Northeast Fisheries Science Center
Oceanography Branch

Environmental Monitors on Lobster Traps



eMOLT Phase VI: Bottom Currents

After a few years of deploying surface drifters in the Gulf of Maine, we started to think about the deeper, near-bottom currents. Since conventional instrumentation was cost prohibitive and often difficult to use (given the biofouling that occurs in our waters), we needed to devise a simple, less expensive means of monitoring the flow. A new method suggested itself when the small inclinometers came on the market. Could we secure a buoyant length of PVC pipe to the ocean bottom, attach one of these $69 tilt meters, and infer the flow?

Given the issue at that time associated with potential whale entanglements in lobster gear and the uncertainty of whether sinking groundline is actually needed in some regions, we finally proposed in 2007 to develop this low-cost method of monitoring the bottom currents from lobster gear. As many lobstermen have suggested, the existing groundlines may often lay down on the seafloor given strong currents in certain areas. While some work was currently underway to examine the degree to which groundline is dragged down, little is known about the spatial and temporal variability of bottom currents in these areas. As of this writing, we have tested and validated this idea and compared the results with traditional current meters. It has worked exceedingly well.


Beginning in the early summer of 2008, initial deployments were made by Vitalii Sheremet (lead developer) within the Woods Hole Oceanographic Institute’s instrument test-well where tidal currents provide sufficiently-detectable observations.Deployments of more traditional instrumentation were also be made (alongside for comparisons) including two current meters: the Sontek Aquadopp owned by URI and the Nortek Vector owned by NEFSC (see comparison in figure above).

After these initial multi-day deployments in Woods Hole, we transferred the equipment to 10 local lobstermen working along the New England coast.These individuals have tested eMOLT equipment for us in the past. This deployment was conducted over multiple weeks in an attempt to detect variations due to storms and lunar periods. While the analysis of these records are under way, an example result is pictured below and links to other plots (as they are generated) are linked from Table 1 below.

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Given the recent advances towards a nation-wide ocean observing system, the idea is ripe. New England lobstermen now have an opportunity to make a significant contribution to the integrated system on the Northeast Continental Shelf by securing an unprecedented array of relatively inexpensive sensors on the seafloor. While the momentum is growing to build a large scale integrated system, the funding is so far limited to existing infrastructure. Until money is available to fund new initiatives, we are forced to take small steps with low-cost alternatives. These small steps will, at least, provide some form of background data in the intervening years and provide a system to gradually build in the future.

Much of our previous eMOLT work involved developing a network of participants. While this outreach work (building relationships with fishermen) will certainly continue, we hope to now focus the majority of our effort in providing useful products in the form of web-served information. The results of our 2008 and 2010 pilot studies are posted in Table 1. The figures below depict the slight change in phototype with 2008 and 2010 on the left and right, respectively. In the case of 2010, a secondary sensor is shown attached to the base in order to monitor the orientation of the trap itself and potentially document the trap orientation.


While the intial deployment in 2008 showed traps on their side or upside down nearly 25% of the time, the 2010 results reduce that percentage to only 6% of the time. There were only a few cases in 2010 where the trap WAS more than 45 degrees from level for greater than 25% of the time.

In some cases, where the tidal current is particularly strong or perhaps the groundline was overly taught, the trap was flipping on its side. In one month-long deployment in 86 meters, this happened a dozen times. See zoomed-in figure below. It also happened in deep (274 meter) water near the Hudson Canyon.

A few dozen deployments were made in 2011 and all but one instrument returned good data. Links to all the plots made for individual deployments as provided in the tables below associated with each year.

Table 1. 2008 Results

sn1 sn2

("major-axis" velocity)

fname

(zoomed-in plot)

lname

("minor-axis" velocity)

Location

(zoomed-in plot)

lat

(model comparison)

lon

(direction)

w_depth(m)

(w/Portland Tides dh/dt)

GMT_starttime

(low-passed vs model)

GMT_endtime

(stickplot example)

comments
2 2039122 Alex Brown Truro, Ma bayside 4202.56 7011.29 4.6 24-Sep-2008:013:00 03-Nov-2008:16:30 no temp
3 2039123 Dave Casoni North of Cape Cod Canal 4146.44 7028.86 11.0 24-Sep-2008:011:00 27-Oct-2008 02:33:17 Broke but good record w/temp; noted difficulty aligning bolts
4 2039124 Bob Marcella off Hull, Ma 4218.18 7048.00 23.7 09-Oct-2008 18:20:54 27-Oct-2008 02:33:17 MASS DMF coordinated study
5 2039028 Bill Doherty outside Boston Harbor 4219.88 7052.41 19.8 27-Sep-2008 00:41:48 27-Oct-2008 02:33:17
6 2223026 Brad Parady off York Maine 4304.25
7036.82
24.9 06-Oct-2008 14:28:38 27-Oct-2008 02:33:17 low velocity; most damage to tubing
7 2230127 Brian Tarbox Casco Bay 4339.07 7013.42 7.0 26-Sep-2008 23:36:46 03-Oct-2008 04:06:11 Undisturbed for 1 month. Probably, the cage landed on its side, after 6 days it apparently flipped upside-down such that the instrument stuck under the lobster pot.
8 2223018 Elliot Thomas Casco Bay 4342.19 7009.94 21.9 26-Sep-2008 23:36:46 17-Oct-2008 13:51:29
9 2223019 Jason Day off Vinalhaven Maine 4401.66 6851.33 9.1 02-Oct-2008:013:00 02-Nov-2008:013:40 he noted seiche on 27 Oct +/- 1 day but instrument was apparently lying on its side (failed?)
10 2223020
Mike Dassatt Penobscot Bay 4422.10
6849.17

???? 27-Oct-2008 01:28:15
11 2039121
Jim/Reaz Manning/Kahn NEFSC Dock 4132.0
7041.4

31-Jul-2009 10:00:00 05-Aug-2009 08:05:00 Included all three: Nortek, Onset, and StarOddi deployments

Table 2. 2010 Results

sn

("major-axis" velocity)

fname

(zoomed-in plot)

lname

("minor-axis" velocity)

Location

(zoomed-in plot)

lat

(model comparison)

lon

(direction)

w_depth(m)

GMT_starttime

(low-passed vs model)

GMT_endtime

(stickplot example)

comments
9672596
Billy Souza BS02 4203.75
7003.31

13-Oct-2010 19-Oct-2010
9777031
Pat White PW01 4307.89
7037.04

02-Oct-2010 19-Oct-2010
9672592Alley, Ricky, RA014415.106811.5029.3,2010-10-03 15:30:002010-11-30 13:12:009762268
9672593Anderson, Billy, BA024440.256702.186.0,2010-11-13 15:00:002010-12-12 00:00:009672621
9672612Carver, Dick, DC014400.396902.3714.6,2010-10-13 11:17:002010-12-11 00:35:009672597
9672616Casoni, Dave, AC024148.877027.6119.6,2010-10-11 12:43:122010-11-20 12:28:489762287
9762266Chioffi, Lucas, LC014345.216919.6436.6,2010-10-20 11:02:242010-12-10 19:40:489672599
9762271Chipman, JohnSr, JC024409.536757.1077.7 2010-10-29 12:00:002010-12-10 13:55:129672604
9762274Colbert, Bob, MJ014011.106827.00301.82010-10-11 00:40:192010-12-11 00:28:489762269
9762281Dassett, Mike, MD014423.506857.2044.3,2010-10-12 14:25:002010-11-03 14:50:009672608
9762288Doherty, Bill, BD014219.907052.4020.1,2010-10-02 16:04:482010-12-03 12:44:389672617
9762289Drouin, John, OD044427.816730.9840.2,2010-10-05 16:49:262010-11-30 16:04:489762275
9762293Faulkingham,Mike, MF034413.206803.0373.2,2010-10-11 11:24:002010-11-29 16:55:129672614
9762296Fernald, Bruce, BF014407.606809.5054.9,2010-10-11 16:26:242010-11-23 14:19:409672619
9762298Flanigan, Peter, PF014259.927025.3098.8,2010-10-19 12:24:282010-12-10 12:24:289776994
9776990Johnson, David, DJ044324.717010.1395.1,2010-10-19 17:15:212010-12-09 18:14:249762278
9777032Lemieux, Norbert,NL024440.686657.23106.12010-10-26 19:55:002010-12-12 00:00:009762292
9777028Martin, Kurt, KM054139.586946.07 53.02010-10-20 18:45:002010-11-19 17:45:009672615
9776991Mason, Phil, PM044210.007032.0045.7,2010-10-08 17:45:362010-12-10 14:44:099672600
9776993NuddJr, Bobby, BN014254.587042.2236.6,2010-10-09 12:14:242010-12-05 15:36:009762286
9777009Marchetti, Mike, MM014112.837114.1143.9,2010-10-10 13:30:432010-12-11 00:34:339762297
9777000Palombo, Marc, TA144005.356851.70237.72010-10-19 14:31:122010-11-30 17:45:369762285
9777002Peabody, John, JP223933.737228.63274 2010-10-08 05:00:002010-12-12 00:00:009672590Moved 11/3 to JP13
9777003Philbrook, Clayton,CP014347.386851.9378.6,2010-10-12 12:15:002010-12-12 00:00:009762267
9777011Sauvageau, Therese,TS014229.807047.3427.4,2010-10-09 12:21:362010-12-10 13:45:079762276
9777014Smith, Jay, SJ024342.756850.3369.5,2010-10-19 19:35:022010-11-29 20:09:369762264
9777019Tarbox, Brian, BT034339.087013.4211.0,2010-10-07 13:26:242010-11-18 16:27:509672620
9777022Tripp, Jim, JT044346.306840.20115.22010-10-13 16:00:002010-12-12 00:00:009762294
9777024Wells, Mark, MW034347.886952.62 41.22010-11-02 14:55:002010-12-12 00:00:009776998
9777031White, Pat, PW014307.897037.04 12.82010-11-02 12:48:002011-04-30 18:12:00

Table 3. 2011 Results

idTilt_snLast_nameFirst_nameSiteLatLonMetersStartEndBase_sn
19762280AlbertsJeffJA024156.406955.20 272011-08-21 21:152011-09-15 20:459762282
29672592AlleyRickyRA014415.106811.50 292011-08-05 15:152011-08-30 14:459762268
39672606BrownAlexAB014202.217,007.88 182011-07-04 18:152011-07-29 17:459672613
49672609CarterJonCJ014422.776807.23 462011-06-07 12:152011-07-02 11:459777025
59672612CarverDickDC014400.396902.37 152011-09-29 20:152011-10-24 19:459672597
69672616CasoniDaveAC024148.877,027.61 202011-08-24 14:152011-09-18 13:459762287
79762271ChipmanJohnSrJC024409.536757.10 782011-10-16 15:152011-11-10 14:459672604
89762288DohertyBillBD014219.907,052.40 202011-09-25 18:152011-10-20 17:459672617
99762289DrouinJohnOD044427.816730.98 532011-09-16 18:152011-10-11 17:459762275
109762296FernaldBruceBF014407.606809.50 552011-09-04 18:152011-09-29 17:459672619
119762298FlaniganPeterPF014259.927,025.30 992011-08-17 12:152011-09-11 11:459776994
129777009MarchettiMikeMM014112.837,114.11 442011-09-15 14:152011-10-10 13:459762297
139777007MelquistSrJohnOM044349.956856.8 332011-09-15 13:152011-10-10 12:459777012
149777017MoodyTomHM014350.886933.30 62011-09-12 19:152011-10-07 18:459722290
159777000PalomboMarcTA144057.006845.00 1282011-10-03 21:152011-10-28 20:459762285
169777002PeabodyJohnJP193,937.207,207.10 1522011-09-09 18:152011-10-04 17:459672590
179777014SmithJaySJ024342.756850.33 692011-09-17 15:152011-10-12 14:459762264
189777015SouzaBillyBS024203.757,003.31 272011-09-09 13:152011-10-04 12:459672596
199777019TarboxBrianBT014345.877,005.86 112011-10-02 19:152011-10-27 18:459672620
209776991WhitePatPW014307.897,037.04 132011-08-22 21:152011-09-16 20:459672600



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For further information contact: 508-495-2211 or  James.Manning@noaa.gov

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