IMIS - Marine Research Groups

Purpose of data capture: The purpose for which the records were collected was to identify the national distribution of Twaite Shad (Alosa fallax) in Scotland. Most records were obtained as part of sea fishing bycatch which were and reported. Methods of data capture: Records were included into the dataset after literature review or direct observations revealed presence. Methods included stake nets, stake net and traps, single trap bag nets, net and cobble, seine netting, purse seine netting, ring netting, fixed engine and trawler data. Geographical coverage: The geographical extent of the Twaite Shad dataset is limited to the East and West coasts of Scotland, particularly the Solway Firth and the North Sea. The survey reviewed known records of Twaite shad distribution nationally. Data was also obtained via the Galloway Fisheries Trusts rare fish project. Records from both these sources were mainly in rural coastal areas of Scotland. However, data from Marine Scotland Rare Fish Database (G. Henderson, pers comm) also revealed sea fishery data from vessels in the North Sea. All of the Marine Scotland Rare Fish Database records are collated using six figure British national grid-references. The majority of the remaining data was collated using a resolution of 100m grid-references. Temporal coverage: This dataset was created using a literature review of Twaite Shad research and catch data in Scotland; as such various records from various sources over a number of years have been used. Changes in level of fishery bycatch reporting, recording activity over time and changes in data source vary (e.g. changes with the seasons, literature and sea fishery surveys). There are 34 records from 1951 to 2008 where date is recorded by year and 346 records from 1927 to 2010 where records have an exact date. The records within the dataset have been documented all year round. Data quality: The Clyde River Foundation has reviewed all known literature on Alosa fallax within Scotland and the UK, collaborated with other fishery trusts, Marine Scotland and referred to national databases (NBN Gateway) to ensure that the dataset has a geographically comprehensive coverage. However the data have only been updated and maintained sporadically with only a few fish being encountered annually and not by any one definitive person or organisation.