NEFSC/Industry Cooperative Survey Gear Study 28 October – 6 November, 2002 To examine differences in catch rates of the R/V Albatross IV using standard.

NEFSC/Industry Cooperative Survey Gear Study28 October – 6 November, 2002

To examine differences in catch rates of the R/V Albatross IV using standard Yankee #36 trawls in two configurations; one configuration that conformed to standard specifications and a second configuration that was known not to meet specifications, including offset trawl warps.

OBJECTIVE

Source Document: Specifications for Construction of NEFSC Standard #36 Bottom Trawl

• General sampling areas provided by industry

• Specific areas determined onboard the ship

shallow - approximately 87 m (47.5 fm) in depthmid-depth - approximately 139 m (76 fm)deep - approximately 198 m (108 fm)

• Areas selected in order to cover a range of depths and to sample as many species as possible

SAMPLING AREAS

Original plan was to sample 2 areas in 1 depth zone then 2 areas in a second depth zoneWeather prevented occupation of 4 areas; therefore a third ‘shallow’ area was sampled

NEFSC/Industry CooperativeSurvey Gear Study – Part I

28 October – 6 November, 2002

Location of Sampling Areas

Area 1

Area 3

Area 2

Closed Area I

100m

BOTTOM PHOTO from NW CAI (Area 1)

Albatross Cruise 99-08, July 1998, Site I2Image provided by Page Valentine, USGS, Woods Hole Field Center

Albatross Cruise 99-08, July 1998, Site I2Image provided by Page Valentine, USGS, Woods Hole Field Center

BOTTOM PHOTO from NE CAI (Area 2)

• The areas were 5-minutes by 5-minutes (approximately 25 nm2)

• Each area was subdivided into 25 blocks, each 1-minute by 1-minute

• Each block was further subdivided into four quadrants

• Sixteen blocks were chosen, the maximum possible number of stations that could be performed during one 24 hour period, using uniformly distributed random numbers

• Stations were then placed in a randomly selected quadrant within each block

STATION SELECTION

4.75

4.25

3.75

3.25

2.75

2.25

1.75

1.25

0.75

0.25

012345

5

4

3

2

1

00.25

0.75

1.25

1.75

2.25

2.75

3.25

3.75

4.25

4.751 2 3 4 5

6 7 8 9 10

11 12 13 14 15

17 18 19 20

21 22 23 24 25

16

1

43

2

GRID USED TO POSITION TOW STARTING POINTS

• Each area sampled for 48 hours

• Order of gear configurations used determined by coin toss

• One randomly chosen gear configuration was used for 24 hours, then configurations switched and tows made at the same locations the following day

• Tows offset by approximately 1 additional hour to account for tide and light conditions

• Direction of tows determined by the Captain of the F/V Sea Breeze

• Constant scope used for all tows within an area. Scope chosen was that used for the deepest likely depth in an area

TOWING PROTOCOLS

SCOPE AND TRAWL WARP OFFSETS USED IN EACH SAMPLING AREA

Maximum AverageChart Depth Tow Depth Scope

m (fm) m (fm) m (fm) Feet Meters

Area 1: NW CAI 148 (81) 139.4 (76) 450 (246) 7'8" 2.3

Area 2: E Cape Cod 205 (112) 198.2 (108) 550 (301) 10'3" 3.1

Area 3: NE CAI 93 (51) 87.6 (48) 300 (164) 5'7" 1.7

Warp Offset

• Net #21, constructed prior to the experiment and inspected to meet the specifications by industry representatives

• Doors used (Pair #38) were inspected by industry representatives to meet tuned door specifications

• Backstraps used were fitted with swivels (with the appropriate number of links removed to maintain standard specification) to ensure that there were no twists in the chain while the net was fishing

• Even trawl warps; re-measured and certified the day of sailing

‘Optimal’ (OPT)

GEAR SPECIFICATIONS - R/V Albatross

‘Worst Case Scenario’ (WCS)

GEAR SPECIFICATIONS - R/V Albatross

• Net #14, used during the 24-27 October, 2002 ‘video cruise’ (the last 4 days of Leg II of AL 02-09, Autumn Bottom Trawl Survey)

• Pair #37 doors considered to be performing poorly during the ‘video cruise’

• Backstraps with no swivels and intentionally twisted 2 times

• Trawl warps offset to match the mis-marked warps used during 2001-2002 surveys

• Standard 6" mesh groundfish net

• 16” (with 12” at wings) rockhopper footrope with 2” cookies

• 110' sweep

• 30 fm groundcable used in Area 1• 50 fm groundcable used in Areas 2 and 3

• 2.4” (6 cm) mesh codend liner

GEAR SPECIFICATIONS - F/V Sea Breeze

Area DepthDoor

SpreadHeadrope

HeightDoor

SpreadHeadrope

HeightDoor

SpreadHeadrope

HeightMeters

1 139.4 24.01 -1 25.52 - 60.35 4.022 198.2 23.80 1.88 25.09 1.43 76.91 4.023 87.6 22.95 1.89 24.59 1.40 76.91 4.02

Means 23.59 1.89 25.07 1.42 71.39 4.02

Fathoms

1 76.1 13.1 - 13.9 - 332 2.2

2 108.2 13.0 1.0 13.7 0.8 423 2.2

3 47.8 12.5 1.0 13.4 0.8 42 2.2Means 12.9 1.0 13.7 0.8 39.0 2.2

1No headrope measurements from Albatross in Area 12Door Spread 32-34 fm3Door Spread 40-44 fm

Albatross IV 'WCS' Config

Albatross IV 'OPT' Config Sea Breeze

GEAR SPECIFICATIONS

Albatross IV TowsSea Breeze Tows

Location of Paired Tows Area 1: NW Closed Area I‘Optimal’ Configuration

Location of Paired Tows Area 1: NW Closed Area I‘Worst Case Scenario’ Configuration

Albatross IV TowsSea Breeze Tows

Albatross IV TowsSea Breeze Tows

Location of Paired Tows Area 1: NW Closed Area I29-30 October, 2002

Location of Paired Tows Area 2: East of Cape Cod‘Optimal’ Configuration

Albatross IV TowsSea Breeze Tows

Location of Paired Tows Area 2: East of Cape Cod‘Worst Case Scenario’ Configuration

Albatross IV TowsSea Breeze Tows

Albatross IV TowsSea Breeze Tows

Location of Paired Tows Area 2: NW Closed Area I31 October-3 November, 2002

Location of Paired Tows Area 3: NE Closed Area I‘Optimal’ Configuration

Albatross IV TowsSea Breeze Tows

Location of Paired Tows Area 3; NE Closed Area I‘Worst Case Scenario’ Configuration

Albatross IV TowsSea Breeze Tows

Albatross IV TowsSea Breeze Tows

Location of Paired Tows Area 3: NW Closed Area I3-5 November, 2002

Albatross• Catch sorted by species and weighed (nearest 0.001 kg) using motion compensated digital scales• Lengths of all fish measured (nearest cm)• All catch and biological data were recorded using the shipboard automated data entry system

Sea Breeze• Catch sorted by species and weighed using same scales• Individual fish lengths were taken on a subsample of the catch when time allowed• Catch weights were recorded on standard fisheries observer program logsheets and transmitted to the Albatross • Catch numbers and individual fish length data were also recorded on fisheries observer program logsheets and processed at the Woods Hole Laboratory the day after the cruise ended

SAMPLING PROTOCOLS

SUMMARY OF TOWS CONDUCTED IN EACH SAMPLING AREA

Albatross Albatross“OPT” Sea Breeze “WCS” Sea Breeze

Area 1: NW CAI 10 8 10 9Area 2: E Cape Cod 13 11 13 13Area 3: NE CAI 13 11 13 9Total - All Areas 36 30 36 31