Oregon Department of Fish and Wildlife and Pacific States Marine Fisheries Commision. Part funded by NOAA Fisheries Bycatch Reduction Engineering Program
Robert W. Hannah, Mark J.M. Lomeli, Stephen A. Jones.
Eulachon (threatened smelt), Flatfish, Dark-Blotched Rockfish
A number of bycatch species are affected by shrimp fisheries in the western coasts of the United States and Canada, including Eulachon, Rockfishes and Flatfishes. In particular, the Eulachon – historically used for oil – is threatened in this area, as well as the Dark-Blotched Rockfish, which is commercially and ecological important. Subsequently, rigid-grate bycatch reducing devices (BRDs) are now a requirement on shrimp trawls, as they allow bycatch to swim to an escape exit on nets. However, small Eulachon can still fit through the minimum spacing requirements on BRD grates (19.1mm) and can remain in the net. Therefore, researchers set out to try and tackle this bycatch problem which the rigid-grate BRD fails to address.
BRDs can be implemented on fishing gear to increase catch selectivity. One such device is artificial light, where light can elicit differential behavioural responses in fish by
- a) causing attraction or repulsion to fishing nets and
- b) illuminating escape routes for non-target species on modified fishing gear.
This scientific study used 10 green LED lights (Lindgren-Pitman Electralume®, centered on 540 nm, ≥0.5–2.0 lx) along the trawl fishing line of an ocean shrimp trawler, to determine whether bycatch could be reduced. In total, 42 hauls occured, and fishing was conducted in Newport, Oregon.
The addition of green lights along the fishing line of the trawl reduced bycatch by between 69 and 91%, whilst not affecting the catch of target species. Light could allow fishing vessels to reduce bycatch whilst maintaining target catch.
|Species:||Addition of lights|
|Ocean shrimp (target)||No affect|
|Eulachon (bycatch)||91% reduction|
|Flatfishes (bycatch)||69% reduction|
|Dark-blotched rockfish (bycatch)||82% reduction|
Hannah, R. W., M. J. Lomeli, and S. A. Jones. 2015. Tests of artificial light for bycatch reduction in an ocean shrimp (Pandalus jordani) trawl: strong but opposite effects at the footrope and near the bycatch reduction device. Fisheries Research 170:60–67.