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1999 University Marine Biological Station, Millport, Marine observatory of the European University Institute of the Sea, ICRAM, Chioggia, Fisheries Research Services, Aberdeen Marine Laboratory Clyde Sea Toothed Dredge Survey An 18-month REEFS research project was undertaken to investigate the three main types of toothed dredge gear used for scallop (Pecten, Aequipecten spp.) fishing in Europe. Field investigations were carried out to assess the ecological impact of scallop dredging and experimental fishing studies were performed. The three scallop grounds which were investigated during the study were: Northern Adriatic (Italy); the Bay of Brest (North-Western France); and the Clyde Sea area (West coast of Scotland), which were paired sites. The study compared the effects of different types of toothed dredges on scallop grounds. Rapido trawls were used on the sandy bottom encountered in the Adriatic scallop fishing grounds. Brenton dredges were used in the French scallop grounds and Scottish grounds used the Newhaven trawl. Both scallop grounds were maerl based. The lighter weight rapido trawl penetrates surface sediment to 2cm to dislodge scallops and flat fish in the surface of the sea bed. Both the Brenton and Newhaven trawls penetrated the sediment surface down to 10cm. They are designed to be heavier to cope with more difficult fishing grounds. Toothed dredging field manipulation experiments identified the major ecological impacts of scallop fishing. The study established that toothed dredging had an impact on the sediment surface physical features, re-suspended silt fractions and disrupted sessile epifauna and habitat characterization. Dredging tracks were littered with dead or damaged organisms which attracted scavengers. Dredging tracks can be visible for a period of months to years. Areas with highly mobile sediment characterization were able to erase the effects of dredging faster than areas of sheltered mud or maerl. Experimental impact assessments were performed to determine the effects of dredging on surface living and sessile organisms. The experiments were conducted on sites in the Adriatic, France, and Scotland where commercial fishing was not possible. Bottom samples (up to 60cm below the sea bed) were taken via suction-lift techniques. Water lifts were used in the Adriatic site while air lifts were used in the French and Scottish sites. Sampling was also conducted using grabs. The investigations revealed that organisms living in the surface layer of the sea bed are disturbed by the process of dredging, however organisms are small enough to deter damage and survive. Deep burrowing organisms, large and long-lived species, are protected from toothed dredges (as adults). Large, sessile epifauna are the organisms which suffer the most impact of dredging and form the bulk of by-catch. Damaged organisms and discards of dredging are exploited by scavenging organisms. Toothed dredges are renowned to be the most environmentally damaging of the fishing gear which is towed in European waters. The project has established that toothed dredges affect the same sea bed area differently and therefore impacts the ecology of the substrata differently.
Data Archive for Seabed Species and Habitats (DASSH)
DASSH terms and conditions apply (https://www.dassh.ac.uk/terms-and-conditions)
Other details | ||
Internal code | Internally assigned metadata identifier | 3651 |
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. | 1999 UMBSM/ IUEM/ ICRAM/ MLA Clyde Sea Toothed Dredge Impact Survey - Grab and Suction Sampling |
Alternative title | The purpose of alternative title is to record any additional names by which the dataset may be known. | 1999 University Marine Biological Station Millport (UMBSM) Study Contract Clyde Sea Toothed Dredge Survey, 1999 UMBSM/ IUEM/ ICRAM/ MLA Clyde Sea Toothed Dredge 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. | 69da2e3f24741fdba75e2173bcb081b5 |
Resource Identifier | This is the code assigned by the data owner. | DASSH-116 |
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 | 1999-06-07 |
End date | This describes the date the resource ends. This may only be the year if month and day are not known | 1999-06-07 |
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'. | notPlanned |
Abstract | The abstract provides a clear and brief statement of the content of the resource. | 1999 University Marine Biological Station, Millport, Marine observatory of the European University Institute of the Sea, ICRAM, Chioggia, Fisheries Research Services, Aberdeen Marine Laboratory Clyde Sea Toothed Dredge Survey An 18-month REEFS research project was undertaken to investigate the three main types of toothed dredge gear used for scallop (Pecten, Aequipecten spp.) fishing in Europe. Field investigations were carried out to assess the ecological impact of scallop dredging and experimental fishing studies were performed. The three scallop grounds which were investigated during the study were: Northern Adriatic (Italy); the Bay of Brest (North-Western France); and the Clyde Sea area (West coast of Scotland), which were paired sites. The study compared the effects of different types of toothed dredges on scallop grounds. Rapido trawls were used on the sandy bottom encountered in the Adriatic scallop fishing grounds. Brenton dredges were used in the French scallop grounds and Scottish grounds used the Newhaven trawl. Both scallop grounds were maerl based. The lighter weight rapido trawl penetrates surface sediment to 2cm to dislodge scallops and flat fish in the surface of the sea bed. Both the Brenton and Newhaven trawls penetrated the sediment surface down to 10cm. They are designed to be heavier to cope with more difficult fishing grounds. Toothed dredging field manipulation experiments identified the major ecological impacts of scallop fishing. The study established that toothed dredging had an impact on the sediment surface physical features, re-suspended silt fractions and disrupted sessile epifauna and habitat characterization. Dredging tracks were littered with dead or damaged organisms which attracted scavengers. Dredging tracks can be visible for a period of months to years. Areas with highly mobile sediment characterization were able to erase the effects of dredging faster than areas of sheltered mud or maerl. Experimental impact assessments were performed to determine the effects of dredging on surface living and sessile organisms. The experiments were conducted on sites in the Adriatic, France, and Scotland where commercial fishing was not possible. Bottom samples (up to 60cm below the sea bed) were taken via suction-lift techniques. Water lifts were used in the Adriatic site while air lifts were used in the French and Scottish sites. Sampling was also conducted using grabs. The investigations revealed that organisms living in the surface layer of the sea bed are disturbed by the process of dredging, however organisms are small enough to deter damage and survive. Deep burrowing organisms, large and long-lived species, are protected from toothed dredges (as adults). Large, sessile epifauna are the organisms which suffer the most impact of dredging and form the bulk of by-catch. Damaged organisms and discards of dredging are exploited by scavenging organisms. Toothed dredges are renowned to be the most environmentally damaging of the fishing gear which is towed in European waters. The project has established that toothed dredges affect the same sea bed area differently and therefore impacts the ecology of the substrata differently. |
Lineage | Lineage includes the background information, history of the sources of data, data quality statements and methods. | The research was carried out by members of the University Marine Biological Station Millport (UMBSM), the Institut Universitaire Europeen de la Mer (IUEM), the Instituto Centrale per la Ricerca scientifica e technologica Applicata al Mare (ICRAM) and the Fisheries Research Services, Marine Laboratory Aberdeen (MLA). The study has been carried out with the financial assistance of the European Commission. The report does not necessarily reflect the views of the European Commission. The study project is in support of the Common Fisheries Policy. The research programme was designated the title: "Research into the Environmental Effects of Fishing for Scallops". The acronym REEFS was assigned during a meeting of the partner institutions. The main purpose of the programme is to establish detailed comparative information on the effects of various fishing gear on valuable shared maritime resources, which can then be used to efficiently co-ordinate the management of global fisheries. All study sites were position fixed using DGPS. A side scan sonar (Model 260TH surface control unit, Model 272TD 'tow fish') was also used at the study area in the Adriatic. The sidescan sonar was used to accurately map the wreckage of the 'Quintino Sella' (unfished control site) and to locate rapido trawl tracks on the adjacent scallop fishing ground. Divers were used to establish the control site plot. In the french (Kongsberg-Simrad Model OE1360) and Italian (Telesub Laterna, Pozano Magra, Model PN 302.014) study sites, underwater television cameras (UWTV) were used to assess the epibenthic ecology and sea bed conditions of both the control and test sites. These methods were developed at UMBSM and adapted to film scallop dredges used in France and Italy. Within the Clyde Sea area, study sites were chosen that had previously been surveyed using RoxAnn (trade mark)(ROV) and divers. In addition, stills cameras (Nikonos V) were used to record the changes of benthic conditions. Experimental sites during the project were chosen as they were not commercially fished for scallops. Study sites were not commercially fished due to: its proximity to a wreck (Italy); the presence of an underwater communication cable (Scotland); and an agreement by fishers (France). At each site, between four and seven replicate ca 15 minute tows were performed. Gear rigging and towing speed reflected the common practices identified within each local fishing ground (5 knots in Italy; 2 knots in France and Scotland). The catch from each tow was hauled on-board and emptied onto the deck. The catch was sorted and collated into phylum categories and wet weighed. Pecten jacobaenus (Italy), P. maximus (France and Scotland) and Aequipecten opercularis were kept separate. The scallops were identified to species level, counted and assessed for dredge damage. Small macrobenthos were weighed and identified. Unidentifiable organisms were preserved (8% borax-buffered formalin in sea water) or frozen for later examination. Benthos suction samples (4mm mesh sieve) were obtained at all sites. Trials by UMBSM established the use of 0.5metre squared steel quadrats with 30 cm high walls as sufficient for suction sampling. Three replicate suction samples were obtained at 0-10, 10-30 and 30+ cm depth intervals, before and after experimental fishing investigations. In each region, investigations into deep-burrowing juvenile success and settlement were performed with the use of a 0.1metre squared grab sampler. Juvenile members were located in the surface layers of the sediment. Grabs were weighted with 30 kg of lead to ensure penetration to 8-10 cm of sediment. Samples were passed through a 1mm mesh sieve on deck and preserved in 8% borax-buffered solution of formalin seawater. Sorting of organisms preceded. The report describes each particular tow, suction and sampling methods which were adopted at each study site in full. Two study grounds (maerl) were established in the Clyde Sea area (10-12m below Chart Datum (CD)), which supported both UK commercial scallop species P. maximus and A. opercularis. Site 1, Stravanan Bay, has had a 40 year scallop fishing history in comparison to site 2 which had never been fished (trawling-prohibited area since 1968). Pre-fishing surveys were performed at each site during April-May 1999. The initial site surveys established that grounds were suitable for research trawling by locating obstructive debris. The presence of previous dredge tracks were recorded by divers and assessments of scallop densities, maerl coverage and conspecific species presence and abundance were performed using 1 meter squared quadrats. Each survey site was marked with a large floating buoy. Two plots (test and control) at site 1 were established within a 50x50 m square situated around the buoy marker. Test and control plots were situated either side of the marker. Sediment samples at site 1 were taken 2 days prior to fishing experiments. Fifteen Van Veen grab samples were also taken within the Plot area (8 in the control plot; 7 in the test plot). At site 2, three Newhaven scallop dredges were towed at a speed of 2-3.5 km per hour as is reflected by commercial scallop fishing vessels. The dredging of experimental plots was performed via RV Aora (UMBSM) and lasted for 15 minutes on each ground (total of four on each ground). Dredges were performed as close to buoy markers as possible. Catches from each tow were analysed and UWTV video footage (taken prior to trawl at site 1) was compared with footage obtained in Italy and France. Once dredging experiments were performed, post-fishing surveys of site 1 were carried out. The impacted area and damage caused (including fauna impacts) by dredging was recorded and photographed by divers within 1 hour of the trawl ceasing. Fishing gear efficiency was assessed by observing scallops left on the sea bed and compared to those which had been caught. Sediment samples were collected again two days after the fishing experiments. |
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 | Habitats and biotopes | |
General subject area(s) associated with the resource, uses multiple controlled vocabularies | Land cover | |
General subject area(s) associated with the resource, uses multiple controlled vocabularies | Oceanographic geographical features | |
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 | Fauna abundance per unit area of the bed | |
General subject area(s) associated with the resource, uses multiple controlled vocabularies | Fishing by-catch | |
General subject area(s) associated with the resource, uses multiple controlled vocabularies | Habitat characterisation | |
General subject area(s) associated with the resource, uses multiple controlled vocabularies | Sediment resuspension | |
General subject area(s) associated with the resource, uses multiple controlled vocabularies | Seabed photography | |
Geographical coverage | ||
North | The northern-most limit of the data resource in decimal degrees | 56.0613 |
East | The eastern-most limit of the data resource in decimal degrees | -4.9658 |
South | The southern-most limit of the data resource in decimal degrees | 55.7178 |
West | The western-most limit of the data resource in decimal degrees | -5.3641 |
Regional sea | Minches & Western Scotland | |
40E4 | ||
VIa | ||
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 | Data Archive for Seabed Species and Habitats (DASSH) | |
Position name | Data Manager | |
Phone | 01752 633102 | |
Fax | 01752 633291 | |
Delivery point | Marine Biological Association of the UK, The Laboratory, Citadel Hill | |
Postal code | PL1 2PB | |
City | Plymouth | |
Role | The distributor is the person or organisation that distributes the resource. | distributor |
Organisation name | Data Archive for Seabed Species and Habitats (DASSH) | |
Position name | Data Manager | |
Phone | 01752 633102 | |
Fax | 01752 633291 | |
Delivery point | Marine Biological Association of the UK, The Laboratory, Citadel Hill | |
Postal code | PL1 2PB | |
City | Plymouth | |
Role | The originator is the person or organisation who created, collected or produced the resource. | originator |
Organisation name | University Marine Biological Station (UMBS), Millport | |
Individual name | Philip Smith | |
Postal code | KA28 0EG | |
City | Millport | |
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 | Data Archive for Seabed Species and Habitats (DASSH) | |
Position name | Data Manager | |
Phone | 01752 633102 | |
Fax | 01752 633291 | |
Delivery point | Marine Biological Association of the UK, The Laboratory, Citadel Hill | |
Postal code | PL1 2PB | |
City | Plymouth | |
Resource locators | ||
Locator URL | Web address (URL) that links to the resource | http://doi.org/10.17031/648713bbb256d |
Locator name | Name of the web resource | DOI link |
Locator URL | Web address (URL) that links to the resource | http://www.dassh.ac.uk |
Locator name | Name of the web resource | DASSH website homepage |
Dataset constraints | ||
20 Limitations on Public Access - Access constraints | ISO restriction code chosen from ISO 19115-1 Codelist | otherRestrictions |
20 Limitations on Public Access – Other constraints | Any restriction on the use of the resource such as the need to agree to certain licence conditions. | DASSH terms and conditions apply (https://www.dassh.ac.uk/terms-and-conditions) |
21 Conditions for Access and Use - Use limitation | Any restrictions imposed on accessing the resource such as the need to agree to certain licence conditions. | The contents of this report may not be reproduced unless the source of the material is indicated. DASSH terms and conditions apply (https://www.dassh.ac.uk/terms-and-conditions) |
Available data formats | ||
Data format | Format in which digital data can be provided for transfer | Delimited |
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. | 2023-06-22 |
Date of last revision | The most recent date that the resource was revised. | 2023-06-22 |
Date of creation | The date that the resource was created. | 1999-06-07 |
Metadata date | The date when the content of this metadata record was last updated. | 2023-06-22 |
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 |
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