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Biology

The Ghastly Impacts of Ghost Fishing Gear

Arthur, C., Sutton-Grier, A. E., Murphy, P., & Bamford, H. (2014). Out of sight but not out of mind: Harmful effects of derelict traps in selected U.S. coastal waters. Marine Pollution Bulletin. doi:10.1016/j.marpolbul.2014.06.050

 Doi:10.1016/j.marpolbul.2014.06.050

One aspect of the fishing industry we might not think about is lost fishing gear.  Ranging from a hooked  fish, that snapped your line and got away to lost nets and traps, the fact is that much of this lost gear will still actively ‘fish’ when it’s sitting on the ocean bottom.  The catch is that the ‘catch’ will not be hauled in to the market and instead will possibly remain captured in the traps for months and potentially die without ever escaping.  This phenomenon has coined the term “ghost fishing,” and it may be more common than one might think.

One example of how ghost fishing gear might come about is the setting of lobster pots, crab traps, or the like in the middle of a heavily trafficked harbor or channel where boats are more likely to accidentally snag a line in their propeller and cut the line.  There are also, unfortunately, intentional loses of traps as well.  In some cases, it is considered ‘cheaper’ by fishermen to discard old and unusable traps overboard instead of paying exorbitant fees to dispose of them on land.  In other cases, vandalism acts can occur and lines may intentionally be cut by fishing competitors.  The authors of this study realized the lack of published data that exists on derelict fishing traps and the negative impacts they may have on certain recreational and commercial fisheries and synthesized various datasets from seven studies throughout the coastal United States in a qualitative manner.

The Fisheries in Question                                                                      

The fisheries investigated in this study include the Dungeness crab fisheries in Alaska and Puget Sound, the blue crab fisheries in Maryland, Virginia, and North Carolina, the spiny lobster fishery in Florida, and the coral reef fishery in the U.S. Virgin Islands.

arthur et al - DFTs study sites

What they found

The highest density of derelict fishing traps was located in the Chesapeake Bay region, where the amount of derelict traps ranged from 28 to 75 per km2.  It was estimated that at any one time, around 40% of these traps can be ‘ghost fishing,’ which extrapolates to around 20 dead crabs per trap per year, or 376 dead individuals per km2 per year.  Conversely, the lowest density of derelict traps was located in the US Virgin Islands, averaging only 5 traps per km2.  The number of individuals likely to die in the traps (as many as 178,874 Dungeness crab in Puget Sound and 913,000 blue crabs in Virginia) and the amount of time the traps are likely to ‘ghost fish’ for (aprx. 0.3 – 6+ years) can largely depend on the design of the trap.

arthur et al - DFTs trap pics

The money in the pot

Estimates of economic impacts were difficult to ascertain due to variability between studies and highlights the need for collaborations with social scientists.  Summarized compilations of previously reported economic impacts show 4.5% of the Dungeness crab harvest may be lost every year due to derelict fishing traps in Puget Sound.  This may not sound like a lot, but that’s a loss of $744,000!  Additional estimates show that the Virginia portion alone of the Chesapeake Bay may be losing 1% of the blue crab harvest, totaling around $304,000.  Another factor to consider is the cost of the lost traps to the fishermen themselves, which can add up to a sizeable portion of money (upwards of $100,000/year for some firsheries).

Other Impacts

Derelict traps may additionally affect the breeding status of populations (i.e. by catching egg-bearing females), and may be capturing non-target species (i.e. species the traps are not intended for), such as the diamondback terrapin, a species of concern in the Chesapeake Bay region.  While the authors point out the potential positive impacts the traps may have in terms of providing habitat (i.e. structure for oyster growth), there are likely to be more negative impacts, such as destruction of eelgrass and saltmarsh habitat due to the presence of abandoned traps.

arthur et al - traps as habitat

It is clear that more research is needed to flush out the deleterious effects of derelict fishing traps and most ecosystems will likely benefit from improved management strategies of ghost fishing gear.  Below are the suggestions put forward by the authors as future steps to take in terms of reducing the loss of fishing gear in the first place and minimizing impacts of the existing abandoned traps.

Table 1 – Summary of recommendations and research needs put forward by Arthur et al. in this study (2014).

Summary of recommendations

  • Examine the regional context and challenges resulting in the loss of DFTs to drive effective policy solutions.
  • Increase spatial planning to reduce accidental DFT loss due to boating incidents.
  • Provide low-cost, easy disposal options as incentive to reduce improper disposal. Educate fishing communities about the impacts of DFTs to reduce accidental loss and intentional loss through vandalism.
  • Remove DFTs when possible, especially in areas that demonstrate high loss rates. Standardize techniques for removal, including determination of which traps may be more beneficial as habitat.
  • Reduce impacts of DFTs by making sure escape panels are present and functioning as intended.
  • Reduce impacts of DFTs through necessary research with the fishing industry to develop best options for trap construction that reduce ghost fishing without reducing catch.
  • When available, consider using supplemental funds for DFT removal.
Summary of research needs

  • Studies tying the impacts of DFTs to stock assessments, to understand the impacts on fishery populations.
  • Studies designed (a priori) to measure the economic cost of DFTs on commercial fisheries. Collaborative research with the fishing industry to design traps that allow species to readily escape when traps become derelict.
  • Studies estimating the population-level impacts of DFTs on species of concern.
  • Research on the movement and behavior of DFTs in varying physical environments, to capture the dynamic rate of DFT import and export from a system.
  • Studies to develop a more comprehensive understanding of the causes of gear loss, including improper disposal of traps on land, and understanding motivations for intentional trap loss.
  • In areas with more severe impacts from DFTs, research into alternative harvesting methods that have fewer impacts.
  • Science that focuses on debris aggregations near sensitive habitats and organisms, where substantial damage from DFTs may occur.
  • Complimentary social science research to discover which policies and regulatory mechanisms would be most effective.
  • Efforts to standardize metrics, to inform spatial comparisons and meta-analyses in the future

 

For more info on ghost fishing gear:

http://oceanservice.noaa.gov/facts/ghostfishing.html

http://www.ghostfishing.org/

http://www.fao.org/fishery/topic/14798/en

 

Discussion

2 Responses to “The Ghastly Impacts of Ghost Fishing Gear”

  1. Thank you for exposing the waste of ghost traps. I would have to add that ghost NETS are far more damaging to sea life.

    Discarded or lost fishing nets trap fish, cetaceans and highly migratory and endangered species like sharks, turtles, swordfish, billfish and tuna. In addition, the nets are not stationary but float through vast amounts of water, cover large distances and kill indiscriminately.

    Posted by Mary M Hamilton-SandyHook SeaLife Foundation | August 29, 2014, 10:20 am
    • Hi Mary,

      That’s a great point you’ve brought up and while this study was focused on trap fisheries, ghost nets and other fishing gear are definitely a critical component of the ghost fishing picture. Hopefully more research can be done in this area in the future. Thanks for your comment!

      Posted by Erin Markham | August 29, 2014, 2:16 pm

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