Study results: 1,570 potential derelict traps off the NH Seacoast

1,570 Potential Derelict Lobster Traps located during 4 days of Derelict Fishing Gear Sidescan Sonar Survey: Portsmouth, NH and the Isle of Shoals

Rozalia Project for a Clean Ocean conducted a 4 day sidescan sonar survey to locate derelict fishing gear around the coastal waters of Portsmouth, NH and the Isle of Shoals on the behalf of the Blue Ocean Society for Marine Conservation, NH Sea Grant and UNH Cooperative. The Sonar survey was conducted as part of the Marine Debris to Energy Project, a NOAA funded project to detect and remove marine debris along the coastline from southern Maine to northern Massachusetts. The Sonar survey was also supported by Optima Bank, Portsmouth, NH and the Kittery Point Yacht Yard, Kittery, ME.

METHOD:

The survey was conducted from Rozalia Project's 60ft sailing research vessel American Promise utilizing a Tritech Starfish sidescan sonar towed from the starboard quarter of the vessel at speeds ranging from 1.9-4.3 knots, in depths of water from 20-135 feet.

The aim of the survey was to locate derelict fishing gear and investigate it's volume and geographical distribution, in this case predominantly derelict lobster traps (pots)

Potential derelict lobster traps were identified on the sonar image by the following criteria: red dots=potential derelict trap, blue dots=active trap. The following examples are from the sonar survey:

1:    Groups of 3 or more lobster traps clumped together in close proximity:

2: Trap line of 3 or more with v shape or large deformation of the multi-trap line:

3: Individual traps with no active gear nearby:

4: Trap lines with no active lobster buoys within the Starfish’s range:

When potential derelict lobster traps where viewed on the sonar display, a snapshot was taken from the sonar image. In addition, waypoint locations and track information were recorded on an iPad utilizing Navionics charting software with snapshot time, waypoint number, track number, track start and finish GPS positions and track start and finish times recorded on data sheets.

RESULTS

1: Portsmouth Harbor/Piscataqua River Entrance (Fort Constituition to Gunboat Shoal): 

• 30.18 potential derelict traps per mile
• 9 tracks totaling 11.1nm were surveyed with 335 potential derelict lobster traps located

2: Gunboat Shoal to Rye Ledge:

• 102.86 potential derelict traps per mile
• 9 tracks totaling 10.14nm were surveyed with 1043 potential derelict lobster traps located

3: Isle of Shoals:

• 25.95 potential derelict traps per mile
• 7 tracks totaling 7.4nm were surveyed with 192 potential derelict lobster traps located

Survey totals:

• 1,570 potential derelict lobster traps located
• 28.64 miles of ocean were surveyed
• 296 waypoint locations of potential derelict traps recorded on sonar

CONCLUSION

1. Clumps/groups of lobster traps are often located at substantial terrain changes, for example, from sand to rock ledge (see below – ledge off Rye Harbor):

2. A higher volume of potential derelict lobster traps exists within 1.0 mile of the coast.  Density of inshore tracks  = 72.8 pdlt/mile
3. A higher volume of potential derelict lobster traps exists in proximity of highest density of active fishing gear (recommend ROV survey to confirm accuracy of sonar survey in these high density active trap areas).
4. A lower volume of potential derelict lobster traps exists offshore beyond 1.0 mile of the coast. Density of offshore tracks = 37.7 pdlt/mile.
5. A lower volume of potential derelict lobster traps exists in areas of lowest density of active gear (Isle of Shoals, and offshore tracks).
6. Derelict lobster traps are not static, during the survey, American Promise re-surveyed a shipwreck that was part of a 2008 Sonar Survey (below). During the 2008 survey the top of the wreck was covered by over 20 derelict traps. During our 2011 survey, the sonar image shows a wreck with no derelict lobster traps on it, just an active trap line to its port side. More research is needed on what moves the traps around (storms, draggers?) and where they go.

In the opinion of the Rozalia Project, the waters of coastal New Hampshire and the Isle of Shoals have a significant amount of derelict fishing gear on the sea floor with several inshore (within 1 mile of coast) locations where it has accumulated that would make removal of the derelict fishing gear feasible.

Technology Starfish style and a beautiful place

After a week in the mountains (awesome) of not necessarily rest but a different kind of work (OK, yes a little rest) we are back in action on American Promise. The Blue Ocean Society (who are dedicated to marine conservation and do a huge amount of work in everything from marine mammal conservation to beach clean ups to awareness campaigns - getting people to clean up after their dogs...) brought us in to do some survey work as part of a NOAA Marine Debris to Energy Grant. The goal this week is to look for and identify derelict fishing gear off the NH coast.

This is exciting because it marks the shift in focus for us from the trash pickup/education part of the summer to trash pick up/research part. We are getting to get a little farther from the docks and putting the equipment through some different challenges. Yesterday was

all about the Starfish side scan sonar. Tritech is the company who makes the Starfish and who generously donated this unit for the season. This is a small, towed sonar that looks down and to the side. It 'sees' objects by giving us both bright returns and showing shadows (see photo right). The equipment is incredibly easy to set up and get running and the challenge is to learn to read the images. We are getting better and look forward to today when we do more with the Starfish and hopefully put the VideoRay down for some confirmation video.

This week is also cool because we have interns from the Blue Ocean Society aboard helping us. Yesterday's crew: Abby, Mike and Ben were great each contributing their expertise and experience from getting the GPS that goes with the Starfish to work to giving us lots of excellent info on the local marine mammals (they are in the photo at the bottom getting ready to set off for the day). We're looking forward to having them back and meeting more for the next few days.

As high tech as the Starfish and ROV, we found the iPad to be an amazing tool for our work yesterday. We used the Navionics chart plotting app to show our transects and then put in waypoints of areas of interest. Then, we were able to bring that info over to Google Earth and get some quick visual info. Even our interns (classically trained in handheld GPS units and GIS software) were impressed!

Lastly, but by no means least, I have to say how beautiful a spot we are in. James found the Kittery Point Yacht Yard by looking for a place to moor for the week that was protected and on the seaward side of the bridge that leads to Portsmouth proper (where the headquarters of Blue Ocean Society is located). It is beautiful and even better, the guys who run this yard are friendly, helpful, know their stuff boat-wise and are interested in what we are doing. They are psyched to be the hosts of the Trash Bash tomorrow and have allowed us to be on the dock rather than the mooring (yipppee).

Speaking of support, this week is also made possible with the help of Optima Bank. They helped us get American Promise in the first place and are enthusiastically supporting what we are doing with her. We even get Carol from Optima onboard to help with the survey work tomorrow.

So, as I head off for day 2 of the survey, I want to say thank you to Tritech, Blue Ocean Society, KPYY and Optima Bank and to invite you all to the Trash Bash tomorrow (Thursday August 4) from 5-7 at the Kittery Point Yacht Yard. Thanks to Boat US Foundation, we will have drinks, food and goodies to give away and the event is free and open to the public.

Watch the coming storms.

rzm

ps. I could have done an entire post on this... but on the way here from Boston we say 7 Minke whales, a seal and a jumping tuna! See the Rozalia Project facebook page for photos from that day.