2012-01-11 publication data.gov.uk MEDIN metadata record availability 2012-01-11 publication otherRestrictions noLimitations otherRestrictions Adherance to the Cefas Data access policy required. Terms and conditions of OGL – Open Government Licence apply. `http://www.nationalarchives.gov.uk/doc/open-government-licence/`_ .. _`http://www.nationalarchives.gov.uk/doc/open-government-licence/`: http://www.nationalarchives.gov.uk/doc/open-government-licence/ English biota -5.00 9.00 57.00 62.00 2007-05-01 2009-03-30 Binary Unknown https://data.cefas.co.uk/view/18215 Cefas Data Portal download 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. dataset INSPIRE Data Specification on Species Distribution – Technical Guidelines 2013-12-10 publication false See the referenced specification Commission Regulation (EU) No 1089/2010 of 23 November 2010 implementing Directive 2007/2/EC of the European Parliament and of the Council as regards interoperability of spatial data sets and services 2010-12-08 publication true See the referenced specification Methods The fishing vessel and area fished The study was conducted between May 2007 and March 2009 (herein referred to as the study period) on board the commercial fishing vessel MFV “Farnella” (length overall, 40.2 m; GRT 667; main engine, 1880 kW). “Farnella” uses a trawl typical of the northern North Sea saithe fishery (headline height 4 m, door spread 110–115 m codend mesh >110 mm, tow speed 4 knots). Throughout, fishing took place in the northern North Sea, but for the most part focused on ICES Division IVa). Data collection Self sampling Estimating fish numbers and weights The skipper and crew were asked to provide estimates of the weight and number of retained and discarded cod and saithe of each size grade for every haul. At the end of each haul, fishroom staff provided the wheelhouse a tally recording the number of baskets per grade of cod and saithe caught. Baskets were estimated at 45 kg, and the numbers of fish in each basket were assessed regularly (to take into account the seasonal and spatial variations of fish condition). Biotic and abiotic measurements All cod were caught in every haul were measured, and a minimum of 100 saithe per size grade were measured per trip. When necessary (large hauls), saithe numbers were raised to haul level as a proportion of the total catch, using volume-based raising factors. All fish were measured to the nearest centimetre below (total length). Environmental conditions (sea state, wind strength/ direction) and physical conditions (depth, position, haul-duration and gear properties) were recorded along with the biological data. Observer sampling Three observer trips were conducted throughout the study period. The first observer trip, in May 2007, was used to train the skipper and crew of the “Farnella” in sampling methods. The second and third observer trips were used to maintain the standards applied from the start (there was skipper and crew turnover) and particularly to ensure that the self-sampling was of a very high standard. These second two observer trips were carried out in the first quarters of 2008 and 2009. Information collected from the trained observers was used to validate the data provided by the vessel and to provide a more detailed overview of the fishery with respect to bycatch and discards. Fish age determination A total of 29 000 fish otoliths was removed at sea by observers and from fish landed to fish markets. Of these, 15 500 were from cod and 13 500 from saithe. All otoliths were extracted from fish that had been caught in ICES area IVa between April 2007 and March 2009 (the study period covered by this report). Otoliths were mounted, sectioned, stained, read, and re-read for quality control purposes, according to the protocols of Cefas and Marine Scotland - Marine Laboratory. Data analysis Data handling Trip, haul, length, catch and age data were entered onto a MS access database. All data entered were cross-checked against the paperwork and quality-controlled for inaccuracies. Data were handled using SPSS V17 statistical software, charts were produced using Sigmaplot V10.0, and maps were created in MapInfo V7.8. Converting fish length into fish ages Age-at-length data collected from the 15 500 cod and 13 500 saithe that were aged were used. Data were collected throughout the year to take into account length variations of a growing age class. At a given length in any quarter, fish age will vary. For example, in quarter 3 of 2007, 49 cod of the 70-cm length class were aged as between one and four years old, so when one 70-cm cod was observed and measured in quarter 3, it was aged proportionally to what was observed in the population. Each fish length has a different combination of proportions at a given age. If more than one fish was observed at a given length, then the number at length was multiplied by the proportion at age to give the estimated numbers at a given age. Age-length keys (ALKs) applied to this analysis are area- (ICES IVa), species- (cod or saithe) and season-specific (quarters 1, 2, 3 and 4). Sex is not taken into account. When a fish length could not be matched with a length that had been aged in a particular quarter, then seasonality was removed and an aggregated ALK for the whole year was used. This occurred in <2% of the >75 000 fish measured. Generating an age-category key Haul data are presented in numbers of fish caught by category. In order to make use of this information and to evaluate the numbers-at-age of fish caught at a particular haul location, we need to understand the age spread of a particular category. Fishermen were asked to record the category of the fish measured. With each measurement we can assess the age of the fish, so an area, species and season age-category key can be generated. For example, in quarter 3 of 2007, an estimated 1 990 category 4 cod were caught. These were aged between 2 and 6 years old, so when a category 4 fish was caught (now disregarding length information) we applied the same method as an ALK and aged it proportionally using an age category key (ACK). For example, If 1000 category 4 cod were caught in a particular haul, we would estimate 533 to be age 2 (1000 x 0.533), 398 to be age 3 (1000 x 0.398), 66 to be age 4, etc. Calculating catch per unit effort The total numbers of fish caught each month (by species) were divided by the total haul duration to determine the numbers of fish caught per hour, or the catch per unit effort (CPUE). This unit allowed the catch data to be standardised and used for comparative analysis. Summary The Northern North Sea Saithe (and Cod) FSP was established in response to an industry- and science-perceived absence of realistic data on the 2004 and 2005 year classes of saithe and the 2005 and 2006 year classes of cod. The 2005 and 2004 year classes of saithe (4 and 5 year olds) are of particular interest because they were predicted to contribute significantly to projected landings in 2008 and subsequently to contribute to the spawning-stock biomass of the species in 2009. This study uses data collected at haul level by fishermen aboard the commercial fishing vessel MFV “Farnella” over a two-year period. Throughout, fishing was widespread in the northern North Sea, but for the most part was focused on ICES Division IVa. The skipper and crew were trained in sampling techniques prior to collecting the data. and all information sent ashore was checked regularly. Observer-accompanied trips were also carried out to ensure a high standard of data quality. Between May 2007 and March 2009 (the study period) MFV “Farnella” embarked on 51 commercial fishing trips in the northern North Sea (ICES IVa), hauled 1154 times, and caught 3.3 million saithe (Pollachius virens) and 51 000 Atlantic cod (Gadus morhua). Of the fish caught, the crew measured most of the cod (48 772) and 26 518 saithe (75 290 in total). MEDIN 3.1.1