Dataset: knotless codend_catch

Name: Knotless Codend Mesh Selectivity: fish catch data, Gulf of Maine, from F/V Jeanne C. NEC-KP2002-1 from April to July 2003 (NEC_ProjDev project)
Published: 2006-06-06
Keywords: oceans

Cite This Dataset

Project:

Northeast Consortium: Project Development (NEC_ProjDev)

Program:

NorthEast Consortium (NEC)

Principal Investigator:

Kelo Pinkham

Scientist:

Dana Morse (University of Maine)

Version:

6 June 2006

Version Date:

2006-06-06

Validated:

Yes

Current State:

Final no updates expected

Knotless Codend Mesh Selectivity: fish catch data, Gulf of Maine, from F/V Jeanne C. NEC-KP2002-1 from April to July 2003 (NEC_ProjDev project)

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Description

"Feasibility Study for Knotless Cod Ends"

report: Sea Trials to Assess Knotless Codend Mesh Selectivity by Dana L. Morse, Capt. Kelo Pinkham.

"The selectivity of knotless twine used in the codend of a groundfish trawl was tested relative to a standard codend constructed of knotted twine, in two companion projects. In 2003, 25 tow pair (50 tows) tests were conducted. Analysis of catch per unit effort and length frequency by species detected only a small difference between catches from the knotless and knotted codends. Video footage suggests a general tendency for the knotless twine to remain more fully open during trawling. Escapees from knotless codends may suffer less scale loss and other damage during the escape process. The knotless twine is lighter, easier to handle, and more supple. Future work should focus on the health of escapees, and on continued field trials, including square mesh arrangements. Larger sample sizes and covered codend experiments would help to more fully describe the selectivity of knotless twine in the Northeast groundfish fishery. Evaluations were somewhat hampered by low catches in both control and experimental tows. A research brief is available on the project, which describes some of the positives and negatives of using knotless twine." extracted from: Summary of Completed Cooperative Research Projects Funded by the Northeast Consortium, January 2006

Methods & Sampling

Movies taken during knotless codends experiment (by Bill Lee)
cod	knotless
whiting	knotless
hake	knotted
flounder	knotted

Data Files

File
knotless_codend.csv (Comma Separated Values (.csv), 3.93 KB) MD5:906eed0994606b058f0cc856ec1edeb6 Primary data file for dataset ID 2991

More Information about this dataset

Funding Sources

Funding Source	Award Number
National Oceanic and Atmospheric Administration	unknown NEC_ProjDev NOAA

Deployments

Deployment	Synonyms	Start Date	Platform	Investigator
NEC-KP2002-1		2003-04-01	F/V Jeanne C.	Kelo Pinkham (Chief Scientist)	data info

Instruments

Beam Trawl

Supplied Name: Trawl

Supplied Description:

groundfish trawl

Instrument Type

Generic Name: Beam Trawl

Acronym: Beam trawl

Community Identifier: http://vocab.nerc.ac.uk/collection/L05/current/24/

Generic 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)

Parameters

Date and time formats are described in python strftime() syntax.

Supplied Name	Supplied description	Supplied Units	Standard Name
species	which pair of fish or invertebrate is being tested		species
pair_no	1 through 25, each one representing a tow, i.e. two tows per pair		no_bcodmo_term
tow_length_control	length of tow in hours using knotted codend	hours	no_bcodmo_term
tow_length_exp	length of tow in hours using knotless codend	hours	no_bcodmo_term
weight_control	weight in pounds of catch from standard knotted codend	pounds	no_bcodmo_term
weight_exp	weight in pounds of catch from knotless twine being tested	pounds	no_bcodmo_term
cpue_control	catch per unit effort, pounds/hour, from knotted codend tow	pounds/hour	no_bcodmo_term
cpue_exp	catch per unit effort, pounds/hour, from knotless codend tow	pounds/hour	no_bcodmo_term

Database

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Dataset: knotless codend_catch