Bottom longline impact

Bottom longline impact

I am searching for any material describing or evaluating the bottom impact of bottom longlining or any other environmental impact generated from bottom longlining. I have seen that longlines tend to generate more ALDFG than other gears.

  1. Does anyone have results showing the same or different?
  2. How about references about directly impacting some specific bottom fauna, like long-living coral?
  3. We know set longlines (on the bottom) have a lesser impact than most other fishing gears. Can we quantify? Do we have research studies?

I would appreciate it if anyone could provide relevant references or grey literature.

Haraldur Arnar Einarsson

9 replies
  1. Antonello Sala
    Antonello Sala says:

    Your question stirred a memory. The 1998 publication, Effects of Fishing Gear on the Sea Floor of New England, includes a chapter by a bottom longline fisherman, Mark Leach that briefly describes some habitat impact from bottom longlines. Hope this helps, Mike Pol

  2. Antonello Sala
    Antonello Sala says:

    Here are a few comments/studies that I searched up relative to work off of Alaska. Their use and, apparently, further planned use of a camera system designed and used in Australia led me to look up what I could find on that development too. See below:

    “Disturbance attributable to longline gear was widespread (76% of the transects) but very localized, occurring on only 5% of the seafloor. Derelict longline gear was seen on five transects.”
    Coral habitat in the Aleutian Islands of Alaska: depth distribution, fine-scale species associations, and fisheries interactions

    R. P. Stone Coral Reefs volume 25, pages 229–238 (2006)
    3.7. Longline Impacts study Background and Objectives: Disturbance from longline fishing to sensitive coral and sponge habitats has been documented in Alaska but the extent of and mechanisms of disturbance have not been well studied compared to bottom trawling. Observations in red tree coral thickets in the eastern Gulf of Alaska indicate that 17% and 20% of the “standing stock” of corals and sponges, respectively, have been damaged by longlines (Stone et al. 2014). Corals and sponges are common bycatch in both commercial fisheries and stock assessment surveys using longlines clearly indicating interactions between the gear and sensitive habitats. Bycatch of branching corals is generally higher than that of sponges, presumably due to differences in how easily they can become entangled in the gear. The goal of this project was to examine the behavior of longline gear in situ during all stages of fishing. Approach: This pilot project used two tools to examine longline disturbance of benthic habitat. The first tool was a camera system was developed that took intermittent pictures of the seafloor during all stages of the set (deployment, on-bottom fishing and retrieval). The second tool was a series of accelerometers that were attached to the longline ground gear. Both tools were deployed on a longline survey vessel that was conducting stock assessment surveys in 2013 and 2014. The camera system was deployed in both years, while the accelerometers were deployed in 2014 only. 40 Significant results to date: Analyses of the images collected in 2013 did not indicate that the groundline of the longline moved along the seafloor during deployment. There were only two successful tests of the camera system that year, and in both cases the camera was stationary throughout the 6 hour set. Both deployments were conducted in sandy benthic habitat. In 2014, 12 camera deployments were conducted. Image analyses for these deployments are still underway. The accelerometers were deployed on 12 longline sets in six locations along the longline in 2014. The accelerometer data are very noisy (Figure 29), and some Kalman filtering is necessary to analyze the data. For most cases, the data indicates minimal if any movement of the longline during setting, fishing and recovery. However, there were a few cases where there was some indication of increased acceleration during the set that could have indicated the longline was traveling across the seafloor. These results are very preliminary and analyses are still ongoing with this data. Funding: Vessel time and personnel time were contributed in kind by the AFSC and the annual longline survey. The DSCRTP contributed ($18,125) for the purchase of underwater equipment and travel to and from the field locations in FY13 and FY14. Point of contact: Chris Rooper, AFSC-RACE Division,

    Deep-Sea Coral Research and Technology Program : Alaska Deep-Sea Coral and Sponge Initiative final report
    2017 By Rooper, Christopher N.
    NOAA technical memorandum NMFS-OHC ; 2
    (Chris Rooper has since moved to the Canadian DFO:

    Autonomous video camera system for monitoring impacts to benthic habitats from demersal fishing gear, including longlines
    Author links open overlay panel
    Robert Kilpatrick, Graeme Ewing, Tim Lamb, Dirk Welsford, Andrew Constable
    Deep Sea Research Part I: Oceanographic Research Papers, vol. 58, issue 4, pp. 486-491
    Pub Date: April 2011

    Development of a deep-water camera system capable of deployment on fishing gear

    Welsford, D.C., G.P. Ewing, A.J. Constable, T. Hibberd and R. Kilpatrick. 2014. Demersal fishing interactions with marine benthos in the Australian EEZ of the Southern Ocean: An assessment of the vulnerability of benthic habitats to impact by demersal gears. Final Report FRDC project 2006/042. Australian Antarctic Division: 258 pp. Availability?

    Rose Craig

  3. Antonello Sala
    Antonello Sala says:

    You might check with the South Atlantic (based on Charleston SC USA) and Gulf of Mexico (Tampa, Florida USA) Fishery Management Councils. These are the regional fishery management councils for the federal waters fishery management in the southeast part of the United States. I believe both councils have regulations prohibiting bottom longlines in some of the coral and what they call “live bottom” areas they manage. Council staff can probably give you information and references for the studies they used to develop these regulations.
    John Gauvin

  4. Antonello Sala
    Antonello Sala says:

    This study is a decade old but it compares the bycatch and habitat impacts of the various gear (trawls, pots, longlines) used in the U.S. West Coast Groundfish fishery.

    Jenkins, L.D. and Garrison K. 2013. Fishing Gear Substitution to Reduce Bycatch and Habitat Impacts: An Example of Social-Ecological Research to Inform Policy. Marine Policy. 38: 293-303.

    Kiki Jenkins

  5. Isara Chanrachkij
    Isara Chanrachkij says:

    have not any information about the impact of bottom longline to the habitat in term of ALDFG.
    As SEAFDEC is a Training Center, we trained our trainee to apply Bottom Vertical Longline in the coral area, rocky area and continental slope. The mainline is lifted up above the sea bottom to reduce entangling with the rocky and corals. Please find the construction and design of BVL in our website.
    Thank you

  6. Craig Rose
    Craig Rose says:

    Another potentitally relevant paper – This is with pots, but includes pots fished on longlines, perhaps with some similarities for seafloor impact issues.

    The ups and downs of traps: environmental impacts, entanglement, mitigation, and the future of trap fishing for crustaceans and fish Bradley G Stevens
    ICES Journal of Marine Science, Volume 78, Issue 2, March 2021, Pages 584–596,


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