Successful Last Deployment of Pioneer Array on NE Shelf

The Pioneer 18 Array team and crew of the R/V Neil Armstrong pulled into the dock at Woods Hole, MA, on April 27, a day earlier than expected, having completed all objectives of the expedition. Their mission included the last deployment of the Pioneer Array at its current location on the New England Shelf. The Pioneer Array components now in the water will be recovered in November 2022 and redeployed in the Southern Mid-Atlantic Bight in the Spring of 2024.

The expedition consisted of two legs. On leg #1, three Coastal Surface Moorings and multiple gliders were recovered and deployed and autonomous vehicle missions were completed. On leg #2, the team deployed five Coastal Profiler Moorings. Three Coastal Surface Moorings and seven Coastal Profiler Moorings were recovered, two of which could not be recovered during an earlier expedition because of weather conditions. The recovered equipment will be taken apart, refurbished, and in some cases, reconfigured for deployment at the new location.

Weather conditions allowed for multiple deployments of a remotely operated vehicle, to help assess the condition and assist in the recovery of mooring components that could not be recovered by standard techniques (using an acoustically-triggered release). The team also conducted additional activities that ranged from water sampling adjacent to the moorings to cross-shelf CTD (connectivity, temperature, and depth) surveys in the vicinity of the moored array, and surveys using shipboard sensors. A variety of ancillary activities, accommodating eight participants from five different institutions, were also facilitated during the cruise.

Al Plueddemann, Principal Investigator of the Coastal and Global Scale Nodes (CGSN) and Chief Scientist of Pioneer 18 said, “The successful completion of this expedition again demonstrates the capabilities and experience of the CGSN team and the R/V Armstrong, and bodes well for successful operation of the Pioneer Array in its new location in the Southern Mid-Atlantic Bight.”

[media-caption path="/wp-content/uploads/2022/05/last_NES_CPM_PMUI-17-copy.jpg" link="#"]The Coastal Profiler Mooring shown here, PMUI-17, will be the last Pioneer mooring deployed on the New England Shelf. After providing data through the summer and early fall, the current array will be recovered in November of 2022 and relocated to the Southern Mid-Atlantic Bight in 2024. Credit: Jess Kozik©WHOI.[/media-caption]

The Pioneer Array was originally commissioned in 2016 as a re-locatable coastal array suitable for moderate to high wind, wave and current regimes on the continental shelf and upper slope. The new location in the Southern Mid-Atlantic Bight was decided upon after a series of workshops in 2021, co-sponsored by the National Science Foundation and the Ocean Observatories Initiative Facility Board, to gain community input on a new location that would best address pressing science questions.

Plueddemann added, “The Pioneer Array has collected a remarkable data set from the New England Shelf, which scientists will continue to use to understand frontal dynamics and related ecosystem impacts in this important and dynamic region.”

[media-caption path="/wp-content/uploads/2022/05/heads_up-copy.jpg" link="#"]When the large Coastal Surface Mooring buoys are recovered everyone pays close attention. The buoy tower spins when the hull is picked out of the water, and the deck team needs to be ready with a snap hook to clip into the circular rails on the tower top and arrest the motion. Credit: Andrew Reed ©WHOI.[/media-caption]

As the Pioneer 18 team headed home, another CGSN expedition is about to hit the water. A team of scientists and engineers is already traveling to Seward, Alaska to mobilize for another OOI expedition. On May 12, they will be aboard the R/V Sikuliaq for a 19-day expedition to the Global Station Papa Array, in the Gulf of Alaska, about 620 nautical miles offshore. This team will deploy five moorings — three for OOI and one each for the National Oceanic and Atmospheric Administration and the University of Washington. Once on site, the team will first deploy the moorings onboard, then recover those that have been in the water for a year. Upon completion, the ship will transit to the demobilization port of Seattle, Washington. Bookmark this site, and follow along on their progress.

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Ride Along with Pioneer 18

Here’s an opportunity to travel along with the team of sixteen scientists and engineers as they conduct a bi-annual recovery and deployment of ocean observing equipment at the Coastal Pioneer Array.  This is the 18th “turn” of the equipment since the observatory was put in place in 2015. The data collected has advanced understanding of the shelf/slope dynamics and impacts on ecosystems.  Bookmark this page to follow along on the expedition, which runs through the end of April.

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18th Turn of the Pioneer Array in April

Sixteen science party members will be on board the R/V Neil Armstrong during April for each of two legs comprising the eighteenth turn of the Pioneer Array, where moorings are recovered and new ones deployed. This April cruise will be extremely busy, with 32 overall objectives, as well as other ancillary operations.  Pioneer 18 is the first cruise since 2020, when COVID-19 protocols were implemented, to support a larger science party to conduct ancillary activities.

The cruise plan calls for deployment of eight moorings and three gliders and recovery of 10 moorings. Autonomous underwater vehicle (AUV) missions will be conducted in the vicinity of the moored array, providing additional ocean observing measurements. CTD casts and water sampling will be done in conjunction with deployment/recovery operations and ship vs. buoy meteorological comparisons will be made at each Coastal Surface Mooring site.

[media-caption path="/wp-content/uploads/2022/03/DSC0507.jpg" link="#"]During Pioneer 18, ten moorings will be recovered. Once close to the ship, crew members grab the moorings with a hook, and direct them to the stern of the ship to be brought onboard. Credit: Darlene Trew Crist ©WHOI.[/media-caption]

“We are pleased to be approaching full capability for Pioneer 18 after multiple cruises with COVID-related restrictions,” said Al Plueddemann, chief scientist for Pioneer 18 and lead for the Ocean Observatories Initiative Coastal and Global Scale Node of which the Pioneer Array is part. “There is a lot to accomplish over our 21 days at sea, and having the opportunity again to bring collaborating scientists onboard will make full use of the ship and our time at sea.”

On Leg 1, Scientists Mei Sato of Woods Hole Oceanographic Institution (WHOI) will join Pioneer 18 to conduct zooplankton sonar testing, Peter Duley of the National Oceanic and Atmospheric Administration will conduct Marine Mammal Observations, and a student from the University of Rhode Island will oversee a glider deployment. Additionally, unattended underway sampling will be conducted in support of the Northeast U.S. Shelf (NES) Long-Term Ecological Research (LTER) project on Leg 1. On Leg 2, NES-LTER efforts will increase, with four participants (two from WHOI and two from the University of Rhode Island) onboard to conduct activities that include CTD and ring net casts and incubations, as well as continuing unattended underway sampling.

[media-caption path="/wp-content/uploads/2022/03/IMG_6146.jpeg" link="#"]Plans are to deploy three gliders that will collect data in the water column between the Pioneer moorings for the next sixth months. Credit: Darlene Trew Crist ©WHOI.[/media-caption]

Weather conditions and time constraints during the Pioneer 17 cruise precluded complete recovery of the Offshore and Upstream Offshore Profiler Moorings. Additional objectives for Pioneer 18, to be conducted if time and conditions permit, include completing the recovery of these two moorings, as well as several anchor recoveries using a remotely operated vehicle (ROV), glider tests, and surveys in the vicinity of the Pioneer moored array using shipboard systems (CTD, ADCP, EK-80).

“We have a very ambitious agenda for Pioneer-18, but our team is experienced and well-equipped to complete this large list of tasks ,” added Plueddemann. “We just need a good weather window to get the job done.”

Pioneer 18 team members will be sharing their progress during the month of April.  Bookmark this page and follow along.





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Initiation of a Marine Heat Wave

Marine heat waves are sustained, anomalous ocean warming events with significant regional extent.  In some cases, these heat waves are driven by heating from the atmosphere.  In new work (Chen et al. 2022), it is shown that ocean processes can also be responsible for marine heat waves.  In this case, the presence of anomalously high temperatures on the New England shelf was detected by CTD observations made by commercial fishing vessels.  The fishing vessel CTD data indicated that the heat wave was a “compound event”, i.e. one with large anomalies in both temperature and salinity.  Because atmospheric heating would drive only a temperature anomaly, and because the Gulf Stream derived slope water offshore of the New England shelf is high in both temperature and salinity, it was surmised that this heat wave was driven by ocean advection.

[media-caption path="/wp-content/uploads/2022/02/CGSN1.png" link="#"]Figure 23. Salinity contoured vs. depth and time for the Pioneer Upstream Inshore (PMUI) and Central Inshore (PMCI) profiler moorings from November 2016 to February 2017. The 34.5 isohaline is marked in black to highlight the boundary between the shelf and slope waters.[/media-caption]

The authors used data from Pioneer Array profiler moorings (PMUI and PMCI) to support this ocean advection hypothesis.  Salinity records (Figure 23) show high salinity events in Nov/Dec 2016 and Jan 2017.  The salinity anomalies are indicative of slope water (S > 34.5), are most intense at the bottom, and are more pronounced further offshore.  This is consistent with a bottom intensified intrusion of warm, salty slope water onto the shelf to initiate the heat wave observed by the fishing fleet CTDs in January of 2017.

Further investigation was done to understand the cross-shelf exchange process, which presumably originated at the shelfbreak and penetrated large distances onshore as a bottom intrusion.  The principal tool for the additional analysis was a new high-resolution regional model.  The model was able to reproduce major features including shelf water properties, the shelf break front, and warm-core rings in the slope sea .  Critically, the model showed the presence of cyclonic eddies (opposite in rotation, thinner and smaller than the warm core rings) that were responsible for driving cross-shelf flow and intensifying the front.  The authors argue that these processes precondition the outer shelf by bringing warm salty water to the shelf break, i.e. roughly the 100 m isobath.

Another step is necessary to produce the dramatic, bottom intensified intrusion of warm salty water to ~50 m depth, as seen in January 2017.  Further examination of the model, including runs with and without wind forcing, indicated that persistent upwelling-favorable winds along with topographic effects were the additional ingredients necessary to cause the dramatic intrusion.  Although some onshore penetration results from the standard “two-dimensional” wind-driven upwelling, the authors found that details of the three-dimensional regional topography were critical to extensive slope water penetration in the form of a warm, salty, bottom-intensified tongue.

Identifying the unusually strong intrusion and finding the hints to a slope-sea origin shows the importance of sustained observing, in this case from both the Pioneer Array and the fishing fleet.

Unraveling this remarkable, multi-step process, with pre-conditioning by small-scale cyclonic eddies followed by a topographically-controlled, wind driven response, is a testament to the power of high-resolution models to fill in dynamical gaps in the observing systems.  The authors note that “this study provides dynamical explanations of the observed water mass anomalies across the shelf, offers new insights about cross-shelf exchange…  and lays the ground work for future studies.”


Chen, K., Gawarkiewicz, G., & Yang, J. (2022). Mesoscale and submesoscale shelf-ocean exchanges initialize an advective Marine Heatwave. Journal of Geophysical Research: Oceans, 127, e2021JC017927.

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Fishers and OOI Scientists Working Together to Advance Science

An article in the Cape Cod Commercial Fishermen’s Alliance newsletter highlighted the work between its members and scientists at Woods Hole Oceanographic Institution (WHOI), using OOI Pioneer Array data.  The collaboration resulted in discovery of …“ all these things happening on the New England Shelf that we didn’t anticipate,” said Al Plueddemann, a senior scientist in physical oceanography at WHOI.

An important change in recent years is an increase in the meandering or “wiggliness” of the Gulf Stream. In addition the Gulf Stream has been generating more “Warm Core Rings,” large clockwise eddies.

Read more about how the collaboration is advancing science here.

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Tracking Fish with Acoustics

New RAFOS Ocean Acoustic Monitoring (ROAM) tags have recently been designed to allow geolocation of underwater assets, including pelagic fishes, over large areas in the ocean and even deep into the ocean’s twilight zone.

[caption id="attachment_22879" align="alignleft" width="350"] The ROAM tag is small (30 mm x 10 mm) and light enough (8 gm in water) to be attached to an ocean glider with no adverse impacts on performance. Here are two ROAM tags attached to OOI test glider 363 before deployment from the R/V Armstrong during the Pioneer 17 cruise. Credit: ©WHOI, Diana Wickman.[/caption]

An opportunity to test the new ROAM tags arose in conjunction with the October 2021 Pioneer Array mooring service cruise. “We had recently deployed moored sound sources in deep water between Cape Cod and Bermuda,” said Simon Thorrold who, with University of Rhode Island colleagues Melissa Omand and Godi Fischer, is leading the ROAM fish tag development. “One of our goals was to determine whether tagged fish near the continental slope south of New England could be detected using these distant sources.” Thorrold reached out to the OOI team to see if there was potential for a short-term test at the Pioneer Array site, located 75 nautical miles south of Martha’s Vineyard at the shelf-slope interface.

OOI Project Scientist Al Plueddemann and the OOI glider team determined that a glider test planned during the mooring service cruise in late October would be happening at the right place and the right time to be useful for testing the acoustic tags. “This technology is something we would like to consider for OOI, and in particular for the Pioneer Array in its new southern Mid- Atlantic Bight location,” said Plueddemann, “so the potential for a test was of interest to us.”

The glider team determined that the small (30×10 mm), light (8 gm in water) tags would have no measurable impact on glider performance and could be safely accommodated on the test glider. The tags were mounted to the glider by fitting the tags into plastic loop clamps and then securing the loop clamps to existing threaded holes in the glider hull. During the three-day test deployment, the glider made one dive to 50m, one dive to 200m, three dives to 500m, and approximately 76 dives to 200m.

The glider data and acoustic tag data are being evaluated, and will provide information about fish tag performance and the potential for future use within the OOI arrays.

This article was written by Woods Hole Oceanographic Institution colleagues: Senior Scientist Simon Thorrold and Senior Engineering Assistant II Diana Wickman.

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OOI’s Contributions to Understanding the Changing Ocean Cited in Boston Globe

Woods Hole Oceanographic Institution Research Scientist Glen Gawarkiewicz cites how he uses OOI data to figure out what is happening in the changing ocean in an article on that appeared on the front page of the Boston Globe on December 28, 2021.

In a record-breaking year of weather, signs of a changed world.

[caption id="attachment_22801" align="alignnone" width="1610"] A resident walked through floodwaters left by Hurricane Ida in La Place Louisiana on August 30, 2921. Credit: Luke Sharrett/Bloomberg via the Boston Globe.[/caption] Read More

Gulf Stream Species in Cold North Waters Spur Scientific Discovery

In early 2017, something strange was going on in the waters off the coast of Rhode Island.  Fishers were pulling up a very unusual bycatch of Gulf Stream flounder and juvenile Black Sea bass. The Gulf Stream flounder are typically found in warmer waters, and while black sea bass are a very common fish, they are typically not present in cold water in the middle of winter, particularly not their juveniles. The fish coming up in their nets were so unusual for this time of the year, that a member of the Commercial Fisheries Research Foundation (CFRF) sent a photograph to Woods Hole Oceanographic Institution (WHOI) scientist Glen Gawarkiewicz asking what he thought might be causing these tropical fish to end up in cold New England waters in the dead of winter.

[media-caption path="/wp-content/uploads/2021/12/KIMG0396-2.jpg" link="#"]Anna Mercer from CFRF sent this photo of Gulf Stream flounder and juvenile Black Sea Bass to Glen Gawarkiewicz, launching an investigation that resulted in three research papers.[/media-caption]

“One fun thing about my relationship with the fishing community now is if they see unusual things, they send them to me. And then I’ll usually go right to the Pioneer Array website,  look at the data and see if there’s some kind of a story, I can tell about the oceanographic conditions that might have given rise to unusual features, or unusual fish,” said Gawarkiewicz.

This query about an unusual catch prompted a scientific investigation whose results were recently published in the Journal of Geophysical Research: Oceans. The authors, WHOI colleagues Ke Chen, Glen Gawarkiewicz, and Jiayan Yang, identified for the first time the cause and multi-faceted dynamics at play in a subsurface marine heat wave (a high temperature anomaly event), expanding views of contributing factors to such ocean-altering events. They pinpointed the interplay between smaller scale cyclonic eddies and warm water intrusions that created an anomalous marine heat wave.

The research team started with the traditional hypothesis that warm core rings at the shelf break were pushing warm and salty water onto the shelf towards shore, generating a marine heat wave. But  after analyzing the fishing data and oceanographic data from the Pioneer Array, the team was not able to pinpoint the exact process causing the marine heat wave.  Chen took up the challenge and created a numerical model simulating ocean conditions during November 2016-February 2017.

The model, which was at an exceptionally fine scale of 1 kilometer resolution, captured what the team saw from the data. The model revealed warm core rings were not solely responsible for the increase in temperature of water moving into shore, but rather the heated, salty water was being moved by a combination of previously overlooked smaller scale cyclone-like eddies (circular currents of water) in the periphery of the warm core ring. The model also revealed a very persistent wind blowing from west to east in late January 2017 that worked jointly with the cyclonic eddies that had already changed the outer shelf conditions.

The winds brought the warm and salty water from the shelf break to around 50 meters depth for a distance larger than 100 kilometers over five-six days. The intrusion was localized. It moved along the slope,  climbed up the shelf, and moved onshore.

“So this remarkable intrusion was really different from what has been known of the dynamics contributing to onshore intrusions for this region, “explained Chen. “It is a very new and exciting finding that such intrusions can be a combination of smaller scale eddies and wind causing warm water intrusions at a particular location.”  The model shows the complexity of such intrusions that may result from multiple sources and conditions.  “It provides a more complete picture of conditions and how they might ultimately impact what fish are caught and where they are caught,” added Chen.

Gawarkiewicz concluded, “The Pioneer Array has just worked wonders for our relationship with the fishing industry and has also allowed us to see ongoing changes in this ocean region that keep accelerating.  The Pioneer Array just brilliantly combines both the cutting-edge research, like the modeling Ke is doing, with the real dire societal need of identifying and ultimately understanding changing ocean conditions. I only wish that we could have a Pioneer Array, basically in every region of the country.”


See Boston Globe article on December 28, 2021 for other ways OOI data are contributing to scientific understanding of the changing ocean.


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New Controller Latest in OOI Innovations

Having equipment in the water around the clock for six months at a time provides many challenges for the land-based OOI engineering team charged with keeping the equipment operational so there is a continual flow of data to shore. Maintaining consistent, reliable power for the ocean observing equipment is at the top of this list of challenges.

OOI’s data-collecting instruments attached to the moorings run on batteries charged by renewable wind and solar energy. OOI is in the process of replacing the current solar panels with new panels that are more efficient at generating energy, even when shaded. To supplement this upgrade, the OOI arrays are also being outfitted with a brand-new solar controller to manage the energy going into the batteries. Like with the new solar panels, OOI engineers looked for a controller that was available commercially for easier repair and replacement.

“What was important to us was finding a way to use these new solar panels in the best, most optimal way,” said Woods Hole Oceanographic Institution (WHOI) engineer Marshall Swartz. “We looked for a company that would help us specify and build a customized algorithm for a controller that would optimize the functionality of the panels by taking into account battery temperatures.”

[media-caption path="/wp-content/uploads/2021/12/DSC0486-2.jpeg" link="#"]Buoys get quite the workout when they are in the water for six months and more. Powered by wind, solar, and batteries, OOI has recently improved the way energy from the solar panels is managed with new controllers.  Credit: ©WHOI, Darlene Trew Crist. [/media-caption]

Some larger, older controllers can consume up to 3-5% of the energy coming into the device, but the new controller is smaller and more efficient, helping to optimize the amount of energy harvested.

Temperature conditions play a big role in how effectively the energy is managed. Changing battery temperatures require the controller to adjust its charge settings to maintain battery life and capacity. The controllers used on OOI moorings sense battery temperature and automatically adjust to assure best conditions to assure reliable operation.

“It’s really essential for us to maintain the proper charge levels for existing temperature conditions,” said Swartz. The OOI buoys encounter a wide range of temperatures: from subfreezing temperatures up to 40°C (over 100°F) when a buoy is sitting in the parking lot before it is deployed. When the buoys are deployed, water temperatures can vary widely from -1 to 33°C (~30 to 91°F), depending on seasonal conditions.

The new controller automatically regulates the amount of electricity going into the battery under such varying temperature conditions. If the  wind turbines are generating more energy than the battery needs, for example, the controllers direct excess power into an external load that dissipates heat and adds resistance to the spinning of the wind turbines, preventing the turbines from spinning too fast, possibly damaging their bearings.

“As parts of the OOI infrastructure need replacing or to be upgraded, this offers us the opportunity to find more efficient, and often times, off-the-shelf, less-expensive replacements that will help us keep the arrays functioning and data flowing,” Swartz said. “It’s a winning combination for all parts of the operation.”


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Marine Mammal Operations Aboard R/V Neil Armstrong During Pioneer 17

The Northeast Fisheries Science Center (NEFSC) had the opportunity to participate on leg two of the Pioneer Array research cruise aboard the R/V Neil Armstrong. The dates for the second leg this year were November 7 – 15 2021. This time frame was critical for us because our main asset for assessing right whale distribution, the NOAA (National Oceanic and Atmospheric Administration)Twin Otter aircraft was scheduled to depart for the Gulf of St. Lawrence Canada, and would not be available. Since 2010 the distribution of the North Atlantic Right whale has changed significantly, and it has become increasingly important to survey more broadly within the range to determine if there are aggregations of right whales in unprotected areas.

Participating scientists from the NEFSC for this cruise were Chris Tremblay and myself, Pete Duley. Chris was brought on for his expertise in acoustics, specifically with the deployment and monitoring of sonobuoys for the detection of North Atlantic Right whales and other large baleen whales. This additional element to our research plan was added to detect right whales in weather when visual observations were not ideal, and to access call types associated with different behaviors from observations with right whales in good visual conditions. Deployment of sonobuoys were conducted with very low or no impact to the mission of the work on the Pioneer array.  November 12 was the only day of the entire cruise in which we were unable to conduct visual observations due to the weather. The Northeast U.S Shelf Long Term Ecological Research (NES-LTER) group was conducting a CTD survey across the shelf break and we used this opportunity to make four sonobuoy drops in association with their survey. We are still analyzing the acoustic recordings form the cruise, but at this point feel that they were a valuable addition to the research.

Sonobuoys are launched by hand from the back deck, once permission has been granted by the bridge. The instruments are not meant to be retrieved and can record for up to eight hours. The instruments send information from their hydrophones by VHF transmission (line of sight) to an antenna mounted on one of the upper decks (01), and scuttle themselves after eight hours of recording.

[media-caption path="/wp-content/uploads/2021/11/Bigeyes.png" link="#"]Marine Mammal Observer Chris Tremblay uses Bigeye binoculars to search for right whales during mooring operations by the Pioneer 17 team. Credit: Peter Duley. [/media-caption]

Marine mammal visual operations aboard the Neil Armstrong were conducted from the 01 Deck. Our Bigeye stand would not fit the predrilled holes in the 01 deck and this required Kyle Covert, the ship’s welder,  to manufacture some iron fasteners to secure the stand and Bigeye binoculars. This issue was fixed during the staging prior to our departure and worked quite well. The marine mammal observation deck (deck 02) was unavailable to us this year because of Bigeye stand mounting issues. There are plates welded into the deck for the stands, but no predrilled bolt pattern in the deck. The marine mammal deck also has a desk with access to the ship’s SCS (Sea Control Ship) feed, and offers a better vantage point because it is higher. However, even while working in higher sea states we were unaffected by spray from the bow on the 01 deck, and this worked out quite well for this cruise. We brought with us a small desk, some deck chairs, and ratchet straps for securing everything.

The crane on the 01 deck is on the starboard side and caused a slight visual obstruction in panning from 090 to 270 degrees. The location of the Bigeyes aft on the port side, however, provided good visibility nearly to 180 degrees on the port side, which proved useful when stationary during the Pioneer Array mooring deployments and recoveries. We recorded whales aft of the ship during several of these stationary observation periods. Visual observations while underway were conducted from 07:30 to 16:45 and observers rotated from the Bigeyes to the recorder position on the half hour. At the locations where the ship was stationary working on mooring operations for extended periods of time, Chris and I did a scan of the area every 15 minutes. We are still working on analyses of the visual data, and although we did not observe any right whales during the Pioneer 17 cruise we feel that the ship is a great asset for our work and would love for the collaborative effort to continue. Thank you so much for the opportunity to participate this year!

Written by Peter Duley, Fisheries Wildlife Biologist, Northeast Fisheries Science Center

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