Non-target benthic invertebrates are caught as bycatch in huge volumes, but precise numbers are not available.
| Location | Gear | Technique | Species | Results | Catch | Effect on Target Catch | Type | Reference | |
|---|---|---|---|---|---|---|---|---|---|
| North Coast, Australia | Trawls | Excluder devices | Invertebrates | Reduced bycatch if small individuals by 37.6% | Prawns: White Banana (Fenneropenaeus merguiensis), Red-legged Banana (F. indicus), Brown Tiger (Penaeus esculentus), Grooved Tiger (P. semisulcatus), Blue Endeavour (Metapenaeus endeavouri), and Red Endeavour (M. ensis) | Increased by .05% | Field study in the wild | Kon's Covered Fisheyes BRD Trial Report | |
| Southeastern Australia | Traps | Trap-net modification | Bony Fishes, Invertebrates | 87% reduction in yellowfin bream, 84% reduction in undersized crab | Blue swimmer crab (P. armatus) | No effect | Field study in the wild | Cumulative selectivity benefits of increasing mesh size and using escape gaps in Australian Portunus armatus traps | |
| Southeastern Australia | Traps | Trap-net modification | Invertebrates | 51-100% reduction of juvenile crab | Blue swimmer crab (P. pelagicus) | No effect | Field study in the wild | Performance of industry-developed escape gaps in Australian Portunus pelagicus traps | |
| Southeastern Australia | Traps | Trap-net modification | Bony Fishes, Invertebrates | 91-mm traps retained significantly fewer (by 42%) undersized P. armatus and A. australis. In the second experiment, fewer undersized S. serrata, P. armatus, and A. australis were retained in all larger meshed traps, and in all traps with escape gaps. | giant mud crabs (Scylla serrata), blue swimmer crabs (Portunus armatus) | No effect | Field study in the wild | Optimizing mesh size with escape gaps in a dual-species portunid-trap fishery | |
| Skagerrak, Norway | Trawls | Modified ground gear (mobile) | Invertebrates | Bycatch of Norway pout was slightly reduced in the shorter trawl. | Northern shrimp (Pandalus borealis) | The trawls fished shrimp above 19 mm carapace length equally, while catch rates of shrimp below 15.5–16 mm carapace length in the shorter trawl were more than halved. | Field study in the wild | Shorter trawls improve size selection of northern shrimp | |
| The Bahamas | Traps | Invertebrates | Field study in the wild | An assessment of post-release mortality for a commonly discarded deep-sea isopod (Bathynomus giganteus) using reflex impairment | |||||
| Electromagnetic deterrents | Invertebrates | N/A | Shrimp tended to do a tail flip in response to some electric pulses and ragworm showed a squirming response independent of the frequency. | N/A | Study in the lab | Determining the safety range of electrical pulses for two benthic invertebrates: brown shrimp (Crangon crangon L.) and ragworm (Alitta virens S.) | |||
| Spencer Gulf | Trawls | Excluder devices | Invertebrates | Reduced capture of giant cuttlefish and blue swimmer crabs by 30-50% | King prawn | Catch of target species was not affected | Field study in the wild | Mitigating the bycatch of giant cuttlefish Sepia apama and blue swimmer crabs Portunus armatus in an Australian penaeid-trawl fishery | |
| Spencer Gulf | Trawls | Excluder devices | Invertebrates | Small and large grids reduced number and weight of cuttlefish and crabs | Prawn | Small grid caught less prawns compared to large grid and control nets | Field study in the wild | Bycatch reduction devices (BRDs) to reduce the incidental catch of cuttlefish in the Spencer Gulf prawn fishery | |
| North Sea | Trawls | Electromagnetic deterrents | Bony Fishes, Invertebrates | Overall reduction in bycatch of 35% | Shrimp | 50% more shrimp caught | Summary study | Electrotrawling: a promising alternative fishing technique warranting further exploration | |
| North Sea | Trawls | Electromagnetic deterrents | Bony Fishes, Invertebrates | 30-50% reduction in fish and 48-73% reduction in benthic discards | Flatfish | Catches were 65-69% lower compared to conventional trawls | Summary study | Electrotrawling: a promising alternative fishing technique warranting further exploration | |
| Lake Maracaibo, Venezuela | Gillnets | Deep sets, Sub-surface sets (gillnets) | Sharks, Skates/Rays, Bony Fishes, Elasmobranchs, Invertebrates | None, reduced bycach capture rate | shrimp | None | Field study in the wild | Selectivity of three artisanal fishing gears used for the capture of the white shrimp, Litopenaeus schmitti, in the Bay of El Tablazo, Zulia State, Venezuela | |
| Venezuela | Trawls | Modified ground gear (mobile) | Sharks, Skates/Rays, Bony Fishes, Elasmobranchs, Invertebrates | Decrease of 26-32% | shrimp | Maintained or increased | Field study in the wild | The use of devices to reduce bycatch in Venezuelan shrimp fisheries and the FAO Code of Conduct for Responsible Fishing | |
| North Sea | Trawls | Modified ground gear (mobile) | Bony Fishes, Invertebrates | Significantly fewer invertebrates; no difference in undersized plaice; significantly fewer undersized sole | Plaice and sole | Significantly fewer plaice and sole | Field study in the wild | Performance of pulse trawling compared to conventional beam trawling | |
| Isle of Man | Trawls | Modified ground gear (mobile) | Invertebrates | There was no significant difference in the abundance of bycatch between the traditional and new "Newhaven" dredge design. | Queen scallop | The new "Newhaven" dredge caught significantly more queen scallops than the traditional dredge. | Field study in the wild | Efficiency and environmental impacts of three different queen scallop fishing gears | |
| Izmir Bay, Turkey | Gillnets | Sub-surface sets (gillnets) | Invertebrates | Trial 1, experimental net caught 44% fewer crabs and mantis shrimp and 49% fewer murex than control net. Trial 2, experimental net 1 caught 66% fewer crabs, 27% fewer mantis shrimp and 32% fewer murex, while experiemnetal net 2 caught 51% fewer crabs, | Prawns | Trial 1, experimental net 1 caught 17% fewer prawns than the control net. Trial 2, experimental net 2 caught 2% fewer prawns than the control net. | Field study in the wild | Bycatch reduction in trammel net fishery for prawn (Melicertus kerathurus) by using guarding net in Izmir Bay on Aegean Coast of Turkey | |
| Northern Australia | Trawls | Excluder devices | Elasmobranchs, Invertebrates, Sea Turtles | Little effect | Prawns | Little effect | Field study in the wild | The impact of turtle excluder devices and bycatch reduction devices on diverse tropical marine communities in Australia's northern prawn trawl fishery | |
| Northern Australia | Trawls | Excluder devices | Invertebrates | Downward facing TEDs reduced large sponge catches by 95.9% | Prawns | Reduced the proportion of soft and damaged prawns by 63.2% and reduced catches of tiger prawns by 6.3% | Field study in the wild | The impact of turtle excluder devices and bycatch reduction devices on diverse tropical marine communities in Australia's northern prawn trawl fishery | |
| Northern Australia | Trawls | Excluder devices | Invertebrates | Upward facing TED's reduced large sponge catches by 81.6% | Prawns | Reduced the proportion of soft and damaged prawns by 35.8% and reduced catches of tiger prawns by 6.3% | Field study in the wild | The impact of turtle excluder devices and bycatch reduction devices on diverse tropical marine communities in Australia's northern prawn trawl fishery | |
| Northern Australia | Trawls | Excluder devices | Invertebrates | Reduced large sponge catches by 85.3% | Prawns | Reduced the proportion of soft and damaged prawns by 41.6% and reduced catches of tiger prawns by 6.5% | Field study in the wild | The impact of turtle excluder devices and bycatch reduction devices on diverse tropical marine communities in Australia's northern prawn trawl fishery | |
| United Kingdom | Dredge | Excluder devices | Invertebrates | Reduced likelihood of mortality | Scallops | Decreased for deep-dwelling scallops, increased for surface-dwelling species | Field study in the wild | Hydrodredge: Reducing the negative impacts of scallop dredging | |
| North Sea | Trawls | Modified ground gear (mobile), Raised footropes | Invertebrates | Reduced bycatch | shrimp | Negligible effect | Field study in the wild | On electrical fishing for brown shrimp (Crangon crangon) II. Sea trials | |
| North Sea | Trawls | Electromagnetic deterrents | Invertebrates | Reduced bycatch | shrimp | Negligible effect | Field study in the wild | On electrical fishing for brown shrimp (Crangon crangon) II. Sea trials | |
| Australia | Trawls | Excluder devices | Invertebrates | Reduced bycatch | Shrimp and scallop | Did not affect target catch | Field study in the wild | Benefits of square mesh codends in Queenslands scallop and prawn trawl fisheries | |
| Australia | Trawls | Invertebrates | Reduced bycatch | Shrimp and scallop | Reduced catch by about 10% | Field study in the wild | Design and assessment of two gear modifications to reduce the benthic impact and fuel intensity of prawn trawling in Australia | ||
| Australia | Trawls | Invertebrates | Reduced bycatch of starfish but increased bycatch of nektobenthic species | Shrimp and scallop | Decreased shrimp catch, increased scallop catch | Field study in the wild | Design and assessment of two gear modifications to reduce the benthic impact and fuel intensity of prawn trawling in Australia |
