Three-Dimensionality of the Seafloor stevedeneef.photoshelter.com blog.thesietch.org...

Destructive Fishing Practices

Three-Dimensionality of the Seafloor

stevedeneef.photoshelter.com

blog.thesietch.org

flowergarden.noaa.gov

Destructive Fishing MethodsBottom trawlingDredgingDynamite fishingTraps

Bottom TrawlingOccurs from

subpolar to tropical latitudes

Occurs in public waters

Few scientific studies (but increasing)

Time of recovery to original structure – years to centuries www.duke.edu

www.saveourseas.com

Bottom TrawlingBottom Trawling InfoHow a Trawl WorksTrawling on a Non-vegetated BottomTrawling in Seagrass

Effects of scallop dredgingon a gravel bottom:George’s Bank: 84 m depth

Un-fished area

Fished area 500 m away

http://oceana.org/

Effects of TrawlingHomogenizes sediments; eliminates

microtopography; overturns, moves, and buries boulders and cobbles; leaves long-lasting grooves

Crushes and buries some infauna, exposes others

Removes, damages or displaces most structure-forming species

Eliminates most late-successional speciesReleases large pulses of carbon

Similarities with Clear-cuttingBoth activities:

Remove large amounts of biomass from the ecosystem

Alter the substratumEliminate late successional speciesRelease large pulses of carbon to the overlying

air or water

nefc1.org savethedeepsea.blogspot.com

Frequency of trawling in some representative areas

Trawling and Bycatch

www.njscuba.net

Bycatch by Gear Type

TEDs and BRDs

http://kurrawa.gbrmpa.gov.au/

Dredging

www.southlandnz.com

hatchery.hpl.umces.edu

Dredging• Oyster Dredging in WA State

Dynamite fishingJacques Cousteau videoDynamite fishing - humans and sharks react

Widespread in Southeast Asia, the Aegean Sea, and coastal Africa

Trap and Pot FishingUsed for lobsters, crabs, fishWide range in size of traps

www.montereyfish.comwww.coexploration.org

Habitat degradation in trap fisheries:• Damage to sessile benthic fauna/flora during

placement, fishing, and hauling