What is bottom trawling?

Bottom trawling is a method of fishing that involves dragging heavy weighted nets across the sea floor, in an effort to catch fish. It’s a favoured method by commercial fishing companies because it can catch large quantities of product in one go.

In New Zealand, commercial fishing companies bottom trawl both within our waters and in international ones. In fact, we are one of only seven countries still using this practise in international waters. 

Bottom trawling by NZ fisheries

What are bottom trawlers fishing for?

New Zealand fishing companies are primarily bottom trawling for orange roughy and oreo.  These are deepwater species, often found around seamounts – submarine mountains. Most of the fish trawled by the New Zealand fleet are then exported to China or the United States. 

Why is bottom trawling destructive?

The problem with bottom trawling as a fishing method is that it’s indiscriminate in what it catches. When dragging the large, weighted nets across the seafloor, everything that happens to be in the way gets swept up in the net too. For this reason bottom trawling has a large bycatch impact, with many non target species being fished in the process. 

This has an impact on the biodiversity of the ocean, and also means many species are being fished to the brink simply as a consequence of commercial activities, not as the target of them. 

In addition to the turtles, juvenile fish and invertebrates that get swept up in trawling nets, deep sea corals are hidden victims of trawling.  

Deep sea coral forests, thought to be some of the most biodiverse ecosystems with high degree of endemism (species found only there), can take centuries to form. But when a trawler runs over them again and again to catch fish, they’re destroyed, and so is the whole community that had formed around them. 

Consider a forest on land. The ancient trees are worth saving alone, but when you bulldoze a forest you also lose the whole ecosystem of smaller plants and animals that have found a home there. We’ve all shed a tear watching the video of a solo orangutan, clinging to the last tree as bulldozers level its forest home. But this is happening in our oceans too.  What happens there is so out of sight, it’s simply out of mind for many.

Black seabream, yellow amberkacks, Mount Vema seamount, Seamount biodiversity, Greenpeace, Greenpeace pole to pole, Bottom trawling on seamounts
Shoals of black seabream and yellowtail amberjacks circle above one of Mount Vema’s summits.
Seamounts are known to be unique ecosystems.

Coral forests, coined the ‘kauri of our ocean,’ act as nurseries for juvenile fish and other invertebrates, and are often found on seamounts. These places are vital not just for the communities of fish, starfish, crabs, sea urchins, brittle stars, mollusks, sponges, and worms that live there, but are also thought to be vital stop off points for migratory species like whales. It’s thought some species of whales even use seamounts for navigation and to stop and feed during their long journeys. 

Trawlers target seamounts because they are known hot spots for fish and other marine life. The key species they are after often hang out on seamounts, so they trawl over them to get their catch.

Paragorgia coral dredged, bottom trawling coral, bottom trawling New Zealand, New Zealand bottom trawling vessel, ancient coral forests
Crewman on the New Zealand bottom trawler, Waipori, dump a large piece of Paragorgia coral dredged from the deep sea in their net.

Does bottom trawling still happen in New Zealand?

A common misconception is that New Zealand has banned bottom trawling. We haven’t. The industry volunteered to ‘protect’ a third of New Zealand waters, but most of the areas they chose were unsuitable for bottom trawling anyway. It was essentially protecting what couldn’t be touched even if they had wanted to. Meanwhile, many seamounts and hotspots for marine life are still trawled to this day – and last year the quota for Orange Roughy was increased, meaning even more trawling. 

When it comes to bottom trawling, New Zealand is one of the bad guys. We’re one of only seven countries that still bottom trawl in the High Seas – in those areas beyond national borders where laws are hazy. 

The UN’s advice (Resolution 61/105 – 64/72 – 66/68)  is that all vulnerable areas, with precious ecosystems, like sea mounts should be closed to bottom trawling. New Zealand signed on to these resolutions, but we are failing to live up to international expectations. 

New Zealand owned fishing companies, such as Sanford and Talley’s, trawl internationally and in New Zealand waters. A whole host of companies trawl within our EEZ.

Amaltal Apollo, Talley's, Talley's vessels, Talley's fisheries, bottom trawling boats, SPRFMO
The Amaltal Apollo, that was caught trawling in a protected area, pictured here in the Port of Nelson. © Jason Blair

On the domestic front, trawling has been blamed for the degradation of some of our coastal waters – and is at least partly to blame for the sorry state of the Hauraki Gulf.

Internationally, we don’t do much better. At the most recent meeting of SPRFMO (South Pacific Regional Fisheries Management Organisation) meeting, New Zealand lobbied for weaker regulations on trawling. Representatives for New Zealand lobbied for more coral bycatch to be allowed per trawl, while other nations tried hard to make the laws stricter to protect the oceans.

At this same meeting, New Zealand delegates lobbied to have a Talley’s owned fishing vessel, the Amaltal Apollo, removed from the fishing blacklist, after it was caught bottom trawling in a protected area. They won this appeal. 

Bottom trawling and the biodiversity crisis

At a time when the world faces an unprecedented biodiversity crisis, methods of fishing that cause damage to such slow growing ecosystems can no longer be afforded. Last year alone, the New Zealand fleet destroyed up to 3,000 tonnes of deep sea corals in their relentless trawling. 

Scientists tell us that we must protect a third of the world’s oceans if we want to save them from collapse, and that means protecting them from devastating activities like this.

If we want to prevent more species from going extinct, or joining the growing IUCN red list we must take decisive action to restrict activities that are known to destroy and disturb vital ecosystems that support life on Earth.

Bottom trawling and climate change

Not only is bottom trawling bad for marine life, it’s also contributing to the climate crisis in a big way. It turns out that dragging heavy nets across seabed disturbs marine sediments, which is the world’s largest carbon sink.

Fishing boats that drag heavy nets through the ocean to trawl the sea floor, often at great depths, release as much carbon dioxide as the entire aviation industry, according to a groundbreaking 2021 study.

The carbon is released from the seabed sediment into the water, and can increase ocean acidification, as well as adversely affecting productivity and biodiversity. Marine sediments are the largest pool of carbon storage in the world.

Reasons for hope 

For decades, Greenpeace has been campaigning hard to protect the oceans. 

Last month, a new study published in Nature revealed that ocean recovery is possible within the next three decades – so long as we start increasing protection now.

It states: “We are at a point at which we can choose between a legacy of a resilient and vibrant ocean or an irreversibly disrupted ocean, for the generations to follow.”

The study puts in no uncertain terms that we have the opportunity to protect our oceans for the future well-being of the planet, but it is going to take co-operation on an international scale.

A strong Global Ocean Treaty has the power to make ocean recovery possible over the next thirty years. Getting this across the line could pave the way for a network of ocean sanctuaries around the world, with the ability to protect unique ecosystems so they can recover.

You can be part of this vital movement by signing the petition here.

Greenpeace New Zealand is also running a campaign with our allies DSCC, WWF, Forest & Bird and ECO, to ban bottom trawling on seamounts – because these ecosystems are so vulnerable and slow growing. It’s our belief that these ancient coral forests should be protected from bottom trawling to enable them to continue supporting a diverse range of marine life.

NZ trawler dumps huge coral bottom trawling
PETITION: Ban bottom trawling on seamounts

Join the call to demand that the NZ Govt bans bottom trawling on seamounts and similar deep sea features, and stop issuing permits for bottom trawling in international waters.

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