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Metadata: 2019-2020 Cornwall Inshore Fisheries and Conservation Authority (IFCA) Scallop dredging Survey
Abstract:
Cornwall Inshore Fisheries and Conservation Authority (CIFCA) is the authority responsible for the sustainable management of sea fisheries in the Cornwall IFCA district, which extends to 6 nautical miles from coastal baselines. Dredging for king scallops in the Cornwall IFCA district is currently subject to a number of byelaws, including; Shellfish Boats Byelaw, Scallop Dredge (Limited Fishing Time) byelaw and Methods of Fishing (Dredges) byelaw. These byelaws limit boat size to 16.46m in the district, prohibit scallop dredging between 7pm and 7am and stipulate gear requirements, including a limit of 12 dredges per vessel at any one time. Cornwall IFCAâ??s research team are preparing to start annual dredge tow surveys for scallops within the district. Currently the proposal is to conduct annual survey tows at a number of inshore sites within the district which were previously regularly surveyed by CEFAS along with some new sites. Data from these surveys, in conjunction with the larger current Cefas Stock Assessment program, would help to guide management of this fishery in inshore waters. Cornwall IFCA carried out this survey in preparation to start annual dredge tow surveys for scallops within the district. Currently the proposal is to conduct annual survey tows at a number of inshore sites within the district which were previously regularly surveyed by CEFAS along with some new sites. Data from these surveys, in conjunction with the larger current Cefas Stock Assessment program, would help to guide management of this fishery in inshore waters. The aim of the project was to develop a suitable method for repeat surveying for scallops from R/V Tiger Lily, to be used in multiple locations. The objectives of the survey were to trial the effectiveness of the N-Virodredge and tow bar for dredging for scallops from R/V Tiger Lily, to obtain measurement of all scallops (P. maximus) collect and to trial identifying and measuring the growth rings on individual scallop shells for ageing purposes. In 2019, five tows were completed with a total of 74 scallops recorded. In 2020, a total of nine tows were completed with a total of 105 scallops recorded.
Data holder:
Cornwall Inshore Fisheries and Conservation Authority
Click on the red button for resource contact details:
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Use constraints:
No restrictions to public access
| Other details | ||
| Internal code | Internally assigned metadata identifier | 3785 |
| Title | The title is used to provide a brief and precise description of the dataset such as 'Date', 'Originating organisation/programme', 'Location' and 'Type of survey'. All acronyms and abbreviations should be reproduced in full. | 2019-2020 Cornwall Inshore Fisheries and Conservation Authority (IFCA) Scallop dredging Survey |
| File Identifier | The File Identifier is a code, preferably a GUID, that is globally unique and remains with the same metadata record even if the record is edited or transferred between portals or tools. | fc5f58fca24ea6b70f2cb425c7fb26a2 |
| Resource Identifier | This is the code assigned by the data owner. | 2019-20_CIFCA_POR_DRE_SCA |
| Resource type | The resource type will likely be a dataset but could also be a series (collection of datasets with a common specification) or a service. | dataset |
| Start date | This describes the date the resource starts. This may only be the year if month and day are not known | 2019-02-28 |
| End date | This describes the date the resource ends. This may only be the year if month and day are not known | 2020-05-27 |
| Vertical extent (min) | A positive or negative decimal number, for example, the shallowest depth recorded if subtidal, or, if intertidal, the lowest point recorded. | 19.6000 |
| Vertical extent (max) | A positive or negative decimal number, for example, the deepest depth recorded if subtidal, or, if intertidal, the highest point recorded. | 34.2000 |
| Vertical extent reference | This descibes the vertical coordinate reference system as referred to in the EPSG register of geodetic parameters. (epsg-registry.org) | urn:ogc:def:crs:EPSG::5861 |
| Spatial resolution | This describes the spatial resolution of the dataset or the spatial limitations of the service. | inapplicable |
| Frequency of updates | This describes the frequency with which the resource is modified or updated i.e. a monitoring programme that samples once per year has a frequency that is described as 'annually'. | asNeeded |
| Abstract | The abstract provides a clear and brief statement of the content of the resource. | Cornwall Inshore Fisheries and Conservation Authority (CIFCA) is the authority responsible for the sustainable management of sea fisheries in the Cornwall IFCA district, which extends to 6 nautical miles from coastal baselines. Dredging for king scallops in the Cornwall IFCA district is currently subject to a number of byelaws, including; Shellfish Boats Byelaw, Scallop Dredge (Limited Fishing Time) byelaw and Methods of Fishing (Dredges) byelaw. These byelaws limit boat size to 16.46m in the district, prohibit scallop dredging between 7pm and 7am and stipulate gear requirements, including a limit of 12 dredges per vessel at any one time. Cornwall IFCAâ??s research team are preparing to start annual dredge tow surveys for scallops within the district. Currently the proposal is to conduct annual survey tows at a number of inshore sites within the district which were previously regularly surveyed by CEFAS along with some new sites. Data from these surveys, in conjunction with the larger current Cefas Stock Assessment program, would help to guide management of this fishery in inshore waters. Cornwall IFCA carried out this survey in preparation to start annual dredge tow surveys for scallops within the district. Currently the proposal is to conduct annual survey tows at a number of inshore sites within the district which were previously regularly surveyed by CEFAS along with some new sites. Data from these surveys, in conjunction with the larger current Cefas Stock Assessment program, would help to guide management of this fishery in inshore waters. The aim of the project was to develop a suitable method for repeat surveying for scallops from R/V Tiger Lily, to be used in multiple locations. The objectives of the survey were to trial the effectiveness of the N-Virodredge and tow bar for dredging for scallops from R/V Tiger Lily, to obtain measurement of all scallops (P. maximus) collect and to trial identifying and measuring the growth rings on individual scallop shells for ageing purposes. In 2019, five tows were completed with a total of 74 scallops recorded. In 2020, a total of nine tows were completed with a total of 105 scallops recorded. |
| Lineage | Lineage includes the background information, history of the sources of data, data quality statements and methods. | A single N-VirodredgeTM mounted on a custom designed tow bar was used during the survey. The N-Virodredge has the same width as a traditional scallop dredge (76cm), but uses individually mounted spring loaded tines, as opposed to a steel tooth bar to penetrate the sea bed. A shackle was used to connect the N-Virodredge to a central towing point on the custom made 1.8m tow bar. The winch on Tiger Lilyâ??s A-Frame (Spencer Carter 0.5t) was used to deploy and recover the dredge. Dyneema cable from the winch was used for towing. The slave hauler on the starboard side of Tiger Lily was rigged around the front of the vessel to the davit in the port quarter position. This hauler was used to raise and lower the end of the dredge bag for emptying the contents on to the deck. GPS track data was recorded in Hypack®MAX for the duration of the survey and all targets / waypoints created in Hypack. All positions in Hypack are sourced from the dedicated survey GPS (Furuno GP-32) on board and times in Coordinated Universal Time (UTC) are taken from the same source. Vernier stainless steel callipers were used for all shellfish measuring on board. The N-Virodredge was deployed through the A-Frame at the stern of Tiger Lily, using the onboard winch, whilst the vessel motored slowly forwards. Once the dredge was clear of the deck and at the surface of the water winching was halted. A lowered towing point was then created by attaching a chain with a connected towing block across the bottom of the A-Frame. The Dyneema cable was then run through this lowered towing point. The winch was then used to lower the dredge onto the seabed. The length of Dyneema cable out varied slightly (70-95m) with each tow, but was approximately three times the water depth. Once the dredge was on the seabed a start-of-line (SOL) position was created in Hypack. R/V Tiger Lily motored forward at a speed of 2-3 knots for the duration of the tows. The first two tows were considered trial tows and not of a set length. The remaining three tows were a nautical mile in length and considered three replicates, with tows 3 and 5 running in the same direction and tow 4 running in the opposite direction. Once tows were completed an end-of-line (EOL) mark was created in Hypack. The winch was then used to recover the dredge to the stern of the vessel. The lowered towing point was removed, before the winch was used to recover the dredge and tow bar onto the deck. The tow bar wheels were chocked with wood to secure the equipment. A line from the slave hauler, run through the port quarter davit was then connected to the rear of the dredge bag. The hauler was used to raise the end of the dredge bag and empty the contents on to deck. Before any catch sorting the slave hauler was used to lower the dredge bag back onto deck and the winch then used to move the dredge and tow bar into the water at the stern of the vessel. The catch from each tow was photographed, before the scallops were sorted into a fish box. The height of all scallops was measured from the umbo to the mantle and a width measurement was taken across the widest point, all to the nearest mm. Scientific Officers then trialled recording the length of each growth ring from the umbo of the scallop. These rings each represent a yearâ??s growth and can be used to age the scallops. The flat valve was used to determine growth rings, with lines on the curved valve used to confirm any uncertainties. Where rings were difficult to distinguish on the scallops a â??low confidenceâ?? mark was noted with the measurements. Scallop measurement data was entered in situ into a recording sheet which was set up in Microsoft Excel. At the end of the survey this spreadsheet was transported back to the office via a hard drive and stored on the Cornwall IFCA servers. All photographs taken as part of the survey were again transferred to Cornwall IFCAâ??s servers and stored in the same folder as the data, labelled with the survey title and date. At the end of the survey all track and target data was exported from Hypack in a .txt file format and stored on the Cornwall IFCA servers. The GPS tracks of all tows were plotted in MapInfo Pro v17.0 over hydrographic charts and side-scan sonar data of Veryan Bay. Microsoft Excel was used to plot charts of scallop height, width and age class. |
| Related keywords | ||
| Keyword | General subject area(s) associated with the resource, uses multiple controlled vocabularies | Marine Environmental Data and Information Network |
| General subject area(s) associated with the resource, uses multiple controlled vocabularies | NDGO0005 | |
| Keyword title | data.gov.uk | |
| Keyword | General subject area(s) associated with the resource, uses multiple controlled vocabularies | Species distribution |
| General subject area(s) associated with the resource, uses multiple controlled vocabularies | Fish and shellfish catch statistics | |
| General subject area(s) associated with the resource, uses multiple controlled vocabularies | Shellfish abundance and biomass in water bodies | |
| General subject area(s) associated with the resource, uses multiple controlled vocabularies | Shellfish morphology, age and physiology | |
| Geographical coverage | ||
| North | The northern-most limit of the data resource in decimal degrees | 50.2182 |
| East | The eastern-most limit of the data resource in decimal degrees | -4.8699 |
| South | The southern-most limit of the data resource in decimal degrees | 50.1987 |
| West | The western-most limit of the data resource in decimal degrees | -4.8858 |
| Regional sea | Western Channel and Celtic Sea | |
| 29E5 | ||
| English Channel | ||
| water column | ||
| Responsible organisations | ||
| Role | The point of contact is person or organisation with responsibility for the creation and maintenance of the metadata for the resource. | pointOfContact |
| Organisation name | Cornwall Inshore Fisheries and Conservation Authority | |
| Position name | Data Officer Cornwall IFCA Research Team | |
| enquiries@cornwall-ifca.gov.uk | ||
| Role | The distributor is the person or organisation that distributes the resource. | distributor |
| Organisation name | Cornwall Inshore Fisheries and Conservation Authority | |
| Individual name | Research Team Cornwall IFCA | |
| enquiries@cornwall-ifca.gov.uk | ||
| Role | The originator is the person or organisation who created, collected or produced the resource. | originator |
| Organisation name | Cornwall Inshore Fisheries and Conservation Authority | |
| Individual name | Research Team Cornwall IFCA | |
| enquiries@cornwall-ifca.gov.uk | ||
| Role | The custodian is the person or organisation that accepts responsibility for the resource and ensures appropriate care and maintenance. If a dataset has been lodged with a Data Archive Centre for maintenance then this organisation is be entered here. | custodian |
| Organisation name | Cornwall Inshore Fisheries and Conservation Authority | |
| Individual name | Research Team Cornwall IFCA | |
| enquiries@cornwall-ifca.gov.uk | ||
| Dataset constraints | ||
| 20 Limitations on Public Access - Access constraints | otherRestrictions | |
| 20 Limitations on Public Access - Other constraints | This states any limitations on access to the data and uses free text. | No restrictions to public access |
| 21 Conditions for Access and Use - Use limitation | This states any constraints on use of the data. Multiple conditions can be recorded for different parts of the data resource. If no conditions apply, then `No condtions apply` is recorded. This uses free text. | Data is freely available for research or commercial use providing that the originators are acknowledged in any publications produced. Permission must be sought if the data will be reproduced in full or part or if used in any analyses. This data is not suitable for use in navigation |
| Version info | ||
| Date of publication | The publication date of the resource or if previously unpublished the date that the resource was made publicly available via the MEDIN network. | 2021-05-27 |
| Harvest date | The date which this record has been (re)harvested from the provider. | 2026-04-19 |
| Metadata date | The date when the content of this metadata record was last updated. | 2024-07-22 |
| Metadata standard name | The name of the metadata standard used to create this metadata | MEDIN Discovery metadata standard |
| Metadata standard version | The version of the MEDIN Discovery Metadata Standard used to create the metadata record | 2.3.8 |