Study

Reduced herding of flounders by floating bridles: application in Gulf of Maine Northern shrimp trawls to reduce bycatch

  • Published source details He P., Rillahan C. & Balzano V. (2015) Reduced herding of flounders by floating bridles: application in Gulf of Maine Northern shrimp trawls to reduce bycatch. ICES Journal of Marine Science, 72, 1514-1524

Actions

This study is summarised as evidence for the following.

Action Category

Modify a bottom trawl to raise parts of the gear off the seabed during fishing

Action Link
Marine Fish Conservation
  1. Modify a bottom trawl to raise parts of the gear off the seabed during fishing

    A replicated, controlled study in 2011 of an area of seabed in the Gulf of Maine, North Atlantic Ocean off Portland, USA (He et al. 2015) found that the effect of modifying a shrimp trawl to raise the connecting wires between the doors and net (bridles) off the seabed on unwanted fish catch varied between species, compared to conventional trawls with bridles in contact with the seabed. Of seven unwanted (non-commercial target) fish species/groups monitored, average catch rates were lower in modified trawls for three: long rough dab Hippoglossoides platessoides (3 kg/h), redfish Sebastes fasciatus (2 kg/h) and all flounders combined Pleuronectoidei (4 kg/h), compared to conventional trawls (plaice: 2, redfish: 1, flounders: 3 kg/hr). Catch rates of silver hake Merluccius bilinearis, Atlantic herring Clupea harengus, red hake Urophycis chuss and witch flounder Glyptocephalus cynoglossus were similar between gears (raised bridles: 2–38 kg/h, conventional: 1–35 kg/h). In addition, catch rates of the commercial target Northern shrimp Pandalus borealis was similar between gears (raised bridles: 141 kg/h, conventional: 146 kg/h). Data were collected on a commercial vessel from 30 trawl deployments/gear type between March–May 2011. For the modified gear (raised bridles), the wire bridles were replaced with polypropylene rope, while the conventional gear had steel wires. Codend mesh size was 43 mm. Tows were between 90–155 m, 2.3 knots and 1 h duration. All catch was identified and counted.

Output references

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