DFO Maritimes Research Vessel Trawl Surveys Fish Observations
Citation
Clark D, Hayden H, Fanning P, Smith S (2021). DFO Maritimes Research Vessel Trawl Surveys Fish Observations. Canadian node of the Ocean Biogeographic Information System (OBIS Canada). Metadata dataset https://doi.org/10.15468/hlhopd accessed via GBIF.org on 2024-09-26.Description
This page has been Archived. The new versions of the datasets can be found at: Maritimes Summer Research Vessel Surveys http://ipt.iobis.org/obiscanada/resource?r=maritimes_summer_rv_surveys Maritimes Spring Research Vessel Surveys http://ipt.iobis.org/obiscanada/resource?r=maritimes_spring_rv_surveys Maritimes Fall Research Vessel Surveys http://ipt.iobis.org/obiscanada/resource?r=maritimes_fall_rv_surveys Maritimes 4VSW Research Vessel Surveys http://ipt.iobis.org/obiscanada/resource?r=maritimes_4vsw_rv_surveys This is the OBIS-formatted view of the Canadian Department of Fisheries and Oceans (DFO) Maritimes Research Vessel Trawl Surveys. This data is created using a Structured Query Language (SQL) program run against the DFO production database. Refer to the project section for more information about the surveys. This OBIS product reports the abundance and weight of demersal fish species captured by a variety of trawl gear and vessels. Catch data appear in the "individualcount" and "observedweight" OBIS fields (DwC dynamic properties field)and have been normalised for distance towed. The swept area of each tow can be found in the "samplesize" field of the OBIS schema (DwC dynamic properties field). Care should be taken when using multiple types of gear since the catchability of different fish species varies from gear to gear. The OBIS field "locality" contains the DFO stratum number where each tow was conducted. The OBIS field "collectioncode" identifies which survey series each data record comes from. Strata statistics required to derive stratified random estimates of catch abundance and biomass can be found on the OBISCanada website http://obiscanada.marinebiodiversity.ca/database/dfo-maritimes-survey-strata-statistics).Sampling Description
Study Extent
Random stratified research survey conducted to monitor distribution and abundance of fish and invertebrates available to a bottom otter trawl at depths from 15 fm to 400 fm. d. (NAFO areas 4VsW) Data collected include total catch in numbers and weight by species, length frequency for all fish and selected invertebrates, ageing materials, individual specimen weight, sex and maturity stages, and additional specimen collections as requested (eg genetic material, stomach content data, specimens for museums and schools).Sampling
Purpose: To conduct research surveys of the Scotian Shelf to estimate the abundance of multi species. Special collections of stomachs, otoliths and gonads were also required. Other collections were also taken as per an investigators request.Quality Control
Data are input while at sea using the in-house developed application Groundfish Entry System. Rigorous error checks and warnings are applied and edits take place during sampling in most cases. Further quality assurance checks are applied before loading to the production database. Scientific names associated with resource occurrence records have been mapped to recognized standards - marine taxa have been mapped to the World Register of Marine Species (WoRMS). The WoRMS codes, the AphiaIDs have been included as LSIDs in the occurrence record DwC field scientificNameID.Method steps
- The original data records from research vessel surveys are housed in Canadian Ecosystem Survey Database in GROUNDFISH schema on SABS an Oracle production instance at St Andrews Biological Station. This database is accessible on the intranet to DFO staff only. A view of the database was created by OBIS Canada and queries were run to extract Darwin Core (DwC) records in the required IPT format. Criteria were added to produce two OBIS resources: one for fish and one for invertebrates (http://iobis.org/mapper/?resource_id=237,257). This dataset was first published on OBIS in 2007 and has since been refreshed on an annual basis. In 2015 the 9th version of this dataset was published to OBIS. Users should contact the data provider if they wish to access the source database.
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The dynamicProperties field in the DwC record contains information on the standardized samplesize (number of nautical miles * height of the gear - example 1.9 n.miles * 41.0 ft), observed weight in grams per sample and bottom temperature in degrees Celsius, if available. SQL script: dynamicProperties: 'samplesize=' & [samplesize] & IIf(Nz([observedweight],0)>0,('; weight=' & Format([OBSERVEDWEIGHT],'0.000') & 'Kg per sample')) & IIf([temperature] Is Not Null,('; Bottom Temperature(C)=' & [temperature]))
Those who regularly use this type of data would refer to the 'tow length' * 'wingspread' as the 'swept area'. The wingspread actually varies with each tow, but we don't have that information in a database, and only have it for some years. The tow also catches fish from outside the wingspread, since some fish are herded by the doors and tow cables. Some fish in the path of the trawl escape. The height of the headline varies, so the volume swept varies as well.
Sample size suggests we are sure of the area and we sampled everything that was there. It suggests a level of precision that is not realized by a bottom trawl, so a better term would have been "swept area". *NOTE n.miles = nautical miles - Advanced ad hoc queries: Strata statistics required to derive stratified random estimates of catch abundance and biomass can be found on the OBISCanada website. http://obiscanada.marinebiodiversity.ca/database/dfo-maritimes-survey-strata-statistics
Additional info
marine, harvested by iOBISTaxonomic Coverages
Groundfish - primarily fish and squid
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Actinopterygii
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Ascidiacea
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Cephalaspidomorphi
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Chondrichthyes
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Mammalia
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Myxini
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Cephalopoda
Geographic Coverages
Scotian Shelf, Gulf of Maine, Southern Gulf of St. Lawrence, Northwest Atlantic
Bibliographic Citations
- Chadwick, E. M. P., W. Brodie, E. Colbourne, D. Clark, D. Gascon, and T. Hurlbut. 2007. History of annual multi-species trawl surveys on the Atlantic Coast of Canada. AZMP Bulletin 6: 25-42. -
- Clark, D. S. and J. Emberley. 2008. Summer Scotian Shelf and Bay of Fundy Ecosystem update for 2008. CSAS Res Doc 2009/017 -
- Clark, D. S. and P. Perley. 2006. Summer Scotian Shelf and Bay of Fundy Ecosystem update 2006. CSAS Res Doc 2006/20; 53 p. -
- Tremblay, M.J.; Black, G.A.P.; Branton, R.M., 2007. The distribution of common decapod crustaceans and other invertebrates recorded in annual ecosystem surveys of the Scotian Shelf 1999-2006. Canadian technical report of fisheries and aquatic sciences; 2762; 74 p. -
Contacts
Don Clarkoriginator
Fisheries and Oceans Canada
St. Andrew's Biological Station, 531 Brandy Cove Road
St. Andrew's
E5B 2L9
New Brunswick
CA
email: don.clark@dfo-mpo.gc.ca
Helen Hayden
metadata author
position: Data manager
Fisheries and Oceans Canada
Bedford Institute of Oceanography
Dartmouth
B2Y 4A2
Nova Scotia
CA
email: helen.hayden@dfo-mpo.gc.ca
Paul Fanning
originator
position: retired
Fisheries and Oceans Canada
Bedford Institute of Oceanography
Dartmouth
B2Y 4A2
Nova Scotia
CA
Stephen Smith
originator
position: Head, Molluscan Fisheries
Fisheries and Oceans Canada
Bedford Institute of Oceanography
Dartmouth
B2Y 4A2
Nova Scotia
CA
email: stephen.smith@dfo-mpo.gc.ca
Helen Hayden
administrative point of contact
position: Data manager
Fisheries and Oceans Canada
Bedford Institute of Oceanography
Dartmouth
B2Y 4A2
Nova Scotia
CA
email: helen.hayden@dfo-mpo.gc.ca