Fishing gear - the tools of the trade

Bottom trawling

Description: Large, cone-shaped net dragged across the seafloor.
Used to catch: Fish and shrimp.
Bycatch: Everything in the net’s path: Turtles, marine mammals, juvenile fish, non-target fish, invertebrates, corals,

Gillnets

Description: Translucent curtain of net designed to catch fish by their gills or fins; sometimes several kilometres long and 20-30 metres in height. The nets can be anchored to the seafloor, or suspended at or below the surface (driftnets).
Used to catch: Fish, and occasionally shrimp / other crustaceans
Bycatch: Everything larger than the net’s mesh: juvenile fish, non-target fish and sharks, seabirds, crustaceans, marine mammals, marine turtles, invertebrates. Animals scavenging on fish caught in the net can also become entangled, such as seals and sea lions Gillnets that are lost at sea are rarely recovered. These “ghost nets” can continue to capture marine animals for many years.

Longlines

Description: A single strand of fishing line up to 100 kilometres long, set with thousands of baited hooks. Longlines can be set in the water column or on the seafloor.
Used to catch: Fish
Bycatch: Any marine animal large enough to bite the bait and hook: juvenile fish, non-target fish and sharks, marine turtles, seabirds, marine mammals.

Purse seine nets

Description: Large net usually 1.5-2 kilometres in length and 120-250 metres in height set around a school of fish, then pulled closed from beneath like a drawstring purse. Commonly used in tuna fisheries with Fish Aggregation Devices (FADs) – an object that floats in the water which attracts small fish (seeking refuge) which, in turn, attract larger commercially valuable fish species.
Used to catch: Fish
Bycatch: Everything larger than the net’s mesh: sharks, juvenile fish, non-target fish, marine turtles, marine mammals. Bycatch is particularly high when used with FADs.

Dredging

Description: Large metal frame with an attached chain-mesh net or bag dragged along the seafloor, often digging deep into the seabed.
Used to harvest: Scallops and other mollusks and sea urchins
Bycatch: Anything in the net’s path: fish, juvenile fish, invertebrates, aquatic vegetation.