NOAA NMFS SWFSC FED Trawling Protocols 2020.pdf

National Oceanic and Atmospheric Administration National Marine Fisheries Service

Southwest Fisheries Science Center Fisheries Ecology Division

Santa Cruz, California

Operations Manual Rockfish Recruitment and Ecosystem Assessment Survey

Trawling Protocols

Keith Sakuma Ken Baltz John Field

Stephen Ralston

April 2020

Rockfish Recruitment and Ecosystem Assessment Survey Trawling Protocols

Table of Contents

Section Page

Introduction 3

Operational protocols for midwater trawling 3

Midwater trawl station selection 3 Achieving target headrope depth 6

Duration of trawl deployments 7 Recording trawling operations information 8 Handling the trawl net and the catch 8

Problems occurring during trawl operations 9 Mitigating interaction with protected species 9

Trawl construction and repair 11 Midwater trawl description 11 Net plan 13 Codend liner plan 14 Door plan 15 Rigging diagram 16 Net construction materials list 17 Trawl warp specification 19

Trawl repair checklist 20

Appendix 23

Warp measurement on the NOAA Ship DAVID STARR JORDAN Calibration of the NOAA Ship DAVID STARR JORDAN’s electronic block counter system

Introduction

Since 1983 the Groundfish Analysis Team of the National Oceanic and Atmospheric Administration (NOAA) National Marine Fisheries Service (NMFS), Southwest Fisheries Science Center (SWFSC), Fisheries Ecology Division (FED) has conducted annual rockfish recruitment and ecosystem assessment surveys during late spring (April-June) along the central California coast. In 2004 the survey area was expanded to encompass nearly the entire coast of California with additional northern stations added in 2013. From 1983 to 2008 surveys were conducted aboard the NOAA Ship DAVID STARR JORDAN. The following ships were used after the NOAA Ship DAVID STARR JORDAN was decommissioned in 2008: NOAA Ship MILLER FREEMAN in 2009, fishing vessel FROSTI in 2010, fishing vessel EXCALIBUR in 2011, NOAA Ship BELL M. SHIMADA in 2012, and research vessel OCEAN STARR (the former NOAA Ship DAVID STARR JORDAN purchased and refurbished by Stabbert Maritime) in 2013- 2015. Since 2016 surveys have been conducted on the NOAA Ship REUBEN LASKER.

Midwater trawling operations are conducted during nighttime hours due to potential net avoidance during daylight hours. The objective is to sample pelagic juvenile rockfishes (Sebastes spp.) and other important species such as juvenile Pacific whiting (Merluccius productus), juvenile lingcod (Ophiodon elongatus), northern anchovy (Engraulis mordax), Pacific sardine (Sardinops sagax), market squid (Doryteuthis opalescens), and krill (Euphausiacea) to determine their distribution and abundance.

Operational protocols for midwater trawling

Midwater trawl station selection

In general, 4-7 midwater trawling operations are conducted each night between 2100- 0600 PST. Standard stations are sampled 2 to 3 times during the survey with temporal separation between replicates. Following is a list with the positions, the bottom depths, the estimated trawl warp to reach target headrope depths of 30 m (~85 m Warp) and 10 m (~25 m Warp), and the unique station number for the currently active standard stations.

Standard stations

Latitude Longitude Bottom depth (m) Warp (m) Station number 33 01' 117 45' 798 85 481 32 55' 117 35' 865 85 482 32 49' 117 25.3' 555 85 483 32 42.5' 117 20' 94 85 484 32 43' 118 12' 1586 85 401 32 43' 118 27.2' 222 85 402 32 43' 118 44.9' 1253 85 403 32 43' 119 01' 777 85 404 33 41.4' 119 17.2' 892 85 411

33 35.2' 119 26.9' 1874 85 412 33 29.2' 119 36.3' 775 85 413 33 23' 119 45.8' 103 85 414 34 19.1' 120 18' 380 85 422 34 10.6' 120 28.3' 122 85 423 34 04.2' 120 34.7' 190 85 424 33 55.1' 120 42.7' 1848 85 425 35 00' 120 44' 55 25 491 35 00' 120 47.6' 94 85 492 35 00' 120 53' 192 85 493 35 00' 120 58.5' 374 85 494 35 00' 121 07' 532 85 495 35 42.2' 121 21.8' 60 85 441 35 42.2' 121 25.8' 167 85 442 35 42.2' 121 30.5' 557 85 443 35 42.2' 121 42' 885 85 444 35 42.2' 121 52' 1050 85 445 36 18' 121 56.3' 65 85 101 36 18' 122 00.9' 102 85 103 36 18' 122 05.4' 354 85 104 36 18' 122 11.5' 828 85 105 36 18' 122 18.5' 928 85 106 36 35' 122 02' 608 85 109 36 35' 122 10.5' 2304 25 110 36 35' 122 19.5' 2516 85 211 36 35' 122 31' 2997 85 212 36 42' 122 06.5' 1920 85 117 36 39.3' 121 56.8' 73 85 112 36 38.8' 122 03' 900 85 113 36 46' 121 52' 73 85 114 36 42.5' 121 54.5 91 85 115 36 44.4' 121 58.6' 287 85 116 36 50.8' 121 59' 91 85 119 36 59' 122 17.5' 82 85 123 36 59' 122 22.5' 128 85 124 36 59' 122 25.5' 446 85 125 36 59' 122 35.5' 432 85 126 36 59' 122 45.5' 1045 85 127 37 16.5' 122 34' 82 85 131 37 16.5' 122 39' 95 85 132 37 16.5' 122 49' 184 85 133 37 16.5' 122 59' 518 85 134

37 16.5' 123 09' 950 85 135 37 42' 122 54.5' 55 25 138 37 47.5' 122 52' 55 25 139 37 35.8' 122 49.9' 74 25 237 37 39.5' 123 02.5' 108 85 152 37 39.5' 123 12.5' 1301 85 154 37 44.6' 123 08.3' 91 85 156 37 53' 123 19' 91 85 160 37 53' 123 30' 1328 85 162 38 10' 123 00' 55 25 165 38 10' 123 10' 91 85 167 38 10' 123 22' 183 85 170 38 10' 123 29' 400 85 171 38 10' 123 42.5' 2063 85 174 38 28' 123 14' 53 85 183 38 28' 123 23.2' 115 85 453 38 28' 123 42.6' 910 85 454 38 28' 124 03.5' 3263 85 455 39 08' 123 47' 73 85 461 39 08' 124 00' 404 85 463 39 08' 124 19' 2153 85 464 39 08' 124 36' 3292 85 465 39 50' 123 55' 65 85 471 39 50' 124 06.5' 236 85 473 39 50' 124 24' 1600 85 474 39 50' 124 43' 1344 85 475 40 30’ 124 31.6’ 61 85 601 40 30’ 124 37.2’ 187 85 602 40 30’ 124 43.8’ 1622 85 603 40 30’ 124 57’ 2565 85 605 40 30’ 125 10.2’ 2634 85 607 41 0’ 124 16.2’ 79 85 611 41 0’ 124 22.8’ 192 85 612 41 0’ 124 29.4’ 520 85 613 41 0’ 124 42.6’ 743 85 615 41 0’ 124 55.8’ 2804 85 617 41 30’ 124 15.6’ 66 85 621 41 30’ 124 22.2’ 96 85 622 41 30’ 124 28.8’ 169 85 623 41 30’ 124 42’ 946 85 625 41 30’ 124 55.2’ 690 85 627

The starting position for a trawl should be as close as possible to the listed standard station position. However, starting position can also be 1 nm away from the standard station position as long as the vessel then tows towards the station. In addition, the starting or ending position for a trawl should not be in excess of two nautical miles from the standard station position. In rare instances, navigational constraints may not allow a trawl to occur within a two nautical mile radius of the specific station location. These situations will be evaluated on a case-by-case basis by the Chief Scientist/Cruise Leader to determine the appropriate course of action.

Achieving target headrope depth

Target headrope depth is a primary criterion for trawl standardization and consistency.

Target headrope depths are achieved and maintained by the amount of wire out for the trawl warps and a rate of speed through the water.

Beginning in 1993, temperature depth recorders (TDR) were attached to the headrope bridle. The current ReefNet TDRs are rated for a maximum depth of 150 meters and housed in a PVC tube for protection. TDRs record every 10 seconds and provide retrospective data on headrope depth and water temperature.

From 2003 - 2008, Simrad integrated trawl instrumentation (ITI) acoustic sensors (trawl-eye, temperature-depth, port and starboard wing spread) were attached to the headrope and net wings (near breast lines) during deployments. The ITI sensors were clearly marked with respect to their orientation (i.e. Up, Towards Vessel, Port, and Starboard) for ease of attachment to the trawl net. The trawl eye sensor measured head rope height and foot rope clearance, the temperature-depth sensor measured the headrope depth and temperature, and the pair of wing sensors (port and starboard, one master and one slave) measured the wing spread. All ITI data were logged and displayed in real-time with recordings refreshed every 30 seconds (the highest possible sampling rate). Prior to the first trawl of the night, the trawl eye and TDRs were attached within mesh bags at the center of the head rope. These sensors could be left attached to the net for up to four days before recharging. The wing sensors were attached at the intersection of the bridle and each wing. The wing sensors were attached at the beginning of each trawl and removed upon net retrieval so that the bridles could be spooled effectively. All of the ITI sensors were recharged after a period of approximately four days with the supplied battery chargers. In 2009 and 2011, a Furuno net sensor system was used to determine real-time headrope depth, although wing sensors were not available, so no spread information was obtained. In 2010 a Scanmar net sensor system was used with wing sensors. In 2012 a Simrad ITI system was again used, complete with wing sensors. In 2013-2015 a Marport net sensor system was used, however, spread sensors were not available. Some sort of real-time depth sensing system should be used during trawl deployments in order to properly maintain target headrope depth.

Ship’s speed is initially set at approximately 2 knots, speed through the water for trawl operations. The target amount of wire out can be adjusted based on the vessel used as 85 m is not always optimal. This can be done using the net senor gear and TDRs. Once initial wire out is determined, adjustments to the Ship’s speed are used to maintain target headrope depth, based on real-time net sensor data (e.g., ITI headrope depth real-time display). The net should fish at the target headrope depth or up to 5 m shallower. Fishing deeper than the target headrope depth is to be avoided (e.g. in areas where the bottom depth is shallow there is a risk of dragging the net on the bottom). Heavier weather may require adjusting the amount of trawl warp ahead of time as vessel speed may be more variable under such conditions.

Duration of trawl deployments

The standard duration for fishing the trawl net at the target headrope depths is 15 minutes. In areas of high jellyfish or salp concentrations, 5 minute “test” trawl deployments may be utilized to avoid potentially damaging the net. Fishing at target headrope depth begins when the designated amount of trawl warp is let out and the winch brake is set. All aft deck lights are turned off when the net is fishing at the target depth. Prior net deployment and retrieval times on the NOAA Ship DAVID STARR JORDAN averaged ~10 minutes for deployment and ~12 minutes for retrieval. Every effort should be made to deploy and retrieve the trawl net as quickly as possible (following all safety measures) to avoid possible interactions with marine mammals, which tend to aggregate at the surface.

Recording trawling operations information

The Ship’s Officer On Deck (OOD) or Survey Technician will record all pertinent trawling operations information into the marine operations. The following specific information is to be logged either electronically using the E-MOA via the Ship’s scientific computer system (SCS), or in written form:

Cruise Sequential haul number Trawl station number Date-time and location when net goes in the water Date-time and location when doors enter the water Date-time and location when net begins fishing at target depth Date-time and location when net haulback begins Date-time and location when doors exit the water Date-time and location when net is back on deck

Meters of wire out for the trawl warp Bottom depth Cloud cover Wind speed Wind direction Barometric pressure

In addition, the SCS aboard the ship shall log the following:

Sea surface temperature and salinity via the thermosalinograph (TSG) Sea surface fluorescence via the SCUFA All real-time net sensor data (e.g. Simrad ITI)

Handling the trawl net and the catch

The OOD and the Deck Department personnel shall be responsible for having the Ship on station and at trawling speed, and having the trawl winches operational for setting, fishing, and retrieving the trawl net. The Deck Department personnel will retrieve and spool the bridles and entire net, then shakedown the codend liner and open it into either a catch box on the deck, or containers provided by the scientific personnel. The codend liner will be shaken down thoroughly by the Deck Department personnel to ensure that all catch is removed from the net prior to the next trawl deployment. The Deck Department personnel will ensure that the V-doors and transfer cables are secured after each trawl and that the codend liner is secured. The scientific personnel are responsible for sorting, identification, enumeration and preservation of all samples collected.

Problems occurring during trawling operations

During periods of inclement weather, the Commanding Officer (CO) is ultimately responsible for the safety of the ship and personnel and therefore, he/she will decide when trawling operations are no longer safe after consultation with the Chief Scientist/Cruise Leader and the Chief Boatswain.

When problems are encountered during trawl operations the Chief Scientist/Cruise Leader is to be notified immediately. The following are examples of problems:

- The amount of time during the set and/or retrieval is too long

- unacceptable amounts of jellyfish in the catch

- gear damage or malfunction

- evidence of net contact with the bottom

- visible sunlight in the sky while the net is fishing at target headrope depth

- starting or ending position of trawl too far away from the standard trawl station position (> 2 nautical miles)

Mitigating interaction with protected species

30 minute, pre-set, protected species watch (monitoring prior to deploying trawl gear) Protected species (marine mammals, sea turtles, sea otters, short-tailed albatross, black-footed albatross, marbled murrelet) watches (visual observation) will be initiated by a designated person/s no less than 30 minutes prior to deployment of gear for sampling in order to determine if any protected species are near the proposed trawl set location. This watch can occur during transit leading up to arrival at the sampling station. If stations are less than 5 nautical miles apart (or less than a 30 minute transit time at typical transit speed) then pre-set watch should just last duration of transit. Upon arrival at a sampling station trawl operations shall be conducted immediately except when it is necessary to conduct a bongo plankton tow or CTD deployment prior to deploying trawl gear. Protected species watches will be conducted using any binocular or monocular sighting instrument, with a means to estimate distance to infringing protected species during daytime. During nighttime operations, visual observation shall be conducted using the naked eye and available vessel lighting.

Move-on rule If marine mammals, sea turtles or other protected species are sighted within 1 nautical mile (nm) of the planned set location prior to setting the gear, the vessel will transit to a different section of the sampling area to maintain a minimum distance of 1 nm between the set location and estimated location of sighted protected species. If, after moving on, protected species remain within the 1 nm exclusion zone, the CS or watch leader may decide to move again or to skip the station, but in any case may not set while a protected species is in the 1 nm exclusion radius. With regards to baleen whales, the CS or watch leader may use best professional judgment in determining whether moving on is warranted or no specific action is required.

Monitoring during trawl deployment, fishing and retrieval Also as part of the protected species watch, there will be a dedicated scientist on watch whenever the trawl is in the water (i.e., deployment, fishing, and retrieval). The scientist on watch will notify the Chief Scientist immediately if any protected species are observed within one nautical mile of the ship. If the trawl net is deployed (but not yet fishing) after an “all clear” visual scan and protected species are observed, then the gear will immediately be retrieved to avoid further interaction. The ship will then relocate to a distance one nautical mile away and the area will be scanned for any protected species presence. If the trawl net is fishing and protected species are observed, then the appropriate action should be taken based upon the individual circumstances with consultation between the scientists and CO/OOD (in some cases the net will be immediately retrieved, while in others it may be kept at depth to avoid protected species at the surface).

Data collection for visual watches All visual monitoring watches (30 min prior to set, deployment, fishing, and retrieval) and any data gathered during these watches will be recorded in the watch logs provided for each survey.

The scientific party requests the ship’s cooperation in implementing the scientist’s mitigation measures.

Every effort should be made to deploy and retrieve the trawl net as quickly as possible (following all safety measures) to avoid possible interactions with marine mammals, which tend to aggregate at the surface.

A further measure to mitigate marine mammal encounters is to install acoustic pingers on the trawl net. Two STM Products Dolphin Dissuasive Device (DDD 03) acoustic pingers will be attached to the trawl net whenever it is deployed to mitigate marine mammal encounters.

Reporting, Data Collection and Handling Procedures for Protected Species Interactions

All protected species (marine mammals, sea turtles, seabirds and fish) lethal and non-lethal interactions with fisheries research gear will be reported to the SWFSC Environmental Compliance Specialist through the Incidental Take Authorization (ITA) SWFSC.ITA@noaa.gov account. These interactions will be relayed to the SWFSC Director and recorded in the Protected Species Incidental Take Database within 48 hours of the event. In the event that protected seabirds are incidentally taken, either lethally or non-lethally, USFWS will be notified immediately for handling and disposition instructions (Weekdays: 541-867-4558, x. 237; Cell: 541-961-6904). If unable to reach USFWS, Progressive Animal Welfare Society (PAWS) 1-425-787-2500 will be contacted.

Catch of bull trout, eulachon and salmon will only be reported to SWFSC.ITA@noaa.gov at the conclusion of every survey day; no call is necessary. Appropriate communications on all authorized takes will occur in a timely manner to allow the ITA coordinator to report the event to the PSIT in the required 48 hours.

Lethal take of Marine Mammal or Sea Turtle If a lethal take of a marine mammal or sea turtle occurs, priority should be placed on removing animal from gear as quickly and safely as possible so photographs, measurements and biological samples can be taken according to protocol, PSIT-002.02, and then the animal should be wrapped in bag/s (trash bags or provided body bag) and placed in the scientific freezer. Concurrently, as stated above, the ITA coordinator should be notified immediately.

Non-lethal take of any protected species Priority for any non-lethal take is to release the animal as quickly as possible according to instructions below for its best chance of survival post-release. First and foremost, please take into consideration safety of all crew and staff. Concurrently, as stated above, the ITA coordinator should be notified immediately

Protected Species Handling In general, following a “common sense” approach to handling protected species will present the best chance of minimizing injury to the animal and of decreasing risks to scientists, officers and crew.

There are inherent safety concerns associated with handling/disentangling protected species, so using good judgment and ensuring human safety is paramount. SWFSC researchers should refer to PSIT- 004.02, SWFSC Marine Mammal Handling Guidelines, and the Pacific Islands Region's Identification, Handling and Release of Protected Species (PSIT-005.01), and SWFSC's marine mammal and sea turtle sampling protocol (PSIT-002.02) for more specific guidance on protected species handling and sampling (e.g., species identification, safe removal of fishing gear, etc.). For all protected species incidental interactions, SWFSC researchers will record interaction information using the Protected Species Incidental Take Database. The Marine Mammal and Sea Turtle Specimen Data forms should be filled out and for any incidental takes of seabirds or protected fish species (bull trout, salmon and eulachon) SWFSC researchers will fill out the Protected Fish and Seabird Specimen Data form.

Protected Species Sampling and Data Collection SWFSC scientists are authorized under MMPA regulation 50 CFR 216.22 and encouraged to collect samples from authorized protected species (see Table 1.) incidentally captured or killed during fisheries research activities. For sampling, follow guidelines in PSIT-002.02, SWFSC’s Detailed Sampling Protocol for Marine Mammal and Sea Turtle Incidental Takes and fill out the Marine Mammal and Sea Turtle Specimen Data form.

Trawl construction and repair

Midwater Trawl Description

The midwater trawl net is known as the modified California Department of Fish and Game “Anchovy” Net. It is also commonly referred to a the NMFS Modified Cobb Trawl. A

9.5 mm (3/8") fine mesh, knotless, white liner is inserted in the codend to retain small midwater organisms. The mesh liner is 7.6 m (25’) wide by 9.45 m (31') in circumference. The overall length of the entire net is 47 m (154’) and has a square mouth of 26.2 m (86’) per side. The net is constructed of nylon webbing and the mesh size (stretched) decreases from 152 mm (6”) in the wings and body to 38 mm (1.5”) in the codend. The codend is secured by a cowbell during tows.

A zipper is also sewn into the meshes above the liner in order to release large catches of jellyfish.

To open the net vertically, 42 floats 203 mm (8”) in size are attached to the headrope. 145 lbs. of

15.9 mm (5/8") chain is attached to the bottom of each wing and along the footrope. There is a 2 m (6.5’), 12.7 mm (0.5”) chain, setback extension to the footrope bridles. Total chain weight of 325 lbs. The bridles are V shaped with each section being 55 m (180’) long. The doors are

1.5 m x 2.1 m (5’ x 7') steel V doors manufactured by Net Systems, Inc. USA. Each door weighs approximately 830 lbs. We construct the trawl nets to the same standards each time one is built.

Following are plans for the net, liner, and doors and a trawl construction materials list.

Net plan

Codend liner plan

Door plan

Midwater trawl construction materials list

WEBBING:

Mesh sizes listed in the net plan are given in “stretched measure”, a standard method of measuring mesh size that includes the length of one knot, designated K.C.. Wings and body of trawl constructed of 152 mm (6”) #60T three strand nylon - dyed black or green.

CODEND LINER:

Liner #9843 – 9.5 mm (3/8") knotless mesh, 450 denier, 7.6 m (25') wide (forward to aft) by 9.45 m (31’) in circumference. The cylinder shaped liner is made in one rectangular piece 7.6 m x

9.45 m (25’ x 31 ‘) and sewn along one edge to create a uniform cylinder. White, or off-white in color, with larger black or green colored hanger meshes tied to the forward edge of the cylinder for attachment to the inside of the codend.

WIRE:

Originally used 6 x 19 Galvanized fiber core wire rope, eyes formed using galvanized reinforced thimbles. Switched to synthetic Dyneema line in 2016 (see following quote from L.F.S. Trawl).

ROPE:

Headrope/Footrope/Breastlines are all 9.5 mm (3/8") wire rope.

FLOATS:

Forty-Two 203 mm (8”) side lug or center hole trawl floats, equally spaced along headrope, 256 lbs. static lift.

RIBLINES:

15.9 mm (5/8”) Samson@ 2n1 stable braid, Dacron, light bonding. One link of 12.7 mm (1/2”) long link deck lashing chain is seized to the eye of the ribline and forward end (at wing tips) of ribline is equal to the length of the headrope/footrope/breastlines. Two thimbled eyes and chain link secured to the eye of the ribline are attached to the bridles using one 15.9 mm (5/8”) hammerlock. Riblines are measured with 400 lbs. of tension on rope.

FOOTROPE:

26.2 m (86’) of 9.5 mm (3/8") 6 x 19 galvanized fiber core wire rope (does not include the length of the thimbled eye at either end). 145 lbs. of chain is secured to the foot-rope along each wing tip, lashing every 6th link to the wrapped wire rope. Footrope extension of linked grade 80 deck lashing chain is connected to the footrope wing tip using a 15.9 mm (5/8”) hammer-lock. Overall length of footrope extension including hammerlock is 1.8 m (6’).

HEADROPE & BEASTLINES:

26.2 m (86’) ( not including length of thimbled eyes ) of 9.5 mm (3/8”) 6 x 19 galvanized fiber core wire rope. Wire is served with 9.5 mm (3/8”) three strand polypro rope.

BRIDLES:

TS2P 19 mm (3/4”) 55 m (180’) long, terminated.

DOOR LEGS:

TS2P 19 mm (3/4”) 16.76 m (55’) long, terminated.

TRANSFER CABLES:

TS2P 19 mm (3/4”) 22.86 m (75’) long, terminated.

DOORS:

Two 1.5 m x 2.1 m (5’ x 7') steel V doors, each weighing approximately 830 lbs. Manufactured by Net Systems Inc. USA specifically for NOAA NMFS in July of 1979, Door Serial Number is

892. Door tail chains of 12.7 mm (1/2”) long link chain are attached to the center hole of the two tail chain brackets using a 15.9 mm (5/8”) safety shackle. The upper of these chains is 2.6 m (8.5') long, and the lower is 2.6 m (8.5') long. They come together into a 15.9 mm (5/8”) hammerlock, to which the door leg is attached.

Trawl repair checklist

The Ship’s CO, Deck Department Chief and Deck Department personnel in collaboration with the Scientists will address all aspects of the trawl checklist prior to the cruise, and for repairs. Replacement netting and twine should be the same size and color. Knitted meshes should be the same size or larger, and knots pulled tight. Replacement ropes should be of the same material, be within 50.8 mm (2") of specified length, and should be replaced when outer cover is damaged. Checklist approved by Liam Massey of Pacific Trawl Company, Inc.

COMPONENT SPECIFICATION PORT STRBD

Bridles TS2P 55 m (180’) x 19 mm (3/4”)

Transfer cables TS2P 22.86 m (75’) x 19 mm (3/4”)

Door legs TS2P 16.76 m (55’) x 19 mm (3/4”)

Doors 1.5 m x 2.1 m (5’ x 7') V-door with G-hooks for transfer cables (NET Systems USA)

Simrad ITI sensors:

(Trawl eye) (Combo temp-depth) (Port spread) (Starboard spread)

Batteries charged, 2 bags near center of headrope and a bag on each wing at center of breastlines

Net panels correct meshes, no tears-holes-breaches*

Overall net length 47 m (154’)

Footrope 26.2 m (86’) x 9.5 mm (3/8”) wire rope with 290lbs of

15.9 mm (5/8”) chain and two 1.8 m (6’) 15.9 mm (5/8”) chain extensions

Headrope 26.2 m (86’) x 9.5 mm (3/8”) wire rope with 42 x 203 mm (8”) evenly spaced floats

Codend liner 9.5 mm (3/8”) fine mesh, clean, and attached in codend

Riblines 15.9 mm (5/8”) Samson 2n1 stable braid with robust lashings to the webbing**

Rigging:

Hammerlocks, G-Hooks, Flat Links, Swivels, Bow Locs, Thimble Eyes, Chain Links, Rigging Disks

Robust structural integrity and lack of significant corrosion

Appendix

Warp measurement on the NOAA Ship DAVID STARR JORDAN

The primary real-time measurement of trawl warps for the NOAA Ship DAVID STARR JORDAN’s two combo-winches was accomplished with electronic block wire counters, equipped with optical proximity counters, which enumerated the number of revolutions of the sheaves.

The system used the "Measurement Technology" LC-90 Series Instrumentation Display. The "Wire out" (Warp) was arrived at using a two channel quadrature proximity sensor arrangement, (counted pulses). These sensors were arranged to supply two (2) pulses to the display/computer for every "Target" that was sensed. The sequence in which these pulses arrive at the computer determined which direction to count, up or down. The computer counted these pulses then used the calibration constant to determine the amount of wire that had passed over the sheave. This information combined with time between pulses gave the speed. The system kept track of every pulse received and recalculated the wire out after every update. The trawl warp bends around the sheave before traveling up to the main deck and around the flag blocks. This system measured and displayed meters of wire out and wire tension. These displayed variables could be seen in the Ship’s Bridge, the aft labs, and in the winch booth. The Ship was responsible for annual calibrations of the electronic block counters.

A mechanical in-line wire meter (Olympic Model 1700, SN 2227) was also maintained aboard the NOAA Ship DAVID STARR JORDAN and was used to calibrate the electronic block counters when needed. This devise was portable and used as an additional independent method for measuring trawl warp. The wire to be measured entered through guide rollers, went across two lower flat faced rollers, through a wire guide, and out the other side. A precision milled, flat faced, roller rode on the cable with springs supplying the tension required to avoid slipping.

Excessive cable motion was compensated for by allowing some freedom of movement in the vertical direction. Motion along the cable axis (traveling) was prevented using securing lines, while motion in the cable cross axis was limited, but not prevented, by the mounting rod. The meter drive wheel was coupled to the mechanical meter through a coupled shaft, allowing the meter to be easily exchanged. The meter movement was then securely mounted to the drive wheel cheek plate housing. Thus the meter movement was directly coupled to the drive wheel.

Inside the meter movement, the drive shaft was coupled to the least significant digit wheel using precision gears. The gear ratio was such that one revolution of the drive wheel advanced this wheel by 1 digit. When this wheel went from 9 to 0 the next significant digit was advanced by 1 and so on down the line to the most significant digit. The reverse happened when the wire was retrieved. Because everything was mechanically coupled there was no calibration possible. Of course you do have to trust that the manufacturer gave the proper meter movement in the first place. The meter movement units were marked on the meter. This mechanical counter was a precision measuring, mechanically coupled device that required no calibration and little maintenance. The Ship was responsible for its maintenance.

Calibration of the NOAA Ship DAVID STARR JORDAN’s electronic block counter system

How to determine the calibration constant:

The NOAA Ship DAVID STARR JORDAN’s Chief ET previously determined mathematically, with a tape measure, the real circumference of the Ship’s sheaves where the wire actually rides.

You can't use anything in the specs because the actual circumference of the sheave where the wire rides is determined by the diameter of the wire and to some extent the angle of wrap.

The electronic block counter system’s computer basically wants to know how many consecutive sets of pulses will be received for every meter of wire that is let out.

Therefore, the Trawl and Combo winch sheaves are ~1.510 m around, where the wire rides.

Counts per meter (C/M) = number of targets per sheave rev * number of sheave rev per meter.

C/M = 2 * 1/1.510 C/M = 2 * 0.6622516 = 1.3245

The calibration constant should be 1.3245. Plug this number in the computer as the "Counts per Meter" entry.

Finally, the system needs to be fine tuned and the coefficients adjusted to remove the error factor caused by the Uncertainty Principle. This Uncertainty Principle and error factor are determined and adjusted for as follows:

STBD COMBO CONSTANTS PORT COMBO CONSTANTS CENT COMBO CONSTANTS

C/M = 1.273 C/M = 1.279 C/M = 1.279

TENSION COEFS= 3000 TENSION COEFS= 3000 TENSION COEF = 3000

ANGLE COEFS = 0 ANGLE COEFS = 0 ANGLE COEFS = 0

PORT HYDRO CONSTANTS STBD HYDRO CONSTANTS

C/M = 60.01 C/M = 3.0

TENSION COEFS= 4000 TENSION COEFS= 0

ANGLE COEFS = 36.5 ANGLE COEFS = 36.5

Wire out Calibration: This is easiest, and more accurate, if done while underway.

1. Use the method below to determine the beginning coefficient then verify the accuracy by spooling wire with the mechanical cable counter (Olympic Model 1700, SN 2227), mounted to the wire.

2. Check the sheaves of the trawl system and the wheel on the mechanical counter for ease of rotation and flag block for freedom of movement. The stiffer either is the more likely the chance you will spend your allocated time in an exercise in futility. This procedure will work if the system is properly prepared.

3. Insure you have enough water depth to avoid bottom contact.

4. Insure that you have enough weight on the line to prevent slippage on the sheave and/or the mechanical counter wheel. You can deploy wire until the weight of the wire is sufficient.

Do not pay the wire out at an excessive rate. Excessive speed will result in errors, due to wire slippage, and/or damage to the mechanical counter. Experience has shown that if you start at 20 m/minute and increase to 50 m/minute after 100 m the wire tension is sufficient to prevent slippage and the counter is not stressed. Sea state also plays a part in how fast the wire can be let out. In this case “slower is better”.

5. Thread the wire through the blocks. The mechanical counter has been modified to allow mounting without the need to thread through the guides.

6. Secure the counter by having 2 people hold it down, so as to not allow up and down movement of the entire counter frame while avoiding excessive side-to-side movement. The counting wheel is spring loaded to maintain constant pressure on the wire however the less the wheel has to move the better.

7. Mark the wire with paint where it exits the mechanical counter. This gives you a reference point and might come in handy at a later date, if the paint doesn’t wear off. Do not make multiple calibration marks on the cable at this time. If you blow the calibration the first time through, this just confuses the issue.

8. Payout a minimum of 250 m in order to get a reasonable calibration. During payout stop at 50 m points (50 m, 100 m, 150 m, 200 m, 250 m) to adjust the coefficient so as to cause the electronic meter indication to agree with the mechanical counter. Insure there is no slippage

9. Retrieve the wire. When your reference mark returns to where it started both counters should read zero (0). If not, be glad you didn’t make multiple marks, and repeat the process until it does.

10. When you finally get a coefficient that results in getting the same amount of wire back as you deployed and the counters agree on the amount of wire out, you need to deploy one more time to confirm the system is properly calibrated.

During this deployment you could stop and mark the wire in increments that will best suit the wire usage.

Hints:

If, at the 100 m stopping point, you need to increase the coefficient by a significant amount and when you get to 250 m point the coefficient needs to be decreased significantly, then you have “probably” had wire slippage over the sheave during the first 100 m or so. You probably should correct the problem and start over.

Probable cause(s): Insufficient cable tension during the initial 100 m or so.

Check: 1. Do you have enough weight?

2. Does the sheave turn freely?

3. Is the wire rubbing the sides of the Sheave groove excessively? Caused when the sheave cannot swing freely as the wire travels across the face of the drum.

Combo Winches Sheave size = 1.510 (in theory).

STBD Hydro winch Sheave size = .590 (in theory).

COMBO winches and STBD HYDRO winch:

C/M = number of targets per sheave rev x number of sheave rev/meter.

COMBO Number of targets = 2 Sheave revs/Meter = 1/sheave circumference = 1/1.510 = .6622517 C/M = 2 x .6622517 = 1.3245

Use the same formula for each winch.