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Bottom Trawlers: How Low Can They Go?

Gareth Hughes



2000m down everything is pitch black; a human would be crushed under the enormous pressure; yet a myriad of weird and undiscovered sea life exists. Scientists estimate there could be 100 million species that are undiscovered in the ocean depths. The deep ocean is truly one of our last wildernesses – yet kiwi fisherman are taking part in one the largest destructions to occur on our planet.
Bottom trawling involves dragging large nets over the ocean floor with the ability to catch enormous concentrations of fish. In New Zealand, fishers target species such as orange roughy and oreo. The ocean floor isn’t flat like most people assume. Rather it has landscape features like the land, and can alternate from rolling hills to steep mountains called ‘pinnacles’ by the fishermen, and these mounts are rich fishing grounds. New Zealand is an ocean super-power and has the forth largest exclusive economic zone (EEZ) in the world, most of it comprising rich, rocky differentiated landscapes covered in lush coral and sponge growth. We have roughly 1000 undersea mountains, and like on land these comprise many diverse ecological niches. Because of the stillness and isolation half of all species are endemic to that mountain.
Sadly all but one of these mountains have been bottom trawled by, on average, 500m wide nets, with large metal rollers and 2–4 tonne ‘trawl-doors’ or ‘spreaders’ are dragged relentlessly up or down, crushing and grabbing all in their path. Sailing on the Rainbow Warrior in pursuit of New Zealand bottom trawlers in International waters I witnessed a large man-sized coral ‘tree’ being dragged up and thrown overboard, and have heard anecdotally from former trawlers that for every 4 tonnes of orange roughy caught, 10 tonnes of coral will be brought up. Dead.
New Zealand’s bottom trawling story starts in 1979 when a Soviet exploratory trawler discovered a previously undiscovered fish that had amazing properties – it was in abundance, caused diarrhoea if not prepared correctly and yet could be freeze-thawed, freeze-thawed, making it a perfect export fish. From then on the gold rush was on, yet the fishermen knew little about the ‘slime-head’ (later to be called the more marketing-friendly, orange roughy), and only in 2003 was the first juvenile discovered. This discovery helped age most commercially-caught fish, at 150 (or more) years old, which is way older than your granny.
New Zealand pioneered much of the technology that is used for bottom trawling, and we are a world leader amongst the eleven nations that do 95% of the bottom trawling in International waters. We are leaders in destruction; seeing orange roughy populations plummet, leading to a recent closure of one third of New Zealand’s EEZ and much of the ocean floor ecosystems destruction, leading to the biological extinction of our native umbrella octopus, who used coral as a base for its eggs.
We are vocal on Japan’s illegal whaling and were passionate opponents of drift net fishing yet we are doing little internationally to stop the destruction we are causing. The United Nations is in the process of defining the future of bottom trawling in International waters and come December, hopefully there will be an International moratorium in place. Before that happens our Government must stand up to aggressive lobbyists (such as Sealords and Talleys) and be on the side of conservation. Recently large tracts of the Indian Ocean were voluntarily put off limits to NZ trawlers, cynically after we had fished to destruction most of it. Embarrassingly we are being trumped by George W. Bush who recently closed off Alaskan waters larger than the size of Texas to bottom trawlers.
We need our Government to support the moratorium on bottom trawling in International waters and you can write the Minister of Fisheries Jim Anderton and Foreign Minister Winston Peters urging them to be world leaders in marine conservation.
FIGURE 1. Independent Activists Meghan Hughes and Russ Pollard hold a banner out side Parliament protesting at the Governments lack of support stopping bottom trawling, in contrast to their policy on whaling.
FIGURE 2. Blobfish – Psychrolutes microporos The blobfish is a scorpaeniform – a group of which contains the most armoured and scaly and spiney spiked fish in the sea. The full range of this deepwater (750-1200m) fish is not yet known, this blobfish was collected at 1200m on the Southern Norfolk Ridge in the Tasman Sea. Scientists can only guess at how the fish feeds and based on its body shape is believed to be an ambush predator that will eat whatever it can fit in. The purpose of the proboscis (nose) is unknown. This fish was discovered on a NORFANZ expedition in 2003. Read original source.
FIGURE 3. NZ bottom trawlers aboard the Auckland vessel Waipori throw overboard a 500 year old Gorgonian coral: unintended bycatch. (Photo Greenpeace 2004)