Bottom Trawling: A Destructive Fishing Practice That Devastates Seafloor Habitats

Yes. Bottom trawling is the most destructive fishing method in widespread use. Weighted nets (doors, rollers, rockhopper gear) dragged across the seafloor catch target species but destroy the habitat that produces them.

Mechanics of Destruction

• Physical plowing: Doors (1-5 tons each) cut furrows 10-30 cm deep. Repeated passes = agricultural tillage of seabed.
• Biogenic habitat removal: Cold-water corals (Lophelia, 4,000+ yr old), sponge gardens, seapen fields, bryozoan thickets — centuries to millennia to form, minutes to destroy.
• Bycatch: 20-90% of catch non-target (juveniles, non-commercial, endangered). Turtles, sharks, rays, mammals, seabirds.
• Resuspension: Sediment plumes smother filter-feeders, release buried contaminants, reduce light.

Scale

4.9M km² trawled annually (half world's continental shelf). Some areas trawled >10x/yr. Deep-sea trawling (>200 m) expanded 1980s-2000s as coastal stocks collapsed.

Ecological Consequences

• Community homogenization: Opportunistic scavengers (hermit crabs, starfish) replace diverse specialists.
• Trophic cascades: Habitat loss → prey loss → predator collapse.
• Carbon release: Seabed carbon (millennia-sequestered) resuspended → CO₂. Trawling emits ~1.5 Gt CO₂/yr (equiv. aviation).
• Recovery time: 5-10 years (sand/mud), 50-100+ years (gravel), centuries (coral), never (seamounts).

Regulation

• EU: Ban >800 m (2016), >400 m in vulnerable areas.
• RFMOs: SPRFMO, NAFO, SEAFO — closures on seamounts/VMEs (Vulnerable Marine Ecosystems).
• National: US (EFH closures), Canada, NZ, Australia — progressive restrictions.
• Voluntary: MSC certification excludes bottom trawl on VMEs.

Alternatives

Longline, trap/pot, hook-and-line, midwater trawl (pelagic), jigging. Lower impact, higher cost, more labor. Transition requires policy: buyout programs, gear conversion subsidies, spatial zoning (trawl lanes vs. closures).

The seafloor is not a farm field. It's a forest we're clear-cutting blind.