Annex 1: Methodology
Scottish Sea Fisheries Statistics are obtained by data extractions from FIN (Fisheries Information Network) administrative data, and IFISH, the UK data warehouse. IFISH provides information on sea fishing activity, catches and sales whilst FIN is used for vessel information in this publication.
Voyage and landings information is supplied by skippers. Vessels over 10 metres, are required by EU legislation to maintain logbooks or e-logbooks and provide landings declarations (see Glossary). For UK vessels over 15m in length, by law, this information must be recorded electronically in an e-logbook. In 2013, this system will be rolled out to all UK vessels over 12m. Vessels between 10m and 12m, and those between 12m to 15m who have not yet switched to e-logbooks, currently maintain the traditional paper logbook. The information from paper log books is input into FIN by hand by Marine Scotland Compliance Port Office staff, whilst the information from e-logs is processed and checked electronically before being imported into FIN. EU legislation does not require vessels of 10 metres and under to provide this information but in Scotland, these vessels provide equivalent information on NEP1 and SHELL1 paper returns.
Data on first sales of fish, which provides information on the value of landings, is provided by fish buyers and sellers under EU legislation on the Register of Buyers and Sellers (see Glossary). The information submitted forms the basis for reports to the Commission to meet the obligations of the EU legislation. The relevant legislation is listed in the Statistical Plan for Sea Fisheries statistics - see link below:
For four of the tables in the Statistical Bulletin, information from FIN/ IFISH is supplemented by information obtained through a fishermen employment survey distributed to port offices in each of the 18 Scottish fishing districts. The burden on respondents for this small survey is estimated to total no more than £1,000 per year, based on information obtained from each office on the time taken to complete the return and the grades of staff involved. In two of the tables, this information is compared to information on the labour force obtained from the Labour Force Survey.
Uses made of the statistics
Collection of information on sea fisheries is needed to produce reports for the EU Commission to meet the obligations of EU legislation. Internal users mainly require the underlying management information to monitor aspects of sea fishing, such as quota and effort uptake. The main use made of the published statistics is by external users, such as the Fish Producer Organisations.
The main macro-level use for the statistics is the assessment of the value of sea fishing to Scotland or specific sea areas. There is also a degree of political and media interest in the trends in the numbers of fishing vessels and numbers of fishermen employed. Scottish Parliament researchers use the information in briefings prepared on fisheries for MSPs and the Rural Affairs and Environment Committee. The published statistics are also used in the construction of the Scotland Performs Marine Environment Indicator -
The major micro-level use made by external users requesting specific data is to examine sea fishing activity in small areas of the sea around Scotland. Often as input to environmental impact assessments for off-shore energy developments.
The information in the administrative data bases are subject to extensive checking before it is enters the database. These checks are supplemented by quality assurance work performed by the Data Team throughout the year. This ensures consistency between the two vessel file administrative data bases and checks for missing returns of landing declarations. Furthermore, stakeholders can make requests to get data corrected/investigated if they assess that it does not correctly reflect their catch of quota stocks or usage of days at sea.
The main issue for the quality of the published statistics is the completeness of the information in the administrative systems. Information on catches of fish species not subject to quota or fish landed abroad can often take months for the information to be entered into the relevant administrative data base. It is for this reason that provisional statistics are not published until about 3-4 months after the year to which they relate, and the final statistics are published a further 4-5 months later. We assess that 0.2% of landings (by value) of Scottish vessels are omitted from the final published statistics each year due to delays in receipt of information on landings out with the UK. However, this small incompleteness does not affect the trends shown by the statistics. Although the provisional figures are not published until coverage of quota stocks is reasonably complete, information on non-quota stocks are less complete. The table below summarises the change between the provisional and final statistics by species type for landings of Scottish vessels. (Shellfish species other than Nephrops are not subject to quota.)
Increase in recorded landings by Scottish vessels since provisional statistics
|2012 Provisional Statistics
|2012 Statistical Bulletin
Value of landings information is derived from the Sales Notes which are submitted by UK vessels landing into EU countries, in line with the Buyers and Sellers legislation of 2005. This information is matched with the landing declaration for the values obtained for that landing. In instances where there is no Sales Note, for example when a UK vessel lands into a non- EU country, the value of the landing is estimated by using the average price obtained for the species in the previous quarter that the landing declaration was submitted.
One issue that concerns the quality of the statistics is that the statistics can only reflect the information supplied by the fishermen on their activity and catch. The automatic checking carried out on the data at the input stage, only checks for internal consistency of the information supplied. The introduction of the Buyers and Sellers legislation provides an external check on the declared landings of fish and undeclared ("black") landings have been assessed by Marine Scotland Compliance as being at negligible. For vessels with a length of 15 metres and over, the Vessel Monitoring System ( VMS) provides a check on the location of fishing activity recorded in fishermen's log books. Further checks are performed regularly by Marine Scotland Compliance to ensure enforcement of legalisation. However, despite these checks, there could be inaccuracies in the information submitted.
Revisions to the published statistics
The statistics for previous years published in the Statistical Bulletin are not amended for small changes (in the order of 0.2%) due to late data entry/amendment, as these do not affect the main trends presented. On the rare occasions that such revisions are required due to the discovery of errors in the previously published figures which affect the main trends presented, the revised figures are marked "(r)" and suitably footnoted to explain the reason for the revision. However, the statistics are revised between the published provisional statistics and those published in the Statistical Bulletin - see above. However, provisional statistics are always explicitly identified as such.
The formats of the tables presented in this Statistical Bulletin have been extensively revised, following a review of the Bulletin in 2009. Although figures for years before 2010 were derived from essentially the same data sources, there are a handful of cases where the figures do not agree exactly with those previously published. The differences are insignificant, with differences in the order of magnitude of tens between figures of the orders of tens or hundreds of thousands. These differences did not have any bearing on the trends or the statistics' fitness for purpose. These figures are consequently not described as revised.
Comparability with other UK countries
EU legislations cover information requirements for vessels over 10 metres and for all buyers and sellers, which results in the information derived from EU country data providers being comparable for all countries within the UK, as it is for all EU countries. The only difference between information collated in Scotland and that collated in the rest of the UK is that, through the NEP1 and SHELL1 returns, Scotland obtains equivalent information on a full coverage basis for vessels of 10 metres and under. In the rest of the UK, this information is provided on a sample basis only. However, the vast majority of fish are caught by vessels over 10 metres, so the information is effectively comparable for all UK countries, in spite of the difference in information capture for the 10 metre and under vessels.
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