http://lod.bco-dmo.org/id/dataset/3000
eng; USA
utf8
dataset
Highest level of data collection, from a common set of sensors or instrumentation, usually within the same research project
Biological and Chemical Oceanography Data Management Office (BCO-DMO)
Unavailable
508-289-2009
WHOI MS#36
Woods Hole
MA
02543
USA
info@bco-dmo.org
http://www.bco-dmo.org
Monday - Friday 8:00am - 5:00pm
For questions regarding this resource, please contact BCO-DMO via the email address provided.
pointOfContact
2010-06-16
ISO 19115-2 Geographic Information - Metadata - Part 2: Extensions for Imagery and Gridded Data
ISO 19115-2:2009(E)
Improving the Size Selectivity for Northern Shrimp Through Use of a Combination of a Modified Nordmore Grate and Square Mesh Cod End: tows from the F/V Jeanne C, Gulf of Maine, 2003-2004 (NEC-CoopRes project)
2009-01-16
publication
2009-01-16
revision
BCO-DMO Linked Data URI
2009-01-16
creation
http://lod.bco-dmo.org/id/dataset/3000
Kelo Pinkham
principalInvestigator
Dr Daniel Schick
Maine Department of Marine Resources
principalInvestigator
Biological and Chemical Oceanography Data Management Office (BCO-DMO)
Unavailable
508-289-2009
WHOI MS#36
Woods Hole
MA
02543
USA
info@bco-dmo.org
http://www.bco-dmo.org
Monday - Friday 8:00am - 5:00pm
For questions regarding this resource, please contact BCO-DMO via the email address provided.
publisher
Cite this dataset as: Pinkham, K., Schick, D. (2009) Improving the Size Selectivity for Northern Shrimp Through Use of a Combination of a Modified Nordmore Grate and Square Mesh Cod End: tows from the F/V Jeanne C, Gulf of Maine, 2003-2004 (NEC-CoopRes project). Biological and Chemical Oceanography Data Management Office (BCO-DMO). (Version 16 Jan 2009) Version Date 2009-01-16 [if applicable, indicate subset used]. http://lod.bco-dmo.org/id/dataset/3000 [access date]
Improving the Size Selectivity for Northern Shrimp Through Use of a Combination of a Modified Nordmore Grate and Square Mesh Cod End, Gulf of Maine, 2003-2004: tow chedule Dataset Description: <p><strong>Improving the Size Selectivity for Northern Shrimp Through Use of a Combination of a Modified Nordmore Grate and Square Mesh Cod End</strong></p>
<p><a href="http://northeastconsortium.org/ProjectFileDownload.pm?report_id=708&amp;table=project_report" target="_blank">Final report</a> by Daniel Schick, Kelo Pinkham and Lessie White.</p>
<p>This dataset lists all trawl modifications and test dates. See also:<br />
*shrimp_nord_sumry - summarizes the test results for the various trawl modifications, with statistical analysis.<br />
*shrimp_nordgrate - large and small shrimp catch data</p>
<table align="center" border="1" cellpadding="3" cellspacing="0">
<tbody>
<tr>
<td><strong>gear code</strong></td>
<td><strong>description of gear</strong></td>
</tr>
<tr>
<td>qtr_grate</td>
<td>1/4-length small bar space section</td>
</tr>
<tr>
<td>half_grate</td>
<td>1/2-length small bar space section</td>
</tr>
<tr>
<td>std</td>
<td>standard Nordmore grate/diamond cod end</td>
</tr>
<tr>
<td>mesh bag behind grate</td>
<td>with small mesh bag attached behind the small bar space grate</td>
</tr>
<tr>
<td dir="ltr">mesh bag over escape hole</td>
<td dir="ltr">with small mesh bag over escape hole</td>
</tr>
<tr>
<td>no_grate</td>
<td>no grate</td>
</tr>
<tr>
<td>StdDD</td>
<td>standard Nordmore grate/cod end</td>
</tr>
<tr>
<td>716DD</td>
<td>7/16" Bent Grate Diamond lengthener, diamond cod end</td>
</tr>
<tr>
<td>716DS</td>
<td>7/16"bent grate diamond lengthener, square cod end</td>
</tr>
<tr>
<td>716SD</td>
<td>7/16" Bent Grate Square Mesh Lengthener, Diamond Cod End</td>
</tr>
<tr>
<td>716SS</td>
<td>7/16" Bent Grate Square Mesh Lengthener, Square Mesh Cod End</td>
</tr>
<tr>
<td>TapDD</td>
<td>tapered, bent grate was placed in a diamond lengthening piece and fished with a diamond mesh cod end</td>
</tr>
<tr>
<td>TapDS</td>
<td>tapered, bent grate was placed in a diamond lengthening piece and fished with a square mesh cod end</td>
</tr>
<tr>
<td>TapSD</td>
<td>Tapered Bent Grate Square Mesh Lengthener, Diamond Cod End</td>
</tr>
<tr>
<td>TapSS</td>
<td>Tapered Bent Grate Square Mesh Lengthener, Square Mesh Cod End</td>
</tr>
</tbody>
</table>
<p><strong>Abstract</strong></p>
<p>Comparative tows with a trouser trawl were conducted to test improved release of small shrimp and fish and retention of large shrimp using various configurations of a compound Nordmore grate and diamond or square mesh in the lengthening piece and cod end. The forward (upper) grate section had small bar spacing (7/16") sized to allow small shrimp to flow between the bars and escape. The aft (lower) section had ¾" bar spacing to allow large shrimp to flow between the bars and into the cod end mounted behind this section. Two sizes of small bar space section, ½ and ¼ of the total length were tested. The ½ length section released more small shrimp but also retained less large shrimp than the ¼ length section compared to a standard Nordmore grate/cod end. The large shrimp were flowing out the escape hole at the bottom of the compound grate. The aft section was lengthened for better retention of large shrimp and the small bar space section was tilted (bent) another 10 degrees to improve small shrimp release. A small bar space section with tapered openings was added to the test series as was square mesh in the lengthener and/or cod end. The two modified compound grates with the four mesh combinations produced eight test series where each gear type was judged for finfish release, shrimp weight retained, small shrimp release and large shrimp retention. The best combination was the 7/16" bar space bent grate with diamond lengthener and square mesh cod end.</p> Methods and Sampling: <p><strong>Methods</strong></p>
<!-- br-->
<p>The research spanned two years. In the first year's study, the compound grate tested was mounted in the net upside down so that the small bar spacing was at the top of the grate and the larger bar spacing was at the bottom of the net with the escape hole in the bottom. The upper edge of the cod end is attached to the grate at the juncture between the small bar spaces and the larger bar spaces. All shrimp and finfish were directed to the top of the grate where the small shrimp and finfish were able to pass through the small bar spacing (7/16") and exit the net. The larger fish and marketable shrimp worked their way down to the larger bar spacing (3/4") where the shrimp and some fish would pass through into the cod end and lobsters and remaining fish worked their way down and out through the escape hole. Two different grate surface areas of small bar spacing were tested. One of the compound grates had one quarter of the grate small bar spacing (10" of the 40" grate were spaced 7/16" apart) while the other compound grate was comprised of half the grate with small bar spacing (20" of the 40" grate were spaced 7/16" apart). A second cod end of smaller mesh was constructed to fit behind the small bar space panel to collect what was escaping through these bars on over the escape hole to determine if shrimp were being lost out through this hole.</p>
<p>The compound grate was tested using a trouser trawl, a dual cod end trawl split vertically down the middle (Figure 1). One lengthener/cod end held the experimental device while the other cod end was used as the control in a series of experiments. As there is always a question concerning bias in a split trawl as to weather the two halves fish equally, both lengtheners and both cod ends were attached to the trawl with a quick release zipper so that they could be switched between sides.</p>
<p>Each of the panel sizes (1/4 small bar spaces and 1/2 small bar spaces) was tested by a series of tows against a standard Nordmore grate and each side had a standard 1/3/4" diamond mesh cod end. Each panel size was also towed with and without the small mesh cod end behind the small bar space panel. The species weights and length frequencies in the cod ends were compared to determine any differences in the catch. The length frequency in the regular cod end was also compared to the length frequency in the small mesh cod end to test against the possibility of back pressure affecting the flow through the bars of the small bar space panel. The tow series to conduct these tests switched the standard and experimental units between sides to reduce any possible side effect with the trouser trawl (Table 1).</p>
<p>In the second series of tests the next year the study built upon the results of the first year and modified the grate structure to improve loss of finfish and small shrimp and retention of large shrimp. We used the half grate configuration, elongated the grate and tipped the upper, small bar space half about 10 degrees more towards the front of the net to improve movement of shrimp and fish down that portion of the grate. With this change, two bar space widths were tested in the upper, small bar space section, a straight 7/16" grid and a trapezoidal grid with tapered bar spacing increasing from 5/16" to 1/2" front to back. Each of these bar space configurations were tested with diamond mesh in both the lengthener around the grate and the cod end, with square mesh in the cod end only, with square mesh in the lengthener only and with square mesh in both the lengthener and cod end to see which combination resulted in the best separation of fish and small shrimp from the market shrimp. The extra sets of tow with the small mesh bag behind the small bar space grate and with small mesh bags behind the small bar space grate and over the escape hole were not conducted in the second year due to time and funding constraints. The tow series to conduct the second years' tests switched the standard and experimental units between sides to reduce any possible side effect with the trouser trawl (Table 2).</p>
<p>In looking at the boat procedure there were a couple of things that had to be determined. The first was the total time to tow the net. The average tow time for the Maine shrimp fishery from 2001 through 2004 was 2.1 hours per tow with fishermen getting in about 3 or 4 tows a day. The other factor in determining the duration of the tow was to get as many replications as possible with the budget and time we had. One hour tows were chosen in order to remain as close as possible to realistic fishing conditions while getting in 3 or 4 extra replications per day. The tow time started at the started. The date, starting time, ending time, starting latitude, ending latitude, starting longitude, ending longitude, starting depth, ending depth, tow speed, wire out and gear type on the starboard and port sides of the trouser trawl were all recorded for each tow. Once the cod ends came on board the boat the starboard cod end was emptied onto the sorting table. The port cod end was emptied into fish trays. The shrimp were then separated from the fish in the starboard catch. The fish were separated further by species and a total weight by species was recorded along with the individual lengths of each fish. In the cases where there were quite a few fish a weighed sub-sample was taken. The total shrimp catch was then weighed and a 1-kilogram sub-sample of shrimp was brought back to the lab for further analysis. Once done with the starboard side the process was repeated for the port side catch. The catch from the mesh bags behind the small bar space grate, or over the escape hole, when employed, was sorted and measured in a similar fashion.</p>
<p>During the lab analysis of the 1-kilogram sub-sample the shrimp are sorted by species and the Pandalus borealis are sorted by sexual stage. For the non Pandalus borealis species total weights for each species are obtained along with individual carapace lengths. For Pandalus borealis the total weights for each sexual stage is recorded. Then for each sexual stage the individual carapace lengths are recorded. This information is used to generate sex-specific length frequency distributions, thus providing information on the size and age composition of each of the catches.</p>
Funding provided by National Oceanic and Atmospheric Administration (NOAA) Award Number: unknown NEC-CoopRes NOAA
completed
Kelo Pinkham
(207) 633-6315 (home)
187 West Side Road
Trevett
ME
04571
USA
kpinkham@gwi.net
pointOfContact
Dr Daniel Schick
Maine Department of Marine Resources
(207) 633-9500
PO Box 8
West Boothbay Harbor
ME
04575
USA
dan.schick@maine.gov
pointOfContact
asNeeded
Dataset Version: 16 Jan 2009
Unknown
gear
position
tow
shrimp_caught
year
month_local
day_local
yrday_local
Trawl
theme
None, User defined
No BCO-DMO term
tow
count
year
month_local
day_local
day of year and decimal time (local time zone)
featureType
BCO-DMO Standard Parameters
Beam Trawl
instrument
BCO-DMO Standard Instruments
NEC-KP2003-1
service
Deployment Activity
Gulf of Maine
place
Locations
otherRestrictions
otherRestrictions
Access Constraints: none. Use Constraints: Please follow guidelines at: http://www.bco-dmo.org/terms-use Distribution liability: Under no circumstances shall BCO-DMO be liable for any direct, incidental, special, consequential, indirect, or punitive damages that result from the use of, or the inability to use, the materials in this data submission. If you are dissatisfied with any materials in this data submission your sole and exclusive remedy is to discontinue use.
NorthEast Consortium
http://northeastconsortium.org/
NorthEast Consortium
The Northeast Consortium encourages and funds
cooperative research and monitoring projects in the Gulf of Maine and Georges Bank that have effective,
equal partnerships among fishermen, scientists, educators, and marine resource managers.
At the 2008 Maine Fisheremen's Forum, the Northeast Consortium organized a session on data collection and availability. Participants included several key organizations in the Gulf of Maine area, sharing what data are out there and how you can find them.
The Northeast Consortium has joined the Gulf of Maine Ocean Data Partnership. The purpose of the GoMODP is to promote and coordinate the sharing, linking, electronic dissemination, and use of data on the Gulf of Maine region.
The Northeast Consortium was created in 1999 to encourage and fund effective, equal partnerships among commercial fishermen, scientists, and other stakeholders to engage in cooperative research and monitoring projects in the Gulf of Maine and Georges Bank. The Northeast Consortium consists of four research institutions (University of New Hampshire, University of Maine, Massachusetts Institute of Technology, and Woods Hole Oceanographic Institution), which are working together to foster this initiative.
The Northeast Consortium administers nearly $5M annually from the National Oceanic and Atmospheric Administration for cooperative research on a broad range of topics including gear selectivity, fish habitat, stock assessments, and socioeconomics. The funding is appropriated to the National Marine Fisheries Service and administered by the University of New Hampshire on behalf of the Northeast Consortium. Funds are distributed through an annual open competition, which is announced via a Request for Proposals (RFP). All projects must involve partnership between commercial fishermen and scientists.
The Northeast Consortium seeks to fund projects that will be conducted in a responsible manner. Cooperative research projects should be designed to minimize any negative impacts to ecosystems or marine organisms, and be consistent with accepted ethical research practices, including the use of animals and human subjects in research, scrutiny of research protocols by an institutional board of review, etc.
NEC
largerWorkCitation
program
Northeast Consortium: Cooperative Research
http://northeastconsortium.org/
Northeast Consortium: Cooperative Research
<p>The Northeast Consortium encourages and funds cooperative research and monitoring projects in the Gulf of Maine and Georges Bank that have effective, equal partnerships among fishermen, scientists, educators, and marine resource managers.</p>
<p>The Northeast Consortium seeks to fund projects that will be conducted in a responsible manner. Cooperative research projects are designed to minimize any negative impacts to ecosystems or marine organisms, and be consistent with accepted ethical research practices, including the use of animals and human subjects in research, scrutiny of research protocols by an institutional board of review, etc.</p>
NEC-CoopRes
largerWorkCitation
project
eng; USA
oceans
Gulf of Maine
2009-01-16
Georges Bank, Gulf of Maine
0
BCO-DMO catalogue of parameters from Improving the Size Selectivity for Northern Shrimp Through Use of a Combination of a Modified Nordmore Grate and Square Mesh Cod End: tows from the F/V Jeanne C, Gulf of Maine, 2003-2004 (NEC-CoopRes project)
Biological and Chemical Oceanography Data Management Office (BCO-DMO)
Unavailable
508-289-2009
WHOI MS#36
Woods Hole
MA
02543
USA
info@bco-dmo.org
http://www.bco-dmo.org
Monday - Friday 8:00am - 5:00pm
For questions regarding this resource, please contact BCO-DMO via the email address provided.
pointOfContact
http://lod.bco-dmo.org/id/dataset-parameter/14616.rdf
Name: gear
Units: unknown
Description: <p>configuration of trawl (see above)</p>
http://lod.bco-dmo.org/id/dataset-parameter/14617.rdf
Name: position
Units: unknown
Description: <p>position of modification of gear, port or starboard side of trouser trawl.</p>
http://lod.bco-dmo.org/id/dataset-parameter/14618.rdf
Name: tow
Units: dimensionless
Description: <p>sequential tow number</p>
http://lod.bco-dmo.org/id/dataset-parameter/14619.rdf
Name: shrimp_caught
Units: unknown
Description: <p>whether or not shrimp were caught in cod end sample. x=yes; o=no; nd=not recorded</p>
http://lod.bco-dmo.org/id/dataset-parameter/14620.rdf
Name: year
Units: unknown
Description: <p>year, e.g. 2009</p>
http://lod.bco-dmo.org/id/dataset-parameter/14621.rdf
Name: month_local
Units: unknown
Description: <p>month of year, local time</p>
http://lod.bco-dmo.org/id/dataset-parameter/14622.rdf
Name: day_local
Units: unknown
Description: <p>numerical day of the month, local time </p>
http://lod.bco-dmo.org/id/dataset-parameter/14623.rdf
Name: yrday_local
Units: unknown
Description: <p>local day and decimal time, as 326.5 for the 326th day of the year, or November 22, at 1200 hours (noon)</p>
GB/NERC/BODC > British Oceanographic Data Centre, Natural Environment Research Council, United Kingdom
Biological and Chemical Oceanography Data Management Office (BCO-DMO)
Unavailable
508-289-2009
WHOI MS#36
Woods Hole
MA
02543
USA
info@bco-dmo.org
http://www.bco-dmo.org
Monday - Friday 8:00am - 5:00pm
For questions regarding this resource, please contact BCO-DMO via the email address provided.
pointOfContact
102914
https://datadocs.bco-dmo.org/file/6YYMw11io0jVrB/shrimp_nord_tows.csv
shrimp_nord_tows.csv
Primary data file for dataset ID 3000
download
https://osprey.bco-dmo.org/dataset/3000/data/download
download
onLine
dataset
<p><strong>Methods</strong></p>
<!-- br-->
<p>The research spanned two years. In the first year's study, the compound grate tested was mounted in the net upside down so that the small bar spacing was at the top of the grate and the larger bar spacing was at the bottom of the net with the escape hole in the bottom. The upper edge of the cod end is attached to the grate at the juncture between the small bar spaces and the larger bar spaces. All shrimp and finfish were directed to the top of the grate where the small shrimp and finfish were able to pass through the small bar spacing (7/16") and exit the net. The larger fish and marketable shrimp worked their way down to the larger bar spacing (3/4") where the shrimp and some fish would pass through into the cod end and lobsters and remaining fish worked their way down and out through the escape hole. Two different grate surface areas of small bar spacing were tested. One of the compound grates had one quarter of the grate small bar spacing (10" of the 40" grate were spaced 7/16" apart) while the other compound grate was comprised of half the grate with small bar spacing (20" of the 40" grate were spaced 7/16" apart). A second cod end of smaller mesh was constructed to fit behind the small bar space panel to collect what was escaping through these bars on over the escape hole to determine if shrimp were being lost out through this hole.</p>
<p>The compound grate was tested using a trouser trawl, a dual cod end trawl split vertically down the middle (Figure 1). One lengthener/cod end held the experimental device while the other cod end was used as the control in a series of experiments. As there is always a question concerning bias in a split trawl as to weather the two halves fish equally, both lengtheners and both cod ends were attached to the trawl with a quick release zipper so that they could be switched between sides.</p>
<p>Each of the panel sizes (1/4 small bar spaces and 1/2 small bar spaces) was tested by a series of tows against a standard Nordmore grate and each side had a standard 1/3/4" diamond mesh cod end. Each panel size was also towed with and without the small mesh cod end behind the small bar space panel. The species weights and length frequencies in the cod ends were compared to determine any differences in the catch. The length frequency in the regular cod end was also compared to the length frequency in the small mesh cod end to test against the possibility of back pressure affecting the flow through the bars of the small bar space panel. The tow series to conduct these tests switched the standard and experimental units between sides to reduce any possible side effect with the trouser trawl (Table 1).</p>
<p>In the second series of tests the next year the study built upon the results of the first year and modified the grate structure to improve loss of finfish and small shrimp and retention of large shrimp. We used the half grate configuration, elongated the grate and tipped the upper, small bar space half about 10 degrees more towards the front of the net to improve movement of shrimp and fish down that portion of the grate. With this change, two bar space widths were tested in the upper, small bar space section, a straight 7/16" grid and a trapezoidal grid with tapered bar spacing increasing from 5/16" to 1/2" front to back. Each of these bar space configurations were tested with diamond mesh in both the lengthener around the grate and the cod end, with square mesh in the cod end only, with square mesh in the lengthener only and with square mesh in both the lengthener and cod end to see which combination resulted in the best separation of fish and small shrimp from the market shrimp. The extra sets of tow with the small mesh bag behind the small bar space grate and with small mesh bags behind the small bar space grate and over the escape hole were not conducted in the second year due to time and funding constraints. The tow series to conduct the second years' tests switched the standard and experimental units between sides to reduce any possible side effect with the trouser trawl (Table 2).</p>
<p>In looking at the boat procedure there were a couple of things that had to be determined. The first was the total time to tow the net. The average tow time for the Maine shrimp fishery from 2001 through 2004 was 2.1 hours per tow with fishermen getting in about 3 or 4 tows a day. The other factor in determining the duration of the tow was to get as many replications as possible with the budget and time we had. One hour tows were chosen in order to remain as close as possible to realistic fishing conditions while getting in 3 or 4 extra replications per day. The tow time started at the started. The date, starting time, ending time, starting latitude, ending latitude, starting longitude, ending longitude, starting depth, ending depth, tow speed, wire out and gear type on the starboard and port sides of the trouser trawl were all recorded for each tow. Once the cod ends came on board the boat the starboard cod end was emptied onto the sorting table. The port cod end was emptied into fish trays. The shrimp were then separated from the fish in the starboard catch. The fish were separated further by species and a total weight by species was recorded along with the individual lengths of each fish. In the cases where there were quite a few fish a weighed sub-sample was taken. The total shrimp catch was then weighed and a 1-kilogram sub-sample of shrimp was brought back to the lab for further analysis. Once done with the starboard side the process was repeated for the port side catch. The catch from the mesh bags behind the small bar space grate, or over the escape hole, when employed, was sorted and measured in a similar fashion.</p>
<p>During the lab analysis of the 1-kilogram sub-sample the shrimp are sorted by species and the Pandalus borealis are sorted by sexual stage. For the non Pandalus borealis species total weights for each species are obtained along with individual carapace lengths. For Pandalus borealis the total weights for each sexual stage is recorded. Then for each sexual stage the individual carapace lengths are recorded. This information is used to generate sex-specific length frequency distributions, thus providing information on the size and age composition of each of the catches.</p>
Specified by the Principal Investigator(s)
<p>The data obtained for this research are the trawl haul logs and laboratory measurements of the shrimp for each sample. The trawl haul logs contain the typical information on location, date, time, depth, at the beginning and end of the tow. They also contain the catch information in weight and numbers by species for all finfish and the shrimp aggregate weight. From the subsample of shrimp brought to the lab, species weights and numbers at size for all shrimp and for Northern shrimp, Pandalus borealis, weights and numbers at size for each sex.</p>
<table align="center" border="0" cellpadding="5" cellspacing="5" style="width:66%">
<tbody>
<tr>
<td><img alt="nordmore grate" src="https://datadocs.bco-dmo.org/static/nec.whoi.edu/images/nordmore_grate.jpg" style="height:301px; width:228px" /></td>
<td><a href="http://www.dfo-mpo.gc.ca/communic/fish_man/ifmpns-pgipcn/index_e.htm"><img alt="nordmore_grate_diagram" src="https://datadocs.bco-dmo.org/static/nec.whoi.edu/images/nordmore_grate_diagrm.jpg" style="float:right; height:301px; width:450px" /></a></td>
</tr>
<tr>
<td>Normore grate <em>(Photo: Ken La Valley)</em></td>
<td>Diagram of Nordmore grate</td>
</tr>
</tbody>
</table>
Specified by the Principal Investigator(s)
asNeeded
7.x-1.1
Biological and Chemical Oceanography Data Management Office (BCO-DMO)
Unavailable
508-289-2009
WHOI MS#36
Woods Hole
MA
02543
USA
info@bco-dmo.org
http://www.bco-dmo.org
Monday - Friday 8:00am - 5:00pm
For questions regarding this resource, please contact BCO-DMO via the email address provided.
pointOfContact
Trawl
Trawl
PI Supplied Instrument Name: Trawl PI Supplied Instrument Description:Trouser trawl using various configurations of a compound Nordmore grate and diamond or square mesh in the lengthening piece and cod end. Instrument Name: Beam Trawl Instrument Short Name:Beam trawl Instrument Description: A beam trawl consists of a cone-shaped body ending in a bag or codend, which retains the catch. In these trawls the horizontal opening of the net is provided by a beam, made of wood or metal, which is up to 12 m long. The vertical opening is provided by two hoop-like trawl shoes mostly made from steel. No hydrodynamic forces are needed to keep a beam trawl open. The beam trawl is normally towed on outriggers, one trawl on each side.
While fishing for flatfish the beam trawl is often equipped with tickler chains to disturb the fish from the seabed. For operations on very rough fishing grounds they can be equipped with chain matrices. Chain matrices are rigged between the beam and the groundrope and prevent boulders/stones from being caught by the trawl. Shrimp beam trawls are not so heavy and have smaller mesh sizes. A bobbin of groundrope with rubber bobbins keeps the shrimp beam trawl in contact with the bottom and gives flatfish the opportunity to escape.
Close bottom contact is necessary for successful operation. To avoid bycatch of most juvenile fishes selectivity devices are assembled (sieve nets, sorting grids, escape holes). While targeting flatfish the beam trawls are towed up to seven knots, therefore the gear is very heavy; the largest gears weighs up to 10 ton. The towing speed for shrimp is between 2.5 and 3 knots.
(from: http://www.fao.org/fishery/geartype/305/en) Community Standard Description: http://vocab.nerc.ac.uk/collection/L05/current/24/
Cruise: NEC-KP2003-1
NEC-KP2003-1
F/V Jeanne C.
vessel
NEC-KP2003-1
Kelo Pinkham
http://northeastconsortium.org/ProjectFileDownload.pm?report_id=708&table=project_report
Report describing NEC-KP2003-1
F/V Jeanne C.
vessel