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Marine Debris Research: Ecological and Economic Assessment of Derelict Fishing Gear in the Chesapeake Bay

By: Amy Uhrin, Chief Scientist for the NOAA Marine Debris Program

The Chesapeake Bay blue crab fishery accounts for 50% of the United States blue crab harvest, and is worth about $80 million annually. It’s estimated that about 600,000 crab traps (also called “pots”) are actively fished on an annual basis in the Bay. Some crab pots become lost (derelict) when the pot’s buoy line becomes detached or cut, either by vessel propellers, faulty lines, or vandalism. Strong storms can also move pots from their original deployment location, making them difficult to relocate. In addition, pots may be abandoned, as has been observed at high rates in some regions of the Bay. Once lost, derelict pots can damage sensitive habitats and continue to capture blue crabs and other animals, often resulting in their death. To assess the ecological and economic impacts of derelict blue crab pots in the Chesapeake Bay, a diverse team of researchers from CSS-Dynamac, Inc.; Versar, Inc.; the Virginia Institute of Marine Science; and Global Science & Technology, Inc. recently completed a comprehensive Bay-wide assessment, funded by the NOAA Marine Debris Program.

A derelict drab trap.

Blue crabs are harvested using rigid, cube-shaped wire traps that are galvanized or vinyl-coated. Here, diamondback terrapins can be seen inside a standard pot. (Photo Credit: CCRM/VIMS)

This study estimates that some 145,000 derelict crab pots exist in the Chesapeake Bay, with 12-20% of actively-fished pots becoming lost each year. Not surprisingly, many derelict pots are found in areas of the Bay with heavy recreational and commercial boat traffic or fishing activity. These derelict pots kill over 3.3 million blue crabs annually. In addition, many other economically-important species can be impacted, such as white perch (3.5 million captured annually) and Atlantic croaker (3.6 million captured annually). Derelict pots thus “compete” with pots that are in active use —they catch or attract crabs that could otherwise be caught by active pots, and can therefore reduce commercial harvests.

Map of Chesapeake Bay with colors indicating density of derelict pots.

The predicted spatial distribution of derelict crab pot densities in Chesapeake Bay. (Photo Credit: CSS-Dynamac, Inc.; Versar, Inc.; Virginia Institute of Marine Science; and Global Science & Technology, Inc.)

Through statistical modeling, this study found that targeted derelict crab pot removal programs greatly increase the number of crabs caught by actively-fished pots, resulting in significant economic benefits for the fishery. The model estimated that derelict pot removals increased Bay-wide crab harvests by over 38 million pounds over a six-year period (2008 to 2014), amounting to $33.5 million in added revenue (in 2014 dollars). This study also found that pot removals are most effective when they focus on areas with intensive crab fishing activity.

This study also suggests management actions that may help in reducing the number of new derelict pots and their associated negative impacts. These include minimizing boat traffic in popular crabbing areas and educating boat operators about avoiding active crab pots, which would help reduce the number of cut buoy lines. Creating and maintaining derelict pot recovery programs, or incentivizing watermen to remove lost pots, would also help reduce the number of derelict pots in the Bay. In addition, outfitting crab pots with biodegradable “escape hatch” panels would reduce mortality of captured animals.

In addition to the Chesapeake Bay assessment, the team also created a Guiding Framework for derelict fishing gear assessments, which can be applied to other fisheries and/or regions interested in conducting similar studies. The final report for the Chesapeake Bay Assessment and the Guiding Framework document can be found on our website.


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Marine Debris Research: What Happens When Salmon Eat Foamed Plastic?

By: Carlie Herring, Research Analyst for the NOAA Marine Debris Program

After the 2011 tsunami in Japan, the Alaskan coastline experienced a rise in debris washing ashore. Although there was an increase in many types of debris, the abundance of expanded polystyrene (think foamed plastic) increased on some beaches by as much as 1,600% from 2008 to 2012. This spurred interest by NOAA scientists at the Auke Bay Laboratory in Juneau, Alaska, to explore the interaction between this foam debris and an important Alaskan fishery species: pink salmon (Oncorhynchus gorbuscha). The researchers were interested in both determining the potential of juvenile pink salmon to ingest small foam pieces and understanding the physiological consequences of ingesting foam debris (such as, would ingesting foam alter their growth rates?). Through support from the NOAA Marine Debris Program, the team began an experimental study to address these questions.

Foam debris on a beach.

Polystyrene and other plastics on a remote beach in Alaska in 2012. (Photo Credit: NOAA)

To measure the amount of polystyrene foam ingested and to test the impact of ingestion on growth, researchers mixed polystyrene foam pieces with food and fed the mixture to juvenile pink salmon for five weeks. The researchers developed a methodology to accurately measure the amount of polystyrene foam in the gut contents of the fish. Weekly measurements of the length and weight of fish were taken and after five weeks, this new methodology was used to record their stomach contents. In addition, nucleic acid (RNA/DNA) ratios within the fish were evaluated to examine fish growth rate at a cellular level.

Although the nucleic acid ratios showed differences between foam-fed fish and those that did not ingest foam, there was no difference in growth (fish weight and length) between the two groups. The researchers postulated that the difference could be from the body’s response to the introduction of toxic chemicals from the ingested foam. Overall, the experiment showed that polystyrene can be consumed by juvenile pink salmon when it is present in the ecosystem.

The scientists noted that this was a short-term study and suggested longer exposure studies in the future to more definitively test the effects of polystyrene ingestion on the growth of juvenile salmon. They also suggested that varied feeding levels may better reflect fish behaviors and feeding patterns in the natural environment.

For more on research projects supported by the NOAA Marine Debris Program, visit our website.


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Now Open: FY17 Marine Debris Research Grant Opportunity

The NOAA Marine Debris Program is proud to announce our “Marine Debris Research” federal funding opportunity. This opportunity provides funding to support eligible organizations to conduct research directly related to marine debris through field, laboratory, and modeling experiments. Applicants requesting funding for research that explores the ecological risk associated with marine debris, determines debris exposure levels, and examines the fate and transport of marine debris in nearshore, coastal environments are welcome to apply. Projects may address one or more of these research priorities and should be original, hypothesis-driven projects that have not previously been addressed to scientific standards. To apply for this grant opportunity, visit Grants.gov.

For more information about the program’s competitive federal funding opportunities, visit our website.


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Lobster Trap Debris in the Florida Keys: A Look Back

The NOAA Marine Debris Program 10 year anniversary identity marker.

 

Over the years of the NOAA Marine Debris Program, there have been many efforts around the country to rid our waters and shores of marine debris. As part of our ten-year anniversary celebration, let’s take a look back at one of those efforts in our Southeast region.

 

Derelict fishing gear can cause lots of problems, including damaging important and sensitive habitats, ghost fishing, and posing hazards to navigation. Unfortunately, derelict commercial lobster and crab traps are a prominent type of marine debris in the Florida Keys.

Back in 2007, the NOAA National Centers for Coastal Ocean Science’s (NCCOS) Center for Coastal Fisheries and Habitat Research (CCFHR), funded by the NOAA Marine Debris Program, partnered with the Florida Fish and Wildlife Conservation Commission to research this issue. Using towed-diver surveys, they identified and counted trap debris as well as any other marine debris they encountered in the Florida Keys National Marine Sanctuary.

A researcher surveys derelict traps during a towed diver survey.

A researcher surveys derelict traps during a towed diver survey. (Photo Credit: NOAA)

From these surveys, they found 1,408 marine debris items, almost 70 percent of which were trap-related debris! This included both ghost traps (which continue to actively fish, trapping and killing marine animals) and non-fishing traps in various stages of degradation. From their data, they estimated that over 85,000 ghost traps and over a million non-fishing traps could be found in the waters of the Florida Keys at that time. They also determined that winds likely play a role in moving derelict traps, since the surveyed trap debris was found in highest densities in coral reef habitats (a place not commonly targeted by fishermen).

Research like this is an important part in the fight against marine debris. This project helps us to understand where trap debris accumulates and thus allows us to more effectively focus removal efforts. For more information on this project, check out this old blog post, the scientific paper published from the study, and the Marine Debris Clearinghouse. For more on research projects supported by the NOAA Marine Debris Program, check out our website.


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A New Study Looks at Derelict Traps in the Florida Keys

Research is an important part of our fight against marine debris, as it allows us to learn more about the topic and be better able to target and address it in the future. Thanks to a new study by our very own Chief Scientist, Amy Uhrin, we now know a little more about derelict lobster traps and how they impact habitat in the Florida Keys. Read all about it and get the link to the scientific paper in this NOAA Response and Restoration blog post.

A derelict lobster trap frame with bio-fouling (most of the side slats are missing) sits on mixed seagrass and hard-bottom habitat.

Check out the blog post on NOAA’s Response and Restoration blog for a detailed look at this exciting study. Here, a derelict lobster trap frame with bio-fouling (most of the side slats are missing) sits on mixed seagrass and hard-bottom habitat. (NOAA)


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What’s Up With Derelict Crab Pots?

Derelict crab pots have recently been popping up in the media, and you may be wondering, “what’s up with all these crab pots?” Well, derelict pots are numerous in heavily fished waters and can create all sorts of problems for both the habitat where they are found and the local economy. Recently, there have been many efforts that are taking advantage of closed crabbing seasons to remove some of these derelict pots and learn more about them.

Derelict crab pots are a big problem for many coastal areas. These traps that have been lost, abandoned, or discarded into the marine environment end up there in a variety of ways. Oftentimes, crab pots are lost after bad weather, being improperly set up, or from lines being inadvertently cut from passing vessels. Once a crab pot becomes derelict, it can start to wreak some havoc. Not only can derelict pots become navigational hazards or damage sensitive coastal habitats, but they can also result in a phenomenon called “ghost fishing.” Ghost fishing occurs when derelict fishing gear continues to capture marine life, a catch that ends up going to waste and often results in the mortality of whatever organism was captured. This often also translates to economic loss, a connection that was recently explored in a newly published study by the Virginia Institute of Marine Science (VIMS).

A boat full of derelict crab pots. (Photo Credit: Center for Coastal Resources Management (CCRM)/VIMS)

Derelict crab pots can be damaging in many ways. (Photo Credit: Center for Coastal Resources Management (CCRM)/VIMS)

This VIMS study details how fishermen can suffer economic losses associated with derelict crab pots. As derelict pots remain in local waters, they continue to capture marine organisms, including harvestable crabs. These crabs go to waste and, having already been captured by a derelict pot, can no longer be caught by professional crabbers who rely on such catches for their livelihood. By removing derelict pots, these financial losses can be avoided. For more information on this study, check out this blog post.

Derelict crab pots are removed from coastal waters in New Jersey. (Photo Credit: Elizabeth Zimmermann, Stockton University)

Derelict crab pots are removed from coastal waters in New Jersey. (Photo Credit: Elizabeth Zimmermann, Stockton University)

To avoid these financial losses and other negative impacts associated with derelict crab pots, there are many efforts underway to remove them. Three new projects in New Jersey aim to both remove derelict pots and educate the public about how to avoid losing pots in the first place. Check out this blog post to learn more about these projects. In Louisiana, derelict crab pots are such a big issue in the New Orleans area that the Louisiana Department of Wildlife and Fisheries is hosting two “Derelict Crab Trap Rodeos.” These are day long events during which volunteers work to remove derelict crab traps from local waters. The first event is this coming Saturday, February 13th, so if you’re in the area, stop by and help remove some derelict pots! But don’t worry if you can’t make this one, you’ll get a second chance at the next event on February 20th. For more information on this project, check out our website.


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The Dilemma of Derelict Gear

A boat full of derelict crab pots. (Photo Credit: Center for Coastal Resources Management (CCRM)/VIMS)

Derelict crab pots can be damaging in many ways. (Photo Credit: Center for Coastal Resources Management (CCRM)/VIMS)

Derelict fishing gear can create a lot of problems: hazards to navigation, damage to sensitive habitats, and ghostfishing. Ghostfishing occurs when lost or discarded fishing gear that is no longer under a fisherman’s control continues to capture marine life. This is obviously bad news for local marine animals that can end up ensnared in derelict gear, but it can be harmful to local fisheries too. That’s what scientists at the Virginia Institute of Marine Science (VIMS) think and set out to prove.

VIMS researchers considered that apart from the obvious financial loss of losing gear, fisheries may suffer due to competition between active and derelict gear, specifically blue crab pots. Their research and analysis, funded in part by the NOAA Marine Debris Program, evaluates the hypothesis that derelict crab pots compete with active gear by attracting target species that might otherwise be attracted to actively-fished crab pots. This reduces commercial fishery harvests and revenues and is thus a lose-lose situation for both the crabs and crabbers.

A side-scan sonar image of an active crab pot (on the left, with attached buoy) and a derelict crab pot (on the right, missing an attached buoy) in the Chesapeake Bay. (Photo Credit: CCRM/VIMS)

A side-scan sonar image of an active crab pot (on the left, with attached buoy) and a derelict crab pot (on the right, missing an attached buoy) in the Chesapeake Bay. (Photo Credit: CCRM/VIMS)

To test this hypothesis, VIMS researchers created a model that allowed them to assess fishery harvests in Virginia with and without derelict gear present. Using this model, they compared fishery harvests with derelict crab pots removed via a large-scale removal project, and a hypothetical scenario where no pots were removed. The comparison also accounted for other factors that could potentially impact harvests, such as stock abundance and environmental conditions, so that the effect of derelict gear removal could be isolated.

The results of this comparison indicated that the Virginia Marine Debris Location and Removal Program, which removed 34,408 derelict crab pots over six years, increased crab harvests in Virginia by 27%, or by 30 million pounds valued at $21.3 million for fishermen! This was the direct result of reduced gear competition and thus the improved efficiency of active crab pots. Removal was found especially effective in highly-fished areas with higher rates of pot loss. Extending their findings globally, VIMS researchers speculate that removing about 10% of derelict pots and traps could increase crustacean harvests by over 600 million pounds per year. These findings exhibit just one of the many damaging effects of derelict fishing gear.

A figure demonstrating the Virginia crab harvest with derelict crab pots removed (blue line) and without the pots removed (red line). (Photo Credit: VIMS)

A figure demonstrating the Virginia crab harvest with derelict crab pots removed (blue line) and without the pots removed (red line). (Photo Credit: VIMS)

This study and its results were accepted for publication by the journal Nature Scientific Reports (for you non-science folks, that’s a big deal), with VIMS researchers A. M. Scheld, D. M. Bilkovic, and K. J. Havens as authors on the paper. For more on these and associated efforts, check out the NOAA Marine Debris Program website.