Dataset: raised web gillnets_metadata
Deployment: NEC-SE2005-1

Testing Raised-Webbing Gillnets to Reduce Bycatch of Cod While Targeting Pollock: haul data

Principal Investigator:

Steve Eayrs (Gulf of Maine Research Institute, GMRI)

Co-Principal Investigator:

Shale Rosen (Gulf of Maine Research Institute, GMRI)

Scientist:

Michael Pol (Massachusetts Division of Marine Fisheries)

Daniel J Salerno (Gulf of Maine Research Institute, GMRI)

BCO-DMO Data Manager:

Nancy Copley (Woods Hole Oceanographic Institution, WHOI BCO-DMO)

Project:

Northeast Consortium: Project Development (NEC_ProjDev)

Current State:

Final no updates expected

Version Date:

2011-10-20

Data URL:

https://www.bco-dmo.org/dataset-deployment/452443/data

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Description

Final Report: "Testing Raised-Webbing Gillnets to Reduce Bycatch of Cod While Targeting Pollock" by Daniel J. Salerno; submitted by Steve Eayrs & Daniel J. Salerno

Pollock is a Gadoid fish species that is a target for many commercial fishermen using sink gillnets in the Gulf of Maine. This gear is made up of a wall of webbing extending upwards from the seabed and are used to catch many demersal and benthic groundfish species. From a stock assessment perspective, pollock are considered to be healthy and robust stock as the stock is not overfished and overfishing is not occurring. However, other fish stocks such as Atlantic cod, white hake and yellowtail flounder are not as well off and are considered species of concern due to their stock status.

The ability to target healthy fish stocks with minimal impact to species of concern has become an essential issue for fishermen and managers in the New England region. Amendment 13 to the Northeast Multispecies Fishery Management Plan developed a measure for Special Access Programs to allow fishermen to access healthy fish stocks as long as there was minimal bycatch and impact on less robust stocks. With this in mind, two Gloucester based fishermen approach GMRI with a gillnet design that could potentialachieve this goal. Their design, based on observations made during commercial fishing trips, was to raise the webbing of gillnets off the seabed in order to decrease the Atlantic cod bycatch while targeting pollock. The raised-webbing would be attached across the bottom to a neutrally buoyant foot line which would be attached to the lead line by norsel lines.

Gear trials of the raised-webbing gillnets against standard commercial gear were conducted in the inshore and offshore waters in the Gulf of Maine in the winter of 2007 and 2008. Results indicated that the raised-webbing nets did indeed decrease catch, significantly for some species while maintaining similar catch rates for pollock. These results, however, should be treated as preliminary as it is believed that several factors during field trails may have influenced these findings. One factor specifically was the real time performance of the raised-webbing gillnets during the soak duration. (abstract from final report)

Methods & Sampling

Dataset acquisition description

2007
In January 2007, sea trials of the experimental gillnet gear were completed aboard the F/V Lady Shannon (State Reg. # MS10BM). Two strings of gillnets were constructed of six individual nets each, alternating between the experimental and standard net. The experimental nets were identical in configuration to the standard nets with the exception of the raised-webbing (Table 1). Both strings were set overnight in Massachusetts Bay. Individual species catch weight was recorded to tenths of kilograms separately for the experimental and standard nets.

	experimental net	standard net
number of nets per string	3	3
individual net length	300'	300'
net webbing height	12'	12'
norsel height	48"	0"
mesh size	7"	7"
vertical mesh count	25	25
twine size	0.62 mm	0.62 mm
hanging ratio	1/2	1/2

Table 1. Experimental and standard gillnet gear characteristics, 2007.

2008
As there were several research days left for field trials of the raised-webbing gillnets after the 2007 season, GMRI continued with testing the experimental gear in 2008. In February, sea trials of the experimental gear were conducted aboard the F/V Rachel T (State Reg. # ME685GG) in Massachusetts Bay and the offshore waters of the Gulf of Maine. Standard nets used during this time period differed from the experimental nets with respect to mesh size, vertical mesh count and twine size along with the raised-webbing (Table 2).

	experimental net	standard net
individual net length	300'	300'
net webbing height	12'	12'
norsel height	48"	0"
mesh size	7"	6.5"
vertical mesh count	25	0
twine size	0.62 mm	0.66 mm
hanging ratio	1/2	1/2

Table 2. Experimental and standard gillnet gear characteristics, 2008.

Data Processing Description

Dataset Processing Description

Data collected for this project included gillnet gear characteristics of the standard and experimental nets, location and timing of the sets and the associated catch data in kilograms as well as environmental data for all hauls conducted. Biological sampling included total weights for all species for both the experimental and control nets and fish lengths in centimeters were collected when sampling allowed. A Microsoft Office Access Database was created for data management and will be submitted for inclusion into the Northeast Consortium Fisheries & Ocean Database. (from final report)

More information about this dataset deployment

Funding

Award Number	Funding Source
PZ06115	National Oceanic and Atmospheric Administration

Instruments

Gillnet

Supplied Description:

gillnets raised off seabed

Instrument Type

Generic Name: Gillnet

Community Identifier: http://vocab.nerc.ac.uk/collection/L05/current/65/

Generic Description:

Gillnetting uses curtains of netting that are suspended by a system of floats and weights; they can be anchored to the sea floor or allowed to float at the surface. A gillnet catches fish by their gills because the twine of the netting is very thin, and either the fish does not see the net or the net is set so that it traps the fish.

Parameters

Supplied Name	Supplied description	Supplied Units	Standard Name
cruiseid	cruise identification		cruiseid
haul_num	haul number		no_bcodmo_term
lat_start	latitude at start of net setting	decimal degrees	lat_start
lon_start	longitude at start of net setting (west is negative)	decimal degrees	lon_start
lat_end	latitude at end of net haul	decimal degrees	lat_end
lon_end	longitude at end of haul (negative denotes West)	decimal degrees	lon_end
num_expt_nets	number of experimental nets deployed		no_bcodmo_term
num_ctrl_nets	number of control nets deployed		no_bcodmo_term
depth_fath	water depth at net deployment location	fathoms	depth
wind_spd_kts	wind speed	knots	wind_speed_kts
wind_dir	wind direction	degrees, magnetic	wind_dir
wave_hgt_ft	wave height	feet	no_bcodmo_term
soak_time	time from net set start to haul end		no_bcodmo_term
year	year of observation/experiment		year
day_local	day of month, 1-31		day_local
month_local	month, 1-12		month_local
yrday_local	local day and decimal time, as 326.5 for the 326th day of the year, or November 22 at 1200 hours (noon)		yrday_local

Database

Contribute Data

Dataset: raised web gillnets_metadataDeployment: NEC-SE2005-1

Dataset acquisition description

Dataset Processing Description

Dataset: raised web gillnets_metadata
Deployment: NEC-SE2005-1