Bottom trawling is when a net is towed just above or on the bottom of the seafloor in New Zealand fishing grounds.
Fishers target popular species such as hoki, orange roughy and snapper near the bottom of the seafloor because that is where these fish are abundant.
By typically returning to the same fishing grounds each season, fishers are able to catch enough fish by bottom trawling less than five per cent of our oceans each year. Fishing grounds are comparable to a farmer’s fields – they are used specifically for food production and limit the effects of this production to a particular area.
Almost one-third of our ocean seafloor is closed to trawling, in closed marine protection areas that typically have high levels of ocean biodiversity.
The comparatively small area of fishing grounds mostly have sandy or muddy seafloors.
By sticking to sandy and muddy seafloors, expensive fishing nets do not get caught on rocks, coral or seaweed. It also helps to minimise disturbance to the seafloor. And because the nets can be towed without snagging, less fuel is required to tow them, reducing trawling’s carbon footprint.
Technology is also increasingly enabling greater sustainability in trawling. Fishers are quick to invest in and adopt new technology and precision fishing technology in voluntary use by commercial fishers is shrinking the trawling footprint further.
Smaller fleets of vessels are catching the same amount of fish on shorter trips. Nets have bigger mesh to let smaller fish out and weigh a lot less, so they run more lightly along the seafloor. And sensors on the nets tell a skipper when a net is full so they can bring it up sooner.
These are just some examples of the ways that bottom trawling can be sustainabe.
From sea to me: A look at how our fish is caught (Stuff)
Getting to the bottom of trawling (Stuff)
Common misunderstandings and misinformation about trawling [PDF]
The Update: When science meets the bottom trawling debate
The Update: Bottom trawling and carbon – the facts at last
Find trawling troubling? Take heart from the data
PSH: Taking successful sustainable fishing technology to the world
Meet some of the people who work to supply the fish we love to eat.