2003 - Ongoing, EIFCA, (Eastern Inshore Fisheries and Conservation Authority), The Wash, Mussel Survey
Mussel surveys are carried out once a year during Autumn/Winter. Data is collected for stock assessments to inform fisheries management (opening times, Total Allowable Catch, which cockle beds to open, which fishery to open) as per the Wash Fishery Order fihseries managed by the IFCA. Data also forms part of the Appropriate Assessment process required to open a fishery under Regulation 61 of The Conservation of Habitats and Species Regulations 2010 (SI No. 2010/490), regarding The Wash and North Norfolk Coast Special Area of Conservation (Habitats Directive), The Wash Special Protected Area (Birds directive), the Wash Ramsar and SSSIs. Abundance and weight by year-class and width is recorded from several sites within around 20 mussel beds in The Wash. Data is initially recorded by hand then is input into MapInfo to make density charts; data is then exported into Excel tables for reference. Surveys are conducted by day-grabs were access is available however foot surveys are conducted at some sites.
dataset
http://www.eastern-ifca.gov.uk/index.php?option=com_content&view=article&id=15&Itemid=30
name: Research report 2011
EIFCA000002
http://www.eastern-ifca.gov.uk/
eng
urn:ogc:def:crs:EPSG::4326
biota
revision
2008-01-06
revision
2009-11-16
0.0385
0.6262
53.1567
52.7862
creation
2009-06-18
Southern North Sea
revision
2010-01-01
benthic boundary layer
2003-01-01
2016-11-01
publication
2012-04-18
annually
Altough the surveys have been conducted prior to 2003, survey methodology changed to the current methods in that year. Data from previous years is not currently digitised. No end date was given as the survey is ongoing. The publish date for the 2011 research reoprt relates to when the report was placed on the EIFCAs website. The perimeter of each bed was defined by walking around the bed at low water and entering waypoints into a portable GPS unit. These waypoints were transferred to a Geographic Information System (GIS), MapInfo, from which the perimeter of each bed was plotted, allowing an estimation of their area to be made. Transect surveys were conducted across the bed to ascertain the coverage and density of mussel. Transects were chosen that would attain the most even coverage of the bed that the low water period and the extent of the bed would allow. The route of transects across the bed were recorded by entering waypoints into the GPS unit and later plotting them in MapInfo. As transects were walked across the bed, the coverage of mussels was determined using an 11cm ring attached to a pole. Every three paces the ring was placed down on the mussel bed and the resence (hit) or absence (miss) of mussels within the ring recorded. Randomisation was achieved by placing the ring down to one side, outside of the field of vision of the user. Mussel samples, used to determine the biomass of the mussels on the bed, were collected from those contained within the rings. Depending on the length of the track and the mussel density, it was decided in advance if all hits were to be sampled, or whether a lower proportion could be used to provide a total sample large enough to determine the average density and size frequency of the population. In the case of these surveys a sampling frequency of between once every second hit and once every seventh hit was used. Samples taken from the rings were collected in a container. Every 450 paces, after 150 hit/miss determinations had been conducted, the samples were washed using a 0.5mm sieve and placed in labelled bags. On returning to the research vessel the live mussels were separated from the debris in each sample. The length of each mussel was determined, and the samples divided into those mussels that were of marketable size (>45mm) and those that were smaller. The weights of these samples were then recorded. During this years surveys, the number and weight of mussels >25mm length were also recorded as this size range is favoured by oystercatchers. The coverage, density and area of the mussel bed were multiplied together to estimate the biomass of mussels on the bed. Size distributions were obtained from the length measurements of mussel in the retained samples.
Data is freely available for research or commercial use providing that the originators are acknowledged in any publications produced, charts are not to be used for navigation.
No restriction to public access
Senior Research Officer
Eastern Inshore Fisheries and Conservation Authority
originator
MEO Data Lead
Eastern Inshore Fisheries and Conservation Authority
custodian
MEO Data Lead
Eastern Inshore Fisheries and Conservation Authority
pointOfContact
2016-11-15